ENBQuarterly - MOH

ENB Quarterly | Vol 44 (3) | 69

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EPIDEMIOLOGICAL NEWS BULLETIN JUL 2018Vol. 44 No. 3 SINGAPORE● ● ●

ENBQuarterly

An Influenza Outbreak with Environmental Contamination in a Primary School

See page 78

Concurrent Outbreaks of Respiratory

Pathogens in Three Long-Term

Care Facilities See page 71

PLUSRegional Experience in Field Epidemiology Training: A Comparative Analysis of the Singapore, US, UK and European Models See page 84

70 | ENB Quarterly | Vol 44 (3)

ARTICLES

Working with Warriors in Malaria Control

90

NEWSDESK

Concurrent Outbreaks of Respiratory Pathogens in Three Long-Term Care Facilities

71

MOH Budget 2018 Initiatives

98

Regional Experience in Field Epidemiology Training: A Comparative Analysis of the Singapore, US, UK and European Models

78

The focus for our July issue is on droplet-borne and contact transmissible diseases. Herein, we document two interesting institutional outbreaks.

The first article describes a spatiotemporal cluster of respiratory illness in three long term care facilities located within the same compound. This outbreak highlights the importance of early detection through surveillance, up-to-date influenza vaccination, and a multipronged infection control approach involving clear communication and collaboration between stakeholders to curb transmission.

Our second article is an investigation into an influenza A outbreak showing widespread contamination of fomites in a primary school. While influenza activity increases during winter in temperate countries, Singapore experiences outbreaks all year round due to our unique location at the crossroads of both hemispheres. Because children congregate in schools, they need to maintain high standards of hygiene and cleanliness for effective control.

We also have a special article on the Singapore field epidemiology training programme featuring a comparative analysis that benchmarks us against established programmes in the US, UK, and European Union. While the course duration, curriculum modules, and criteria for completion remain similar, all four models have each tailored training according to their specific country and regional needs.

Further, in Notes from the Field, we have a sharing by our colleagues who attended NEA’s field training in malaria control. This programme provides experience on Anopheles mosquito surveys and trappings at night for assessing effectiveness of vector control.

Editor’s note

CONTENTS

104 Infectious Diseases Update

Lead Article

Scientific Contributions

Notes From the Field

Fast Facts

Surveillance SummarySteven

An Influenza A Outbreak with Environmental Contamination in a Primary School

84


LEAD ARTICLE

Concurrent Outbreaks of Respiratory Pathogens in Three Long-Term Care Facilities

INTRODUCTION

Outbreaks of respiratory pathogens are common in long-term care facilities (LTCFs) as the elements for transmission of infections such as infectious agents, susceptible residents and conducive environment for easy spread are all present.1,2 Such outbreaks often lead to a substantial morbidity and mortality and are also disruptive and costly. Influenza and rhinovirus/ enterovirus are common respiratory viruses and they spread from one person to another through respiratory droplets during coughing, sneezing or speaking, or via contaminated surfaces. Outbreaks of influenza and/ or rhinovirus/enterovirus are common among residents of LTCFs.3,4 Surveillance of infectious diseases in LTCFs, infection prevention and control programmes and established outbreak response measures are the key factors for the prevention and control of infectious diseases outbreaks, including respiratory outbreaks in LTCFs.5

In Singapore, LTCFs as well as other healthcare institutions report outbreaks of infectious diseases to the Ministry of Health (MOH). In 2016, a total of 43 outbreaks of healthcare-associated infections were reported and respiratory illnesses caused most of the cases.6 The common respiratory pathogens identified in LTCFs’ outbreaks included influenza viruses, rhinovirus/enterovirus, human parainfluenza virus, Streptococcus pneumoniae, and Mycoplasma pneumoniae.7 We report herein the investigations in May 2017 into concurrent respiratory outbreaks caused by influenza A and rhinovirus/enterovirus

among residents and staff of three LTCFs located within the same complex in Singapore.

METHODS

On 17 May 2017, MOH was alerted by LTCF A of cases with fever and/ or respiratory symptoms among its residents. While the information was being verified with LTCF A, two days later on 19 May 2017, a public acute hospital within the regional healthcare cluster informed MOH that nine residents from LTCF B were admitted to their hospital and they tested positive for influenza A. It was also brought to the MOH’s attention that non-emergency febrile cases from LTCF B were sent to the Emergency Department of the hospital for treatment via SCDF 995 ambulances (emergency ambulance).

Both LTCF A and B house male residents only and are located in the same compound. The complex comprises of LTCFs managed by various organisations and an activity centre. Please see Figure 1 for the layout of the complex.

Epidemiological investigations were immediately conducted by the Healthcare Epidemiology (HCE) team of MOH to determine the extent of the outbreak, source of infection, the causal pathogen and the mode of transmission, and to assist the LTCFs in preventing spread of infection and controlling the outbreak.

Kelly Foo1, Khine Nandar1, Constance Low1, Imran Roshan Muhammad1, Mak Tze Minn2, Cui Lin2, Steven Peng-Lim Ooi1

1Communicable Diseases Division, Ministry of Health, 2National Pubic Health Laboratory, Ministry of Health


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A case was defined as any resident or staff of LTCFs and the activity centre who developed two or more of the respiratory symptoms (i.e. fever, cough, runny nose, sore throat, breathlessness) on or after 29 April 2017 (eight days prior first case’s onset date). Individuals who received influenza vaccination within one year prior to onset of illness were regarded as vaccinated against influenza.

Epidemiological investigations involved the daily collection of cases’ details from the affected LTCFs (personal particulars, age, gender, symptoms, influenza vaccination status, treatment mode), the review of the activities at the activity centre and residents attendance of these activities, and an onsite field investigation on 22 May 2017.

During the visit, the MOH officers met with the management and nursing teams of LCTFs A and B and reviewed their work processes, including surveillance for infectious diseases, the standard operation procedures (SOPs) for the management of residents with infectious diseases symptoms, outbreak management, infection prevention and control measures, and environmental cleaning practices. We also conducted door-to-door visits to the remaining four LTCFs and the activity centre in the campus to find out if they detected any respiratory cases/cluster recently. They were also alerted to report to MOH if there were such cases.

On 24 May 2017, two days after the visit, LTCF C reported the third respiratory cluster affecting 13 residents since 21 May 2017. In addition, the activity centre retrospectively reported four respiratory illness cases among their staff with illness onset between 8 and 19 May.

Nasopharyngeal swabs were obtained from the cases and tested for respiratory pathogens via respiratory multiplex polymerase chain reaction (PCR) FilmArray test (pathogens tested under FilmArray include adenovirus, coronavirus HKU1, coronavirus NL63, coronavirus 229E, coronavirus OC43, human metapneumovirus, human rhinovirus/enterovirus, influenza A, influenza A/H1, influenza A/H3, influenza A/H1-2009, influenza B, parainfluenza virus 1, parainfluenza 2, parainfluenza 3, parainfluenza 4, respiratory syncytial virus, Bordetella pertussis, Chlamydophila pneumoniae, Mycoplasma pneumoniae). Further analysis was conducted on the positive influenza A isolates via whole genome sequencing (WGS) at the National Public Health Laboratory (NPHL). RESULTS

A total of 138 cases (128 residents and 10 staff) of respiratory illness with onset dates from 7 to 26 May 2017 were reported from three LTCFs and the activity centre (Table 1 and Figure 2). The highest number of cases and the highest attack rate were observed at LTCF B where 74 cases were affected with 34.6%

Figure 1. Layout of the complex illustrating three affected LTCFs and the activity centre


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Table 1. Characteristics of cases in three affected LTCFs during the influenza A and Human Rhinovirus/ Enterovirus outbreaks in May 2017

Characteristics LTCF A (n=38)

LTCF B (n=74)

LTCF C (n=22)

Activity Centre (n=4)

Total (N=138)

%

Age group (in years) [n=134]

20 – 29 30 -39 40 - 49

1 1 4

1 3 3

0 1 3

2 5

10

1.49 3.73 7.46

50 - 59 11 20 9 40 29.85 60 - 69 13 26 7 46 34.33 70 - 79 6 17 2 25 18.66 80 - 89 2 4 0 6 4.48 Sex [n=134] Female 0 0 2 2 1.49 Male 38 74 20 132 98.51 Ethnic group [n=134]

Chinese Malay Indian

23 4 8

39 20 10

9 6 7

71 30 25

53 22 19

Others 3 5 0 8 6 Cases Resident 36 70 22 0 128 93 Staff 2 4 0 4 10 7 Fever No 10 3 19 3 35 25.36 Yes 28 71 3 1 103 74.64 Cough No 6 44 9 3 62 44.93 Yes 32 30 13 1 76 55.07 Runny nose No 15 44 5 1 65 47.10 Yes 23 30 17 3 73 52.90 Sore throat No 18 64 14 2 98 71.01 Yes 20 10 8 2 40 28.99 Body ache No 15 73 21 4 113 81.88 Yes 23 1 1 0 25 18.12 Cases attended Activity Centre activities between 8-19 May 2017 [n=128]

No Yes

0 38

12 62

4 18

4 0

20 118

81.25 23.44

Cases received influenza vaccine (2016/ 2017)

No Yes

0 38

12 62

4 18

4 0

20 118

14.49 85.51

Laboratory investigation [n=34]

Influenza A Human Rhinovirus/Enterovirus Parainfluenza Virus 3 No pathogen detected

10 0 0 1

13 0 0 0

1 6 1 2

24 6 1 3

70.59 19.35

3.23 10.00


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Figure 3. Epidemic curve of the respiratory illness outbreaks in the LTCFs and the activity centre in May 2017, by laboratory tests results

Figure 2. Epidemic curve of the respiratory illness outbreaks in the LTCFs and the activity centre in May 2017


LEAD ARTICLE

and enhanced their infection prevention and control measures, including frequent hand washing for both residents and staff, use of appropriate PPE (surgical mask) for both residents and staff, and stepped up environmental cleaning.

MOH’s field visit to LTCF A, LTCF B and the activity centre on 22 May identified areas for improvement in environmental cleaning and infection, prevention and control measures. It was found that febrile, yet stable residents were sent to a regional hospital’s Emergency Department for treatment after office-hours via SCDF emergency ambulances. Apart from the above observations, general levels of environmental hygiene and sanitation in the affected LTCFs and the activity centre were found to be satisfactory.

The MOH team suggested improvements in some areas, viz. (i) the stepped up infection prevention and control measures such as hand hygiene, droplet precautions, and environmental cleaning, (ii) visitors screening, (iii) the management of affected and well residents such as cohort nursing, cessation of group activities, and (iv) the annual influenza vaccination for both residents and staff, including the activity centre. Service providers of LTCFs were reminded of the appropriate use of ambulance services, i.e. to activate non-emergency ambulances for cases with fever only (other vital signs stable). They were also advised to

attack rate, while LTCF A and LTCF C reported 38 cases with 22.1% attack rate and 22 cases with 9.9% attack rate, respectively. The highest proportion of cases was observed among residents aged 60-69 years (34.3%), followed by those between 50-59 years old (29.9%). Among the three major ethnic groups, Chinese residents (53%) had the highest number of cases. The most common clinical presentation amongst the cases were fever (74.6%), cough (55.1%) and runny nose (52.9%). Of the 138 cases, 10 cases were hospitalised and later discharged well. The remaining cases sought outpatient treatment.

The overall influenza vaccination coverage amongst the resident-cases in the affected LTCFs ranged from 70% to 96%, and that of the staff-cases ranged from 0% to 92%. The last influenza vaccination was conducted in LTCF A in April 2016, in LTCF B in January 2017 and in LTCF C in December 2016. Based on the information provided by the LTCFs, the influenza vaccines used in LTCF B and LTCF C were the 2016-2017 Northern Hemisphere vaccine. No influenza vaccination exercise was conducted for staff of the activity centre.

A total of 34 specimens were collected for multiplex respiratory PCR testing, of which 24 (70.6%) tested positive for influenza A [influenza A(H1N1)pdm2009 (20), influenza A(H3) (1), influenza A (1), influenza A subtype undetermined (2)]; seven (20.6%) tested positive for Human Rhinovirus/ Enterovirus, and one of these seven specimens also tested positive for adenovirus and parainfluenza virus 3. The remaining three (8.8%) specimens tested negative for respiratory pathogens. The 24 influenza positive specimens were from LTCF A (10), LTCF B (13) and LTCF C (1), while the seven rhinovirus/ enterovirus samples were from LTCF C. Of the 24 influenza positive cases, eight (33.3%) attended programmes at the activity centre prior to or during their respiratory illnesses. The epicurve of the respiratory illness outbreak in these institutions based on laboratory results is shown in Figure 3.

Whole genome phylogenetic analysis on all positive influenza A(H1N1)pdm09 and influenza A subtype undetermined samples from this outbreak showed that the viruses shared high sequence identity and contained a V272I mutation in hemagglutinin (HA) and a V34I reversion mutation in neuraminidase (NA). The phylogenetic tree is shown in Figure 4. The outbreak virus strains were found to be closely related to A/Michigan/45/2015, which was the recommended vaccine strain in the 2017 Southern Hemisphere influenza vaccine.

In response to the outbreak, the affected LTCFs stepped up temperature and health checks of well and affected residents, cohort-nursed affected residents,

Figure 4. Whole genome phylogentic tree of positive influenza A isolates


arrange for after-office hours medical consultations for residents’ health conditions which were of non-urgent and non-serious nature.

The last cases with respiratory symptoms were reported on 26 May after a total of 19 days of transmission. Monitoring of this incident by MOH was ceased on 3 June 2017 after two incubation periods for influenza (eight days) were lapsed without any new case.

DISCUSSION

Our investigations reported concurrent outbreaks of two respiratory pathogens in the complex in May 2017 – influenza A affecting LTCF A and LTCF B, and rhinovirus/enterovirus affecting LTCF C. Nevertheless, the interventions, i.e. infection control measures8,9 to stop these two diseases transmissions were the same and the outbreaks were eventually controlled with the termination of transmission through multipronged infection control approach.

Influenza activity in Singapore is present year round with usually two peak periods around the end or beginning and middle of the year, coinciding with the northern hemisphere (NH) and the southern hemisphere (SH) influenza seasons10 , while rhinovirus/enterovirus are the common respiratory pathogens with local circulation throughout the year.11 These concurrent influenza A and rhinovirus/enterovirus outbreaks in May 2017 coincided with the mid-year increased influenza activity locally.

According to the WGS of positive influenza isolates including influenza A(H1N1)pdm2009 and influenza A subtype undetermined, the viruses among cases of LTCFs A and B were very similar, which suggested a single introduction of the virus to the complex and the subsequent spread across LTCFs, rather than multiple independent introductions from the community to the LTCFs. While the affected LTCFs are operated by different VWOs with minimum communications, their residents interact and mingle during programmes at the activity centre. The team noted during our field visit that the LTCFs were unaware of outbreaks that were happening in the other institutions until MOH’s field visit on 22 May. This might have led to the continuation of mixing of residents from different LTCFs at the activity centre and coupled this with the possibly of symtomatic residents joining the activity centre and the suboptimal level of environmental cleaning there, would have facilitated the spread of the virus amongst residents attending the activity centre and then from one LTCF to another.

WGS phylogenetic analysis of positive influenza A isolates showed that the virus from one resident from LTCF A shared high sequence identity with those from LTCF A as well as LTCF B. Taken together with

epidemiological findings from the review of cases’ attendance at the activity centre and the epidemic curve, this suggested that the source of infection for LTCF B was from a resident-case of LTCF A that attended the workshops at the activity centre. While there were staff from the activity centre who fell ill with respiratory illness between 7 and 19 May, their role in the transmission of viruses in the outbreaks could not be determined as samples were not available for testing at the time of investigations. The sources of infections for LTCF A and LTCF C remained unknown.

Both WGS performed at NPHL and haemagglutination inhibition testing performed by the WHO Collaborating Center for Reference and Research on Influenza in Melbourne for the positive influenza samples showed that the outbreak strains of A(H1N1)pdm2009 were closely related to the recommended 2017 SH vaccine strain A/Michigan/45/2015. Based on the influenza vaccination history reported by the affected LTCFs, the outbreak was unlikely due to vaccine failure but rather outdated vaccination. There was a change in WHO’s recommendations for influenza A(H1N1)pdm09 vaccine strain in the 2017 SH seasonal influenza vaccine composition - from A/California/7/2009 in the 2016-2017 NH vaccine to A/Michigan/45/2015 in the 2017 SH vaccine. MOH recommended the vaccination with the 2017 SH seasonal influenza vaccine for persons who were never vaccinated before or vaccinated more than a year ago, as well as those who previously received the 2016-2017 NH seasonal influenza vaccine or earlier vaccine less than a year ago. LTCFs in this complex were in the midst of preparation to vaccinate their residents and staff when the outbreak struck them.

LTCF A when reporting to MOH of the respiratory cluster took some time to provide detailed epidemiological information on affected residents while the outbreak at LTCF B was alerted to the ministry by a regional hospital. Surveillance is essential for monitoring of illnesses in the LTCFs, to help understand the LTCF’s baseline infections, identify any deviations from the baseline and take immediate actions to prevent or stop the disease transmission and outbreak.

In view of these respiratory outbreaks, MOH together with the LTCF’s licensing authority worked to: (a) improve their protocol for the management of non-emergency cases after-office-hours, so that the use of emergency medical services for non-emergency conditions (transfer of residents with fever but in stable condition to the ED) could be avoided, and (b) enhance influenza vaccine uptake among residents and staff of LTCFs including those from the activity centre.

This outbreak highlighted the importance of early detection through surveillance, keeping up-to-date influenza vaccination for both staff and residents of LTCFs, and multipronged infection control approach, as well as communication and collaboration amongst

LEAD ARTICLE


LTCFs, the regional hospital, the licensing authority of LTCFs and MOH to stopping the transmission of the diseases and managing the outbreaks.

REFERENCES

1. Matheï C, Niclaes L, Suetens C et al. Infections in residents of nursing homes. Infect Dis Clin North Am. 2007;21:761-72, ix.

2. Utsumi M, Makimoto K, Quroshi N et al. Types of infectious outbreaks and their impact in elderly care facilities: a review of the literature. Age Ageing 2010;39:299-305.

3. Strausbaugh LJ, Sukumar SR, Joseph CL. Infectious disease outbreaks in nursing homes: an unappreciated hazard for frail elderly persons. Clin Infect Dis 2003;36:870-6.

4. Asner S, Peci A, Marchand-Austin A et al. Respiratory viral infections in institutions from late stage of the first and second waves of pandemic influenza A (H1N1) 2009, Ontario, Canada. Influenza Other Respir Viruses 2012;6:e11-5.

5. Smith PW, Bennett G, Bradley S et al. Society for Healthcare Epidemiology of America (SHEA); Association for Professionals in Infection Control and Epidemiology (APIC). SHEA/APIC Guideline: Infection prevention and control in the long-term care facility. Am J Infect Control 2008;36:504-35.

6. Ministry of Health, Singapore. Communicable Diseases Surveillance, Singapore 2016. Available at https://www.moh.gov.sg/content/dam/moh_web/Publications/Reports/2017/Full%20Version.pdf (accessed on 17 May 2018)

7. Unpublished data of the Communicable Diseases Division, Ministry of Health Singapore.

8. Communicable Diseases Center (CDC), United States. Interim guidance for influenza outbreak management in long-term care facilities (2 Feb 2017). Available at https://www.cdc.gov/flu/pdf/professionals/interim-guidance-outbreak-management.pdf (accessed on 10 January 2018)

9. Communicable Diseases Center (CDC), United States. Common colds: Protect yourself and others (12 February 2018). Available at https://www.cdc.gov/features/rhinoviruses/index.html (accessed on 10 January 2018)

10. Ang LW, C Lin, Lin R TP et al. Virological surveillance of influenza-like illness in the community, 2011-2016. Singapore Epidemiol News Bull 2017; 43:39-46.

11. Lau YF, Koh WV, Kan C et al. Epidemiologic analysis of respiratory viral infections among Singapore military servicemen in 2016. BMC Infect Dis 2018;18:123.

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SCIENTIFIC CONTRIBUTIONS

An Influenza A Outbreak with Environmental Contamination in a Primary School

INTRODUCTION

Droplet transmission of influenza viruses is well-established1, while contact and airborne transmissions have been suggested as potentially significant modes of spread of influenza in recent years.2-5 Studies as early as 1982 had found the possible role of fomites in the transmission of influenza viruses6 and subsequent studies showed that inactivation of influenza viruses on hands was a factor limiting transmission via this route7,8 and droplet contamination of fomites was more important in transmission than hand contamination of fomites.9 Generally, in community settings, the survival of influenza viruses on environmental surfaces was usually less than one hour.10 However, a 2017 study found that viable influenza A(H1N1)pdm09 could be found on stainless steel, cotton and microfiber surfaces for up to two weeks under laboratory settings.11 Traces of influenza viruses could also be detected by PCR on these surfaces for up to seven weeks, but viability could not be assessed.11

While there have been studies showing that fomite transmission of influenza virus is possible, there has been little documentation of the potential role of environmental and fomite contamination in outbreak settings. This paper details the epidemiological investigation of an outbreak of influenza A in a primary school in Singapore, and the possible roles of different routes of transmission in the propagation of this outbreak. METHODS

On 10 April 2017, the Ministry of Health (MOH), Singapore was informed of 62 individuals (58 students and 4 staff/teachers) from a primary school

in north-western Singapore who had fever, some with accompanying symptoms of cough, sore throat, diarrhoea and abdominal pain.

This primary school is a single-session school with a student and staff population of 1,450. The overall baseline absenteeism rate is about 12 students per day.

As there was a large number of unwell cases, MOH initiated an investigation, which included a site visit on 12 April 2017, to characterise the disease spread, and determine possible sources and/or transmission modes. The aim was to gain clarity on the outbreak and how it spread, and to implement control measures.

A case was defined as a previously well individual from the primary school, who acutely developed fever between 4 and 20 April 2017, or who had tested positive for a likely pathogen that caused the outbreak, based on throat swabs collected during the same period of time. The start of the date range was determined by taking one day before the presumed first case of the outbreak (to look for additional undetected cases), and the end of the date range was determined by the last detected case of the outbreak.

The primary school provided a list of the cases, including basic information on demographics, symptoms, their school class, and date of medical certification (MC) issued by a doctor (which is a requirement for school absenteeism in Singapore). However, the school did not record the date of onset of symptoms of the cases. To allow for imputation, we conducted phone interviews with seven available cases to collect data on the interval between onset of symptoms and the date of their MC.

Andrea Lim, Cherie See, Tze-Minn Mak, Pei Pei Chan, Marc Ho, Steven Peng-Lim Ooi, Vernon Lee

Public Health Group, Ministry of Health



During the field visit, pharyngeal swabs were taken from 10 individuals (eight students from Primary 6 and two staff) by MOH’s Public Health Officers. They had symptoms of fever, sore throat and runny nose three to six days before, but were recovering and had been deemed fit to return to school/work at the time of the collection of the swabs. The swabs were placed in 3ml of universal transport medium (UTM) (Copan Diagnostics) and transported to the National Public Health Laboratory (NPHL) for testing within one hour of the samples being taken.

Environmental samples were also taken from various sites in the school. For each area that was swabbed, the particular surface was swabbed four to five times. The surfaces from which environmental samples to be taken were chosen based on their proximity to the class with the most number of cases (classroom 6C). Samples were taken from inside classroom 6C, as well as the toilet and water cooler outside the classroom. Samples were also taken from the sick bay of the school where sick students awaited to be picked up by their parents.

To determine the causative agent, each sample was tested by FilmArray Respiratory Panel v1.7 (bioMérieux). Whole genome amplification of influenza was achieved based on a protocol adapted from Watson et al (2013)12 and sequencing library was prepared using Nextera XT DNA library preparation kit (Illumina). The products were sequenced on an Illumina MiSeq instrument with MiSeq Reagent Kit V3 (Illumina) and reads were processed using MiSeq reporter by reference mapping to current vaccine strain A/Hong Kong/4801/2014. Phylogenetic trees were drawn using Molecular Evolutionary Genetics Analysis Version 6.013 for all eight segments to determine the phylogeny of viruses sequenced.

RESULTS

There were 81 cases (72 students and 9 staff) in this outbreak. The attack rate was 5.6% (using the entire school population as the denominator). Out of the 81 cases, 50 were male (61.7%). All the students were in the Primary 6 level, apart from two students in Primary 2 and two students in Primary 3 who were the siblings of affected Primary 6 students. Most of the affected staff members did not teach Primary 6 classes and did not report having extensive contact with Primary 6 students. The class with the most number of cases was 6C. The attack rate by Primary 6 class is shown in Table 1.

The primary school had recorded cases based on their date of MC rather than onset of symptoms. As MC was not required for school on the weekends, there

were no cases recorded on the weekends during the outbreak period, 8 to 9 April 2017 and 14 to 16 April 2017 (long weekend due to a public holiday).

Figure 1 shows the epidemic curve based on the date of reporting of illness (the date of MC), and Figure 2 shows the epidemic curve based on the presumed date of illness of the cases, which was derived by imputation. Both charts representing the dates of reporting of illness as well as onset of illness were consistent with a propagated outbreak.

The reported symptoms of the cases were fever (96%), cough (21%) and sore throat (17%). Some cases also reported having diarrhoea (3.7%) and vomiting (2.5%). All the cases sought outpatient treatment, and none were hospitalised.

The site visit on 11 April 2017 found that the students at the primary school were split into educational levels from Primary 1 (7 years old) to Primary 6 (12 years old). They had daily morning assembly where the whole school gathered. In each educational level, students were split into different classes of around 30 to 40 students each, and they remained in these classes for majority of the day, with teachers moving between classrooms to deliver lessons. In certain subjects, such as language classes, the students would be re-grouped into different classes based on the language they were learning. Students also had recess times, about half an hour to visit the canteen for morning tea.

The Primary 6 students (the predominant affected group) were in 10 classrooms located across two blocks. There was some mixing between the students during language lessons. The classrooms were naturally ventilated by fans, with chairs and desks for students. The students sat in pairs with two desks joined together. The pairs of desks were about 0.5 to 1 metres apart from the next pair.

On interviewing the cleaning staff regarding cleaning procedures, it was found that the cleaning staff

Class No. of cases Total no. students Attack rate 6A 9 40 22.5% 6B 6 39 15.4% 6C 20 40 50% 6D 8 39 20.5% 6E 6 27 22.2% 6F 7 34 20.6% 6G 3 23 13.0% 6H 9 35 25.7% Total Primary 6 68 277 24.5%

Table 1. Attack rate of the outbreak by Primary 6 class



mopped up vomitus of students who vomited in class with solution containing bleach. Thereafter, the mop was left in the corner of the janitor’s room to dry.

The school instituted measures to control the outbreak, which included segregating recess break times so that the Primary 6 students did not mix with other levels, informing parents of the outbreak and advising them not to send their child/children to school if they were unwell. Assembly and other mass gathering activities was also ceased during the outbreak period.

Seven out of the 10 pharyngeal swabs were tested positive for influenza A (four for influenza A(H3N2),

three for undifferentiated influenza A); all positive samples were from Primary 6 students. One swab taken from a student was tested positive for rhinovirus. Of the two swabs taken from staff members (teachers), one was positive for Mycoplasma pneumoniae, and the other was negative.

Eight out of the 11 environmental samples were tested positive for undifferentiated influenza A (details shown in Table 2).

The next-generation sequencing performed on the pharyngeal swabs revealed that the four influenza A(H3N2) viruses were genetically similar to the

0

5

10

15

20

25

30

Numb

er of ca

ses

Date of onset

Figure 2. Epidemic curve of respiratory illness among staff and students at a primary school, 4-19 April 2017 (by presumed onset date of illness) (N=81)

0

5

10

15

20

25

30

Numb

er of

cases

Reporting date

6A 6B 6C 6D 6E 6F 6G 6H Staff Other levels

Figure 1. Epidemic curve of respiratory illness among staff and students at a primary school, 5-20 April 2017 (by date of MC) (N=81)



circulating strains in the community, falling within the phylogenetic sub-clade 3C.2a1. Further genetic analysis of the undifferentiated influenza A pharyngeal and environmental swabs was not possible due to the low virus titre. We also attempted to culture all the pharyngeal swab samples but not the environmental samples as the environmental samples were of too low viral titre. However, the influenza virus from the pharyngeal swabs was non-viable.

With improvements to the hygiene and cleaning standards, the outbreak was closed on 28 April 2017 (two incubation periods after the last case on 20 April, taking an incubation period of 4 days for influenza A). At this time, the overall absenteeism rate at the primary school had returned to the baseline of under 12 cases per day.

DISCUSSION

Unlike temperate countries where influenza activity peaks during winter, influenza viruses in Singapore tend to circulate year-round. Influenza B, influenza A(H3N2) and influenza A(H1N1)pdm09 all circulate in the community, causing occasional outbreaks throughout the year. A typical bimodal increase in incidence is usually observed from April to July and from November to January, which coincides with the southern and northern hemisphere winter seasons, respectively. Influenza A outbreaks are not uncommon in Singapore, and are easily propagated in schools as shown in the literature.14,15

Outbreaks in schools generally resolved after enhancing personal hygiene amongst students and curbing of group activities.15,16 A case report in a primary school in Vietnam found that the highest attack rate occurred in the school level with the initial cases, and school class was a strong determinant of

onward virus transmission – which is consistent with the outbreak described in this paper.15

In terms of contaminated environmental surfaces, a study in the United States (US) found influenza A virus on up to 50% of primary school classroom surfaces during influenza A season17 – the most common were high-touch surfaces such as sink faucet handles (57% of samples), paper towel dispenser levers (50%) and student desktops (18.5%).17 There were similar findings from a study in households and day care centers.18 There have been few reports of large clusters of influenza linked to positive environmental samples. our report showed that transmission via fomites could have played a role in transmission and propagation of the outbreak, given the large proportion of commonly contacted environmental samples which tested positive for influenza A, and the rapid transmission of influenza across all Primary 6 classes. However, it cannot be conclusively determined what the main mode of transmission of the outbreak was. There was almost certainly droplet transmission occurring within the classes given the close interaction between the students in the classes.

Given the high potential for spread of viruses in schools, adequate cleaning of the environment would be critical for an outbreak control. We recommended the school to use seperate mops or mop pails to clean vomitus; the used mops should be properly disinfected in a proper designated basin and dried in a proper drying area. It has been previously documented that mops, when stored wet, supported bacterial growth to very high levels and could not be adequately decontaminated by chemical disinfection.19 The MOH’s infection control guidelines for schools was also provided to the school. The surfaces where influenza A were found to be positive were high-touch areas, and the school was advised to concentrate on these areas during routine cleaning, particularly during an outbreak.

The school initiated control measures once the outbreak was detected, including stopping activities where students across levels would mix. This was likely effective in isolating the outbreak to Primary 6 students. This strategy was sufficient as opposed to sending all Primary 6 students home or even closing the school, which had been described to be effective in other outbreaks of influenza A.15,20 Strategies such as closing the school or having all Primary 6 students sent home would have compromised the education of the students, and also had an impact on parents’ plans for care of their children. On the other hand, segregating students by class would pose an undue burden for a school, and also likely to be ineffective given the early spread across the Primary 6 classes. Even when preparing for segregation of students by level,

Sample Result (for influenza A) 6C rear door handle Positive 6C front door handle Negative 6C metal storage cabinet 1 Positive 6C metal storage cabinet 2 Positive 6C light switches 1 Positive 6C light switches 2 Negative Door to toilet (next to classroom 6C) Positive Tap from toilet (next to classroom 6C) Positive Water cooler tap (outside classroom 6C) Positive Sick bay sofa (armrest) Negative Sick bay cushion (on the sofa) Positive

Table 2. Results of environmental samples taken from the primary school



considerations such as having to re-assign teachers and segregating the use of common facilities have to be considered. Therefore, it is important to implement control strategies that are required proportional to the nature of the outbreak, without creating excessive disruption.

One limitation of this investigation was that we could not construct a true epidemic curve based on the date of illness onset, since we only had the date of medical certification (reporting date). As a result, two different charts were presented – one by reporting date and one by date of onset of symptoms by imputation. Both charts showed a propagated outbreak consistent with a typical influenza outbreak. During the field investigation, environmental samples were mostly taken from high-touch areas. Future studies could collect samples in other less commonly contacted areas for comparison. Another limitation was that the influenza virus obtained from the samples was non-viable. This could be due to the samples taken four to five days after the peak of outbreak and in cases who were recovering. As a result, the finding that the virus was non-viable on the throat swab may not be reflective of infectivity during the peak transmission.

CONCLUSION

This outbreak shows the potential for fomite transmission of influenza A, and that hygiene and cleaning standards need to be strengthened to control outbreaks. Strategies need to be put in place for schools and other organisations to manage and contain outbreaks early.

REFERENCES

1. B Brankston G, Gitterman L, Hirji Z et al. Transmission of influenza A in human beings. Lancet Infect Dis 2007;7:257-65.

2. Tellier R. Aerosol transmission of influenza A virus: a review of new studies. J R Soc Interface 2009;6:783-S790.

3. Cowling BJ, Ip DK, Fang VJ et al. Aerosol transmission is an important mode of influenza A virus spread. Nat Commun 2013;4:1935-40.

4. Killingley B, Nguyen-Van-Tam J. Routes of influenza transmission. Influenza Other Respir Viruses 2013;7:42-51.

5. Lindsley WG, Blachere FM, Beezhold DH et al. Viable influenza A virus in airborne particles expelled during coughs versus exhalations. Influenza Other Respir Viruses 2016;10:404-13.

6. Bean B, Moore BM, Sterner B et al. Survival of influenza viruses on environmental surfaces. J Infect Dis 1982;146:47-51.

7. Weber TP, Stilianakis NI. Inactivation of influenza A viruses in the environment and modes of transmission: a critical review. J Infect 2008;57:361-73.

8. Thomas Y, Boquete-Suter P, Koch D et al. Survival of influenza virus on human fingers. Clin Microbiol Infect 2013;20:58-O64.

9. Zhao J, Eisenberg JE, Spicknall IH et al. Model analysis of fomite mediated influenza transmission. PLoS One 2012;7:51984.

10. Mukherjee DV, Cohen B, Bovino ME et al. Survival of influenza virus on hands and fomites in community and laboratory settings. Am J Infect Control 2012;40:590-4.

11. Thompson KA, Bennett AM. Persistence of influenza on surfaces. J Hosp Infect 2017;95:194-9.

12. Watson SJ, Welkers MR, Depledge DP et al. Viral population analysis and minority-variant detection using short read next-generation sequencing. Philos Thrans R Soc Lond B Biol Sci 2013;368:20120205.

13. Tamura K, Stecher G, Peterson D et al. MEGA6: molecular vvolutionary genetics analysis version 6.0. Mol Biol Evol 2013;30:2725-9.

14. Mimura S, Kamigaki T, Takahashi Y et al. Role of preschool and primary school children in epidemics of influenza A in a local community in Japan during two consecutive seasons with A(H3N2) as a predominant subtype. PLoS One 2015;10:0125642.

15. Duong TN, Tho NT, Hien NT et al. An outbreak of influenza A(H1N1)pdm09 virus in a primary school in Vietnam. BMC Res Notes 2015;8:572.

16. Gurav YK, Pawar SD, Chadha MS et al. Pandemic influenza A(H1N1) 2009 outbreak in a residential school at Panchgani, Maharashtra, India. Indian J Med Res 2010;132:67-71.




17. Bright KR, Boone SA, Gerba CP. Occurrence off bacteria and viruses on elementary classroom surfaces and the potential role of classroom hygiene in the spread of infectious diseases. J Sch Nurs 2010;26:33-41.

18. Boone SA, Gerba CP. The occurrence of influenza A virus on household and day care center fomites. J Infect 2005;51:103-9.

19. Westwood JC, Mitchell MA, Legace S. Hospital Sanitation: the massive bacterial contamination of the wet mop. Appl Microbiol 1971;21:693-7.

20. Wang C, Yu E, Xu B et al. Epidemiological and clinical characteristics of the outbreak of 2009 pandemic influenza A (H1N1) at a middle school in Luoyang, China. Public Health 2012;126:289-94.



Regional Experience in Field Epidemiology Training: A Comparative Analysis of the Singapore, US, UK and European Models

INTRODUCTION

Field epidemiology involves having skilled practitioners mounting a timely response to outbreaks through field investigation and quickly implementing appropriate control measures. This activity serves as a cornerstone in safeguarding public health.1 The US Centers for Disease Control and Prevention (CDC) conceived the Field Epidemiology Training Program (FETP) as a way of creating a global workforce of competent field epidemiologists. Modelled after US CDC’s Epidemic Intelligence Service (EIS), the first FETP was set up in Canada in 1976.2,3 Today, this has grown into at least 69 FETPs worldwide,4 all using a set of basic core competencies that focus on collecting data for decision making rather than making decisions based upon intuition.5 As more countries and regions adapt the professional training to meet their local needs and resources, the FETP curriculum becomes different for each FETP.6-8 This customization of the regional experience is to be expected, but very few published articles are available.

The Singapore FETP (S-FETP) was set up to formalize the training of field epidemiologists who would lead public health investigations in Singapore.9 To better understand existing variations beyond Asia, we selected a number of programs for benchmarking that were

felt to be most akin to our current developed country needs. This article aims to provide a comparative analysis of S-FETP with the US, UK and European models to identify common working principles, and the rationale behind differences that exist.

METHODS

Our study was conducted in 2017 as a scholarly project by the Lee Kong Chien School of Medicine, which is a partnership between Nanyang Technological University and Imperial College London. The authors also consulted with counterparts in Public Health England, EPIET and the US CDC in the process.

After outlining key elements of S-FETP, indicators for comparison with other models were derived from the criteria set out in the 2014 CDC Multisite Evaluation of Field Epidemiology Training Program6 as well as indicators found on the CDC website.10 These indicators comprised of rationale and function, hosting organization, course details, admission eligibility, trainee numbers and background, and graduate profiles. Descriptions of the US, UK and European programmes were obtained through a literature review on the MEDLINE (Ovid), PubMed and EBSCOhost databases and from journals such as

Guan Zhong Tan1, Samantha Bracebridge2, Wee Siong Tien3, Minn Thu3, Steven Peng-Lim Ooi3,4

1Lee Kong Chian School of Medicine, 2Health Protection Directorate, Public Health England, 3Public Health Group, Ministry of Health, 4Saw Swee Hock School of Public Health, Singapore



Indicators S-FETP US EIS UK-FETP* EPIET Rationale

Build up field epidemiology capacity

Function Provide on-the-job training for aspiring field epidemiologists while working at the field epidemiology arm of MOH (or an equivalent public health agency), thus fulfilling its public health needs

Hosting Organization Ministry of Health Communicable

Diseases Division

Centers for Disease Control and Prevention

Public Health England (executive agency of

Department of Health)

European Centre for Disease Prevention and

Control Course

Duration 2 years Participants Choice at discretion of the host organization Overlapping

Cohorts No Yes, annual intake

Percentage of Didactic Modules

10 5 ~12 10

Percentage of Field Work

90 95 ~88 90

Mentorship Yes Curriculum

Modules Introductory module, Global health security,

Epidemiology methods, Urban

environmental health, Outbreak

management, Public health leadership, policy and control

Introductory module, Public health surveillance

methods, Advanced epidemiologic

techniques, scientific writing, Preventive

effectiveness methods

Introductory module, Outbreak Investigation , Multivariable Analysis, Rapid Assessment in Complex Emergency

Situations & Sampling, Vaccinology,

Time Series Analysis, Project Review, Environmental

Epidemiology, Lab4Epi, Epidemiology in

healthcare settings

Introductory module, Outbreak Investigation , Multivariable Analysis,

Rapid Assessment in Complex Emergency

Situations & Sampling, Vaccinology,

Time Series Analysis, Project Review

Veterinarian/ Laboratorian

Training

No Yes

Affiliation with

University

No

Post-Course

Alumni Network Activities

Yes

Admission Eligibility Degree-holding MOH employee with one

year of relevant public health experience

Degree in health-related area

(Medicine, Nursing, Veterinarians, Allied

Health and public health-related

discipline)

Masters Degree in epidemiology or public

health or equivalent with prior work within public health and related areas

Masters Degree or equivalent in public

health or related subject with at least

one year of professional practice in

public health or epidemiology and a

thorough knowledge of English and another

official European Union languages

Numbers 5-10 trainees/year 80 officers out of 200 applicants

interviewed /year

6 fellows/year (120 applicants)

19 fellows/year

Recruitment Pool

Ministry staff only Ministry and non-Ministry staff

Ministry and non-Ministry staff

Ministry and non-Ministry staff

Trainee Background

15% Nursing (3/20), 85% Biomedical science (17/20)

70% Physicians, 30% Non-physicians

Variable each year. Backgrounds: Scientists, Public Health Specialty

Registrars, Veterinarians, Public Health Nurses, Environmental Health

Officers

80% Physicians (41/51), 12% Veterinarians (6/51), 8% Others

(Biologist, Pharmacist, social scientist,

research scientist)

Graduate Profile 95% in MOH, with 48% working in CDD

(10/21)

90% work in Public Health

90% work in Public Health 90% work in public health

Table 1. Comparison of salient features in the Field Epidemiology Training Programmes

*UK-FETP, as an EPIET-associated programme, collaborates on running common modules together


Table 2. Criteria for course completion in the Field Epidemiology Training Programmes

S-FETP’s Areas for Assessment

US EIS’s Core Activity for Learning

UK-FETP’s Core Learning Objectives

EPIET’s Core Learning Objectives

Conduct or participate substantially in a field investigation of a potentially serious public health problem that requires a rapid public health response

Design, implement or evaluate a public health surveillance system and deliver a written and/or verbal report on this system as required

Plan, develop and conduct and epidemiological study

Write as first author a scientific manuscript for peer-reviewed journal submission Participate in Public Health Lecture Series and Communicable Diseases Division events

Participate in an EIS conference via oral or poster presentation

Submit abstracts to the Public Health England conference / European Scientific Conference on Applied Infectious Disease Epidemiology

Submit abstracts to the European Scientific Conference on Applied Infectious Disease Epidemiology

Make an oral or poster scientific presentation at an international/regional conference

Make an oral scientific presentation at an international conference

Make an oral scientific presentation at an international conference

Make at least one oral presentation at an international-level, peer-reviewed, English language conference

Write and submit a report to the Epidemiological News Bulletin Quarterly

Write and submit a report to the Morbidity and Mortality Weekly Report

Submit peer-review paper as first author

Prepare a short article in an epidemiological bulletin

Attendance at weekly ‘pow wow’ clinics and teachings

Attendance at classroom teachings



Respond to oral or written public health inquiries


Communicate with media and prepare a FAQ document


Participate in Ministry of Health learning activities

Produce a new learning tool and document reflective notes on one training activity conducted

Prepare and conduct learning activities

Demonstrate the use of multivariable analysis techniques in at least one project.

Exit interview with S-FETP coordinator

Quarterly progress report, midterm review, and Exit interview with FETP coordinator

Exit interview with EPIET coordinators



the American Journal of Epidemiology, International Journal of Epidemiology, Annals of Epidemiology, Epidemiology and Epidemiology Reviews. Google Scholar and Google searches were also utilized. Keywords such as “Field Epidemiology Training Program”, “Epidemic Intelligence Service”, “United Kingdom Field Epidemiology Training Programme”, “European Programme for Intervention Epidemiology Training”, “CDC EIS”, “S-FETP”, “UK-FETP”, “FETP”, “EPIET” were used. Grey literature on programme outline, curriculum and admissions were searched on ProQuest and taken from materials posted on official websites. The four programmes were compared and contrasted with respect to their salient features and criteria for course completion.

. RESULTS

S-FETP was launched in 2010 with its purpose to groom a cadre of public health officers to effectively manage outbreaks and carry out field investigations.11 A two-year programme that runs biennially, follows principles established by the CDC FETP standard curriculum, including the ten core competencies.5 The course begins with a two-week orientation introducing epidemiological methods and other public health concepts relevant to Singapore. Trainees learn on-the-job with time spent doing fieldwork, first under the guidance of mentors and eventually leading outbreak investigations and field studies. Curriculum modules covering global health security, epidemiology methods, urban environmental health, outbreak management, public health leadership, policy and control, are covered through weekly ‘pow wow’ clinic sessions as well as workshops conducted every two to three months.

The Ministry of Health (MOH)’s Communicable Diseases Division (CDD) administers the programme and selects trainees from its public health officers (medical and non-medical) who have at least a year of working experience in public health. Three cohorts have completed S-FETP with 20 graduates from 2012-16, and five trainees are currently in the fourth run. A comparison of the salient features and the criteria for course completion in the Singapore, US, UK and European program are shown in Tables 1 and 2, respectively, and ensuing text summary.

US EIS

The EIS was established in 1951 from the existing operations of a World War II organization charged with controlling malaria at military installations in the United States. While its original aim was to provide infrastructure support and experts to investigate disease outbreak, EIS has now progressed to include


training on chronic non-communicable diseases, injury prevention and control and reproductive health.12 It has produced over 3,614 graduates,13 taking in about 80 participants every year. This is selected from the 200 interviewees out of the 500 applicants yearly.14 Of 564 applicants in 2017, 195 were interviewed and 71 offered positions. The EIS program focuses on training through service, with 95% of learning through conducting field projects. A two-year course that runs annually, the criteria for admission is a graduate degree in a health-related area (Medicine, Nursing, Veterinarian, Allied Health or public health-related discipline).15 Participants must complete the set of Core Activities for Learning which includes conducting investigations and data analysis, scientific writing and effective oral presentation (reference). Upon graduation, more than 90% of the officers work in public health, many under CDC or other health agencies of the US federal government.16

UK-FETP

The UK-FETP was started in 2011 after a report commissioned by Public Health England (then Health Protection Agency) highlighted the need to build up field epidemiology expertise and connect experts together.17,18 Fellows are considered fulltime employees of the Public Health England.7 The UK-FETP is a European Programme for Intervention Epidemiology Training(EPIET)-associated program and thus the curriculum content is based on those found in EPIET.8 10% of the fellowship comprises classroom modules with EPIET fellows. Graduation from the programme requires fellows to achieve a series of core learning objectives.19

EPIET

The EPIET was started in 1995 against a backdrop of the newly established European Union (EU) allowing for large-scale movement of people and goods, which posed a public health threat.20 The program was integrated into the European Centre for Disease Control and Prevention (ECDC) in 2007.21 Criteria for admission is Master’s Degree or equivalent in public health or related subject with at least one year of professional practice in public health or epidemiology and a thorough knowledge of English and another official European Union languages.8 So far, 80% of the fellows are medically qualified (41/51) with 12% being veterinarians (6/51) with the rest being a biologist, pharmacist, social scientist and a research scientist.20 Mentorship is provided via a trainer and two to three training programme coordinators.20 Responding to media and public enquiries, writing and presenting scientific papers at international and regional


conferences, along with attendance at modules are part of the training.20 As of 2008, 161 fellows have graduated and 90% of the 139 fellows interviewed were working in public health at an international, national or regional level.21 Graduation criteria is based on fellows achieving a set of core competencies.22

DISCUSSION

The S-FETP is a young programme that shares many commonalities with the US EIS, UK-FETP and EPIET. They all reside under their respective public health authority, with the program structure fulfilling core objectives of creating competent field epidemiology practitioners. While the four models have each tailored training according to the specific needs of the country, the course duration, curriculum modules, competencies and criteria for completion remain similar.

The variations that exist across programs are part of what defines FETP as a concept and arise due to differing geopolitical and social landscapes as well as country needs and capacities. We noted that participants in the US EIS, UK-FETP and EPIET are drawn from physicians and candidates with a master’s degree in public health or equivalent, S-FETP recruits recent graduates in biomedical sciences. This not only circumvents a local shortage of public health physicians but also allows more economical training of field epidemiologists. At this stage, S-FETP does not have plans to offer special training for veterinarians and laboratorians. The general field epidemiology training has been found to be more useful in Singapore because agencies in the city state form a single tier government with effective collaboration and communication to other sectors through strong One Health coordination.23 Working closely with MOH to safeguard environmental and veterinary public health are the National Environment Agency and the Agri-Food and Veterinary Authority of Singapore.

Our recruitment pool currently draws only on MOH staff who are required to commit full-time to the programme. Part-timers are excluded because of the obligatory rigors and intensity exacted during outbreak periods. In large countries where there is a high demand for field expertise, overlapping cohorts also help ensure a constant supply of field epidemiologists to be deployed to various regions and localities. This is not the case for Singapore which has its own unique public health challenge with limited capacity to train concurrent batches. Instead, resources are focused on one cohort of trainees at any one time to ensure that quality is not compromised.

Overall, S-FETP has been successful in fulfilling the need to build a functional programme in the most cost-efficient manner. The infectious diseases situation is far from static and we are studying introduction of: (1) new training tracks to widen skills upgrading and career progression; (2) additional elements of global outbreak alert and public health response; and (3) a quality programme to add external faculty and improve the in-house pool of trainers. Our future plans also include contributing more towards regional capacity building. As one of the founding members (and current chair) of the ASEAN+3 Field Epidemiology Training Network,24 our innovative novel teaching methods, edutainment (EPiMAN and a training assistant named Debby), and inclusive engagements have received positive feedback from members of the network.

ACKNOWLEDGEMENT

We are grateful to Dr Alden Henderson of the US CDC for his review of this article. He was one of the international trainers for our first S-FETP cohort in 2010, and has maintained a longstanding association with our programme.

REFERENCES

1. Langmuir AD. The epidemic intelligence service of the Center for Disease Control. Public Health Rep 1980;95:470-7.

2. White ME, McDonnell SM, Werker DH et al. Partnerships in international applied epidemiology training and service, 1975-2001. AJE 2001;154:993-9.

3. Music SI, Schultz MG. Field epidemiology training programs: New international health resources. JAMA 1990;263:3309-11.

4. Subramanian R, Herrera D, Kelly P. An evaluation of the global network of field epidemiology and laboratory training programmes: a resource for improving public health capacity and increasing the number of public health professionals worldwide. Hum Resour Health 2013;11.

5. Center for Disease Control and Prevention, United States. Field Epidemiology Training Program Standard Core Curriculum. 2006:3.



6. Jones DGM, Volkov B, Herrera-Guibert D. Multisite Evaluation of Field Epidemiology Training Programs - Findings and Recommendations. 2014:1-3.

7. Public Health England, United Kingdom. Field Epidemiology Training Programme prospectus. 2015. p. 4.

8. Aftab JMM, Bohlin A, Jung H et al. Manual for the ECDC Fellowship Programme - EPIET and EUPHEM paths, Cohort 2017. European Center for Disease Prevention and Control, Stockholm: European Center for Disease Prevention and Control; 2016.

9. Ooi PL, Seetoh T, Cutter J. The Singapore field epidemiology service: Insights into outbreak management. J Prev Med Public Health 2012;45;277-282.

10. Centers for Disease Control and Prevention, United States. FETP Programmatic Indicators. 2007.

11. Ho M, Zubaidah S, Ooi PL. Pushing Surveillance and Response Boundaries: The Singapore Field Epidemiology Experience. Singapore Epidemiol News Bull 2017;43:81.

12. Koplan JP, Thacker SB. Fifty years of epidemiology at the Centers for Disease Control and Prevention: Significant and consequential. Am J Epidemiol 2001;154:982-4.

13. Schneider D, Evering-Watley M, Walke H et al. Training the global public health workforce through Applied Epidemiology Training Programs: CDC’s experience, 1951–2011. Public Health Reviews 2011;33:190-203.

14. Association of American Medical College. CDC's Epidemic Intelligence Service (EIS): A unique fellowship for physicians, Question and Answer session 2016. Available at https://www.aamc.org/download/456768/data/eismarch2016qa.pdf (accessed on 29 November 2017)

15. Centers for Disease Control and Prevention, United States. Epidemic Intelligence Service: Application Information, Eligibility (updated June 5, 2017). Available at https://www.cdc.gov/eis/application.html (accessed on 1 September 2017)

16. Thacker S, Dannenberg A, Hamilton D. Epidemic Intelligence Service of the Centers for Disease Control and Prevention: 50 years of training and service in applied epidemiology. Am J Epidemiol 2001;154.

17. Public Health England, United Kingdom. Review of Epidemiology in the Health Protection Agency - A Report for the Health Protection Agency Board. 2008.

18. Public Health England, United Kingdom. Essential entry criteria for Field Epidemiology Training Programme Fellowship. 2015. p. 1.

19. Public Health England, United Kingdom. UK Field Epidemiology Training Programme Core Learning Objective. 2012.

20. Van Loock F, Rowland M, Grein T et al. Intervention epidemiology training: a European perspective. Euro Surveill 2001;6:37-43.

21. Bosman A, Schimmer B, Coulombier D. Contribution of EPIET to public health workforce in the EU, 1995-2008. Euro Surveill 2009;14: 1-5.

22. European Centre for Disease Prevention and Control, European Union. Core Competencies for EPIET Fellows (updated 2015). Available at https://ecdc.europa.eu/sites/portal/files/media/en/epiet/Documents/Other%20documents/Annex%2001_EPIET%20Core%20comptencies%20_2016_updated.pdf (accessed on 5 September 2017)

23. Degeling C, Johnson J, Kerridge I et al. Implementing a One Health approach to emerging infectious disease: reflections on the socio-political, ethical and legal dimensions. BMC Public Health 2015;15:1307.

24. Ministry of Health, Singapore. Strengthening the Field Epidemiology Training Network. Singapore Epidemiol News Bull 2017;43:101-4.



Working with Warriors in Malaria Control

NOTES FROM THE FIELD


Think we have no problems with malaria? Think again! Introducing Singapore's Malaria Knowledge Retention programme...

Reported by Charlene Tow, Cherie See

Communicable Diseases Division, Ministry of Health



INTRODUCTION

Malaria is an infection by the Plasmodium parasite transmitted through the bite of an infective female Anopheles mosquito vector. Although Singapore has been certified malaria free by WHO since 1982, our city state remains receptive to its reintroduction due to the presence of the mosquito vectors, albeit at relatively low levels. Despite intensive control measures, a number of malaria receptive areas remain. Disease surveillance and control is shared by two public health agencies – MOH which is responsible for case surveillance and epidemiological investigation, and NEA which undertakes integrated vector surveillance and control comprising environmental management and source reduction.

A dedicated team of NEA officers routinely search for the Anopheles mosquito in areas with environmental conditions conducive for vectors to breed. All larvae and pupae detected are collected and identified at

the Environmental Health Institute. As part of the efforts to keep Anopheles population low, the officer needs to to be able to distinguish them from the other mosquitoes. To sustain ability to keep malaria out, the Malaria Knowledge Retention programme was initiated to ensure that expertise built up over the years are not lost when the current pool of experts reach retirement age, as well as tackle new challenges posed by the evolving vector status of our local mosquitoes. Our experience of the programme is detailed below.

DAY 1: SITE VISIT TO ENTOMOLOGY LABORATORY

Before the programme started outfield, it was necessary for the participants to understand the Anopheles mosquitoes. For this, we had the opportunity to visit the Environment Health Institute (EHI). The malaria vectors in Singapore were identified as Anopheles epiroticus (previously known as Anopheles sundaicus), Anopheles maculatus and Anopheles letifer. Anopheles sinensis has also recently been incriminated

Figure 1. (a) Studying Anopheles larvae in a container; (b) Anopheles adults resting at an angle to a surface. (c) Aedes adults resting parallel to surface

ba b

c




to be a malaria vector. Amongst the four species, An. epiroticus and An. sinensis are the two most commonly found Anopheles vectors found in Singapore. Both anopheles' species colonies are available in EHI. All Anopheles larvae do not have a siphon - the "breathing tube" and move or rest parallel to the water surface

(Figure 1). However, when disturbed, the Anopheles larva moves quickly to the buttom in a random manner. In comparison, Aedes larvae breathe through siphon and move in the water in an S-shaped fashion, but it is much harder to pick up Anopheles larvae compared to Aedes because they are faster and stay at the buttom

Figure 2. (a) Setting up the HBNT at a suitable location; (b) Human baits get inside the inner net.

Species Anopheles epiroticus Anopheles letifer Anopheles maculatus Anopheles sinensis Habitats Rural (coastal)

Breeds in sunlit brackish pools with algae

Bites during the night

Rural (coastal) Breeds in fresh

to slight brackish water


Rural (forested) Breeds in seepages

and small streams exposed to partial sunlight


Rural Breeds in grassy

pools exposed to partial or complete sunlight


Table 1. Breeding habitats of the Anopheles mosquito species in Singapore

Source: National Environment Agency

a

b


longer! The adult An. sinensis and An. epiroticus are brown, unlike Aedes which has a characteristic white and black pattern. They tend to rest at 45o on any wall, compared to an Aedes which rests parallel to the surface. Breeding habitats for the different types of Anopheles species were also explained to us (Table 1).

DAY 2: NIGHT TRAPPING OPERATIONS

When Anopheles breeding is detected, this calls for larviciding with insecticides and source reduction to target the immature stages of the vector. In the event of malaria transmission, thermal fogging and residual spraying may be conducted to kill the adults that may be present in the vicinity. Effectiveness of vector control is assessed by adult trapping at night

using human bait and light traps, both of which are performed routinely as part of malaria surveillance.

Participants were taught how to set up the human baited net trap (HBNT). The traditional bare leg catch method, where mosquitoes are collected when landing on exposed lower legs, is still considered the “gold standard” as a trapping method for Anopheles vector but it can potentially expose officers to infective mosquitoes! HBNT consists of two box nets, one protecting the human bait and the outer larger net placed over the inner net. The outer net is open so that mosquitoes attracted to the human bait are collected between the two nets. A light source is placed above the human to attract the mosquitoes as well (Figure 2). Participants were also taught how to set-up the

Figure 3. (a) Trainer explaining how the Night Catcher is set-up for light trapping of mosquitoes; (b) Participants learning how to set up the catcher on their own.

a b



Night Catcher, an in-house device improvised from the US CDC light trap, enabling hourly collection of mosquitoes using incandescent light and dry-ice as attractants (Figure 3). The advantage of the Night Catcher system is that it is automated, requiring no human supervision and thus reduces human risk of contracting vector-borne diseases.

Once the traps were set-up, participants were ready to start their night shift from 7pm to 10am the next morning. A pair of participants would be seated for an hour inside the HBNT, after which another pair will collect the mosquitoes from the outer surface of the inner net, using test tubes and gloves. Highest mosquito activity was between 8 and 10 pm, when most of them were collected. It was a real challenge to recognize and differentiate Anopheles from Culex

Figure 4. (a) Collecting mosquitoes from the HBNT; (b) Cherie checking the night catcher!

mosquitoes and other insects in the dark as well as catching them alive with a test tube (Figure 4).

DAY 3-5: HUNT FOR THE ANOPHELES!

Participants were given an opportunity to look for Anopheles larvae in real-life situations. We were brought to malaria receptive areas, areas with brackish water (mixture of fresh and salt water) to try collecting larvae. Improvised dippers were provided to get a sample of the Anopheles larvae. The larvae is known to dive into the water once the water is disturbed. Therefore, the dippers were specially modified to be extendable and wide to make a quick dip.

Many challenging terrain had to be overcome while searching for Anopheles larvae (Figures 5 and 6). For example, our visit to a fish farm revealed the

a b



Figure 5. (a) Using boots and knife to move through the terrain; (b) Searching for larva in a huge drain; (c) Surmounting the hilly terrain to get to breeding sites


a b

c


difficulties of inspecting a huge area for breeding sites while managing the site owner’s expectation! We also discovered the use of environmental management of vector breeding sites. Surface drains and subsoil pipes had been laid in areas with seepage water from a hilly terrain to prevent stagnation of water.

It was definitely an experience to look for Anopheles mosquitoes in Singapore. Hornet sting, ant nest, snake encounter - just some of the hazards on the job that our trainers related to us from their past encounters. One of our trainers who had decades of experiences in looking for Anopheles mosquitoes showed us his skills when he caught the larvae with just one scoop of the dipper despite out failed attempts dipping at the same water spot for the past 15 minutes! It definitely takes passion, skills, and experience to be a malaria warrior.

Special acknowledgement to NEA’s Muhammad Farhan Bin Rahman, Ahmad Khair Bin Abdul Aziz, Tuan Qurthubi Bin Tuan Isa, Izzardi Bin Junadi, Abdul Azim Bin Abdul Rahim, Zheng Junyuan, Dr Pang Sook Cheng for all their kind assistance!

Figure 6. (a) Differentiating larvae in a sample tube; (b) It is the Anopheles!

REFLECTIONS AND CONCLUSION

Despite the periodic occurrences of small localised transmission, malaria has not re-established itself as an endemic disease. Malaria control is a lot about hard work and it is thus important to retain institutional memory of lessons learned from past experiences. Dr Pang and his co-researchers have also found that Singapore's Anopheles sinensis is susceptible to Plasmodium vivax isolates from the western Thailand - Myanmar border (Malaria Journal 2017;16:465).

We understand that Singapore remains both receptive and vulnerable to the reintroduction of malaria – receptive despite the low Anopheles vector population, and vulnerable because of the large influx of travellers and foreign workers from the endemic regions. Each introduction has been completely eliminated through epidemiological surveillance and epidemic vector control operations. Vigilance over the disease and vector situation should never be compromised.

a b



FAST FACTS


As of E Week 26 (24-30 Jun 2018)Infectious Diseases Update

SURVEILLANCE SUMMARY

* Preliminary figures, subject to revision when more information is available.

E-Week 26 Cumulative first 26 Weeks

2018* 2017 Median 2018 2017 Median2013 -2017 2013 -2017

FOOD/WATER-BORNE DISEASESAcute Hepatitis A 0 2 2 35 45 43 Acute Hepatitis E 0 1 1 32 27 29 Campylobacteriosis 7 13 7 197 198 207 Cholera 0 0 0 1 1 0 Paratyphoid 0 0 0 7 10 14 Poliomyelitis 0 0 0 0 0 0 Salmonellosis 31 28 41 814 1040 978 Typhoid 1 1 1 16 36 36 VECTOR-BORNE DISEASESChikungunya Fever 0 2 1 4 12 16 Dengue Fever 75 75 242 1365 1425 8647 Dengue Haemorrhagic Fever 1 0 0 14 9 10 Japanese Encephalitis 0 0 NA 0 0 NA Leptospirosis^ 0 0 NA 0 26 NA Malaria 1 1 1 16 14 20 Murine Typhus 0 0 NA 0 0 NA Nipah virus infection 0 0 0 0 0 0 Plague 0 0 0 0 0 0 Yellow Fever 0 0 0 0 0 0 Zika Virus Infection 0 1 NA 1 47 NA AIR/DROPLET-BORNE DISEASES Avian Influenza 0 0 NA 0 0 NA Diphtheria 0 0 0 0 0 0 Ebola Virus Disease 0 0 NA 0 0 NA Haemophilus influenzae type b 0 0 0 3 5 4 Hand, Foot And Mouth Disease 889 436 455 21675 17661 15811 Legionellosis 0 1 0 9 11 11 Measles 0 2 1 25 48 48 Melioidosis 1 4 2 15 28 24 Meningococcal Disease 0 0 0 4 5 3 Mumps 7 12 10 268 266 258 Pertussis 1 1 0 65 28 27 Pneumococcal Disease (invasive) 1 2 4 64 78 75 Rubella 0 1 1 1 6 10 Severe acute respiratory syndrome 0 0 0 0 0 0 Tetanus 0 0 0 1 0 OTHER DISEASESAcute hepatitis B 0 1 0 25 17 26 Acute hepatitis C 0 1 1 8 7 6 Botulism 0 0 NA 1 0 NA POLYCLINIC ATTENDANCES - AVERAGE DAILY NUMBERAcute upper respiratory infections 2987 2793 2413 NA Acute conjunctivitis 87 84 83 NA Acute Diarrhoea 603 617 493 NA Chickenpox 16 19 NA NA HIV/STI/TB NOTIFICATIONS 2018 May Cumulative 2018HIV/AIDS 17 122 Legally Notifiable STIs 833 4237 Tuberculosis 153 679

^ Updated case counts due to change in case definitions w.e.f 1 Jan 2018



Influenza Surveillance

Average daily number of patients seeking treatment in the polyclinics for Acute Respiratory Infection (ARI) peaked in May and declined to below the 70th percentile in June. The proportion of patients with influenza-like illness (ILI) among the polyclinic attendances for ARI is 1.5%. Overall positivity rate for influenza among ILI samples (n=208) in the community was 24.5% in the past 4 weeks. Of the specimens tested positive for influenza in June 2018, these were positive for influenza A (H1N1)pdm09 (81.1%), influenza B (9.4%), and influenza A (H3N2) (7.5%).


Dengue Surveillance

The number of dengue notifications remained low, well below the mean + 1 standard deviation (SD) level, from April to June. Preliminary results of all positive dengue samples serotyped in June 2018 showed DEN-1, DEN-2, DEN-3 and DEN-4 at 16.7%, 37.5%, 33.3% and 12.5%, respectively.

Zika Surveillance

As of 30 June 2018, there was 1 case of Zika reported. There were 67 cases reported in 2017.



Surveillance of Other Selected Diseases


Typhoid

Paratyphoid

Hepatitis A


ENB Quarterly is published in Jan, Apr, Jul and Oct every year by the Ministry of Health, Singapore. Readership includes physicians, epidemiologists, microbiologists, laboratorians, researchers, scientists, and public health practitioners. Correspondence address: The Editor (ENB Quarterly), Public Health Group, Ministry of Health, 16 College Road, College of Medicine Building, Singapore 169854. A downloadable electronic format is provided free of charge at our website: https://www.moh.gov.sg/content/moh_web/home/Publications/epide-miological_news_bulletin.html Contribution by authors of articles to ENB Quarterly is a public health service and does not preclude subsequent publication in a scientific peer-reviewed journal. Opinions expressed by authors do not neces-sarily reflect the position of the Ministry. The material in ENB Quarterly may be reproduced with proper citation of source as follows: [Author]. [Article title]. Epidemiol News Bull [Year]; [Vol]:[inclusive page numbers]

Summary statistical data provided in ENB Quarterly are provisional, based on reports to the Ministry of Health. For more current updates, please refer to our MOH Weekly Infectious Diseases Bulletin: https://www.moh.gov.sg/content/moh_web/home/statistics/infectiousDiseas-esStatistics/weekly_infectiousdiseasesbulletin.html

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EDITORIAL BOARDSteven Ooi, Chair

Jeffery CutterLalitha Kurupatham

Stefan Ma

PUBLICATION TEAMChan Pei Pei

Khine NandarNigel ChongSee Wanhan

Tien Wee SiongZul-Azri

ADVISORY PANELDerrick Heng, Group Director

Vernon Lee, Communicable DiseasesLyn James, Epidemiology & Disease Control

External AdvisorsCharlene Fernandez

Dale FisherHsu Li Yang

Irving BoudvilleLim Poh Lian

Nancy TeeRaymond Lin

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