-Influenza-epidemiology,prevention and control
-
Upload
shubhanshu-gupta -
Category
Health & Medicine
-
view
310 -
download
1
description
Transcript of -Influenza-epidemiology,prevention and control
1
INFLUENZA Epidemiology, Prevention and Control
SPEAKER:- Shubhanshu GuptaTEACHER I/C:- Dr.Dheeraj MahajanDATE:- 09/09/2014
2
Contents1. History
2. About the disease and types
3. Epidemiological trends
4. Prevention and Control.
5. Pandemic Influenza(h1n1) 2009
6. Special-avian Influenza(outbreaks).
7. Newer vaccines and strains.
3
History of influenza
• 412 BC - first mentioned by Hippocrates
• 1580 - first pandemic described
• 1580-1900 - 28 pandemics
4
Discovery of Influenza Virus
• First isolated from a pig in 1931 (swine flu)
• Isolated from human in 1933
5
WHAT IS INFLUENZA?(ALSO KNOWN AS THE FLU)
• The flu is a contagious respiratory illness
• It is caused by influenza viruses
• It can cause mild to severe illness and at times can lead to death
• It can be prevented by getting the flu vaccination each year
6
Influenza: A Viral infection• Acute respiratory infection caused by Influenza virus
– Three types A, B and C.
• Currently viruses circulating in human population – Influenza A (H3N2), A (H1N1) and B Strains.
• All known pandemics (global outbreaks) were caused by Influenza A.
• Animal influenza viruses may affect humans in special circumstances – Bird Flu: A (H5N1).
7
Naming influenza viruses
A/Hong Kong/156/97 (H5N1)
StrainID
Hemagglutinin NeuraminidaseType
Origin Yearisolated
16 9
8
Influenza types
Type A Potentially severe illness
Epidemics and pandemics
Rapidly changing
Type B Usually less severe illness
Epidemics
More uniform
Type C Usually mild or asymptomatic illness
Minimal public health impact
9
Classification of Influenza virus
• Classified on the basis of hemagglutinin (HA) and neuraminidase (NA).
• 16 subtypes of HA and 9 subtypes of NA are known to exist in animals (HA 1-16, NA 1-9).
• 3 subtypes of HA (1-3) and 2 subtypes of NA (1-2) are human influenza viruses. HA 5, 7, 9 and NA 7 can also infect humans
10
Epidemiology
• Worldwide distribution
• Outbreaks usually occur suddenly.
• Flu spreads through communities resulting in an epidemic. Cases tend to peak after about 3 weeks and begin to subside after another 3-4 weeks
11
Causative Agent of Influenza
• Caused by a virus belonging to the MYXOVIRUS group which comprises of Orthomyxovirus and Paramyxovirus
• Influenza virus is an Orthomyxovirus
Influenza A Virus Structure• Hemagglutinin (HA)
– Receptor binding (sialic acid)– Membrane fusion– Neutralizing antibody target
• Neuraminidase (NA)– Remove sialic acid residues– Virion release
• Ion channel (M2)– H+-dependent uncoating– Influenza A only
• Influenza A subtypes based on HA (16) and NA (9)
– H1N1, H3N2– A/Hong Kong/8/68
12
13
Influenza Antigenic Changes• Antigenic Shift
– major change, new subtype– caused by exchange of gene segments– may result in pandemic
• Example of antigenic shift– H2N2 virus circulated in 1957-1967– H3N2 virus appeared in 1968 and completely
replaced H2N2 virus
14
• Antigenic Drift– minor change, same subtype– caused by point mutations in gene– may result in epidemic
• Example of antigenic drift– in 2002-2003, A/Panama/2007/99 (H3N2) virus
was dominant– A/Fujian/411/2002 (H3N2) appeared in late 2003
and caused widespread illness in 2003-2004
15
Priority Groups/CDC Recommendations
• People 65 years of age and older• People 2-64 years with chronic health
conditions• Children 6-23 months• Pregnant women• Healthcare personnel who provide direct
patient care• Household contact and out-of-home
caregivers of children less than 6 months of age
16
Epidemiology cont.
• Peak season is November through March
• Each year about 10 to 20% of indians develop influenza
• Overcrowding enhances transmission.
Seasonality Incubation period• Time from exposure to onset of symptoms• 1 to 4 days (IQ range = 2-3 days)• Peak shedding first 3 days of illness
Seasonality• In temperate zones, increases in winter months
– Driven by mutations and viral preference for cold, dry weather conditions
• In tropical zones, circulates year-round – Fall-winter and rainy season increase has been observed– More international data is needed
27
18
Northern hemisphere
Southern hemisphere
Tropics
Influenza activity peak: November-March2,3
.
Influenza activity peak: April-September4,5
Year-round activity3,4
0
2
4
6
8
10
1 3 5 7 9 11 13 15 40 42 44 46 48 50 52Week
0
10
20
30
40
50
J F M A M J J A S O N DMonth
ILI/
1000
Pop
ulati
onIL
I/10
00 P
opul
ation
20
0
4
8
12
1618
2
6
10
14
1 5 9 13 17 21 25 29 33 37 41 49Week
45
ILI C
onsu
ltatio
ns/
1000
Pop
ulati
on
Influenza spread occurs inseasonal patterns
E.g. India
19
Karnataka
Andhra Pradesh
Maharashtra
Orissa
Gujarat
Rajasthan
Madhya Pradesh
Uttar Pradesh
Jharkhand
Jammu Kashmir
Punjab
Chattisgarh
Uttaranchal
Himachal Pradesh
Haryana
Bihar
New Delhi
Tamil NaduKerala
West Bengal
Sikkim
Arunachal Pradesh
Assam Nagaland
Manipur
Tripura
Mizoram
Meghalaya
• Location: Chennai (22nd Feb-22nd March 2008) Total Sample Collected : 55 Samples Total No. of Sample +ve : 23 Samples % + ve : 41.82 % +ve Influenza A :13 Samples (56.5%) Influenza B : 10 Samples (43.3%)
MONTHLY INFLUENZA ACTIVITY REPORTED BY-INDIAN SENTINEL DOCTOR’S NETWORK FEB-MAR 2008
No Report
• Location: Delhi ( Jan- Mar 2008 ) Total Sample Collected :86 samples Total No. of Sample +ve :12 Samples % +ve :14%+ve Influenza A/H1N1 : 6 Samples Influenza B : 4 Samples Not determined but +ve : 2 Samples
Source: Sentinel Doctor’s Network,March 2008
> 10 % positvity
> 40% positivity
20
March- April August - October
21
India 2011
Influenza virus circulation peaks in June-August
J J A S
22
Global surveillance network:
106 Member countries136 NIC6 WHO CCS4 ERLS11 H5 Ref Labs
23
Influenza Activity And Peaks
24
WHO National Influenza Center(as of April 2011)
• Pune (NIV),• Kasauli (CRI)• Mumbai(Haffkine
Institute)
25
Influenza: Transmission• Incubation period: 1-4 days, average 2 days.
• Transmission may start 1 or 2 days before onset of symptoms and last for a
week.
• Immunocompromised patients may transmit the virus for up to a month
after onset of symptoms .
• Virus particles spread through coughing and sneezing .
• One infectious particle can generate up to 1,000 virus particles.
26
Influenza transmission is by 3 ways :
1. Direct transmission into the mucous membrane of a person .
2. Airborne route – that is via droplets .(0.5-5 µm diameter)
3. Contaminated surfaces, handles etc…
27
28
Common Symptoms
• Respiratory disease• Abrupt onset of symptoms• Fever (up to 104° F)• Chills (sometimes shaking)• Muscle aches and pains• Sweating• Dry Cough• Nasal congestion• Sore throat• Headache• Malaise• Fatigue
29
Influenza Pathogenesis
• Respiratory transmission of virus
• Replication in respiratory epithelium with subsequent destruction of cells
• Viremia usually not demonstrable
• Viral shedding in respiratory secretions for 5-10 days
Laboratory Testing for Influenza
• Rapid diagnostic tests Can provide results
<30 minutes ~ 70+% sensitive,
90+% specific
• SerologyMust used paired
serum samples>2 week delay for
results
30
.Viral culture Gold standard Results take 7 days Influenza isolates for yearly vaccine
development
.RT-PCR Most sensitive Becoming more widely available
.Immunofluorescence Requires intact cells and laboratory
skill/experience
31
CDC swab kit availableMethod: horizontal, away from nasal
septum
32
Influenza Complications
• Pneumonia– primary influenza– secondary bacterial
• Reye syndrome
• Myocarditis• Guillian barre syndrome
• Death ~0.5-1 per 1000 cases
33
PREVENTION and CONTROL OF INFLUENZA
34
Importance of the Early Treatment
35
Infection control at Individual level• Respiratory Hygiene / Cough Etiquette
– Cover the nose/mouth with a handkerchief/ tissue paper when coughing or sneezing
– Use tissues to contain respiratory secretions and dispose of them in the nearest waste receptacle after use
• Hand hygiene – Hand washing with non-antimicrobial soap and water,
alcohol-based hand rub, or antiseptic hand wash after having contact with respiratory secretions and contaminated objects /materials
• Use of mask– Three layered surgical mask– For cases and immediate family and social contacts.
36
Personal Protective Equipment(PPE)
37
N-95 Filtering Masks• Protect from inhalation
of airborne particles.
• Fit tightly to face.
• Approved by NIOSH.
• Particles<100µm.
38
• Protect from spit and mucous discharges in procedures only.
• Do not have adequate filtering.
• Do not pass the fit test.• Approved by FDA.
Droplet precautions: Surgical Masks
39
Isolation Precautions
Cough etiquette
• Respiratory etiquette– Cover nose / mouth when
coughing or sneezing
• Hand washing!
40
41
Prevention of Swine Flu
42
Control Measures
• Immunoprophylaxis with vaccine• Chemoprophylaxis and
chemotherapy
43
Influenza Vaccines• Inactivated subunit (TIV)
– intramuscular– trivalent– split virus and subunit types– duration of immunity 1 year or less
• Live attenuated vaccine (LAIV)– intranasal– trivalent– duration of immunity at least 1 year
46
45
Vaccination Schedules
* 2 doses at least 1 month apart for children receiving vaccine for the first time
Age group Dosage (im/sc) No. of doses
6-35 months 0.25 ml 1 or 2*
3-8 years 0.5 ml 1 or 2*
> 9 years 0.5 ml 1
46
•Live viruses with limited replication in the upper respiratory tract
•Prevents (>90%) disease symptoms
•Limited use: Only approved for people 5 to 49 years old in good
health condition
•Children between 5 and 8 years old: two doses with an interval of 60
days (if not previously vaccinated with Flumist®)
.Expensive ($70?) Cold adapted influenza viruses:
ca A/Ann Arbor/6/60 (H2N2)
ca B/Ann Arbor/1/66
Flumist®: Efficacy and limitations
47
Fluzone Intradermal
• Licensed by FDA in May 2011• Approved only for persons 18 through 64 years
of age• Dose is 0.1 mL administered in the deltoid area
by a specially designed microneedle and injector system
• Formulated to contain more HA (27 mcg) than a 0.1 mL dose of regular Fluzone formulation (9 mcg)
48
Fluzone TIV Formulations
Formulation (age) HA per dose• Adult (>36 mos) - 45 mcg/0.5 mL• Pediatric (6-35 mos) - 22.5 mcg/0.25 mL• High dose (>65 yrs) - 180 mcg/0.5 mL• Intradermal (18-64 yrs) - 27 mcg/0.1 mL
49
50
Nasal Spray Vaccine
• Live, attenuated vaccine administered by nasal spray.
• Option for those healthy people ages 2 to 49 years old.
• Option for health care workers who take care of sick persons or care for babies under 6 months of age and who are healthy between 2 and 49 years of age.
• Not to be used in pregnancy.
• Not to be used by those who care for or live with someone with a compromised immune system or children less than 2 years of age.
51
Comparison of Influenza Vaccines
Vaccine type Composition Immunogenicity Reactogenecity
Whole-virus (no longer used)
Whole virus +++ +++
Split-virion Surface proteins, nucleocapsid and matrix proteins
++ ++
Subunit Surface proteins ++ +
Virosomal Surface proteins plus virosomes
++ +
Adjuvanted Surface proteins plus adjuvant
+++ ++
Intradermal (subunit)
Surface proteins +++ ++
+Low; ++ Medium; +++ High.
52
Who Should Not be Vaccinated?
• Those with severe allergy to chicken eggs• Those who have had a severe reaction to a flu
vaccine in the past• Those who have developed Guillain Barre
Syndrome within 6 weeks of getting a flu vaccine previously
• Children less than 6 months of age• Those who have a moderate or severe illness
with fever (May return for the vaccine when symptoms lessen)
53
. Medical conditions like Asthma, heart disease Blood disorders like sickle cell anaemia Liver disorders , kidney disorders Endocrine disorders like diabetes mellitus. Metabolic disorders ( inherited metabolic disorders
or mitochondrial isorders) Immunocompromised states – HIV/AIDS;
prolonged steroid therapy; malignancies. Morbidly obese (BMI > 40) Long term aspirin therapy.
Vaccine InformationAdverse Events
Intramuscular Injection (TIV)• Local Reactions:
pain 20-50% redness 10-13%swelling 6-8%
• Muscle aches: 18-30%• Headache: 14-30%• Malaise: 14-22%• Fever: 2-3%• Allergic reactions:
<1 in 1 million• Guillain Barre Syndrome:
1 in 1 million.
Intradermal (ID)• Local Reactions:
redness 76%hardness 58%swelling 57%pain 51% itching 47%
• Systemic side effects: similar to TIV
Nasal Spray (LAIV)• Local Reactions:
cough 14% runny nose 45%sore throat 28%chills 9%
54
55
Antivirals drugs
• M2 ion channel inhibitors:
– Amantadine– Rimantidine
• Neuraminidase inhibitors:
– Tamiflu™ (oseltamivir)-in the form of pills/tablets– Relenza® (zanamivir)-in the form of inhaled
powder
56
57
What is Pandemic Influenza?• Pandemic influenza is a respiratory (or breathing)
illness that is new to humans and can make them very sick.
• It happens about 3 times per century and spreads around the world, killing many people and making many people sick.
• Pandemic influenza also causes many serious problems in municipalities, such as problems with food, water, and electricity.
58
The new virus must be efficiently transmitted from one human to another
Prerequisites for pandemic influenza
A new influenza virus emerges to which the general population has little/no immunity
The new virus must be able to replicate in humans and cause disease
Human Influenza – A public health problem
each year
– Usually some immunity built up from previous exposures to the same subtype
– Infants and elderly most at risk
– Result of Antigenic Drift
Influenza Pandemics– Appear in the human
population rarely and unpredictably
– Human population lacks immunity to a new influenza A virus subtype
– All age groups, including healthy young adults, may be at increased risk for serious complications
– Result of Antigenic Shift59
Seasonal Epidemics vs. Pandemics
60
What is H1N1?• A new virus that emerged in 2009 in Mexico City
and quickly spread across the globe.
• H1N1 declared a pandemic in June 2009.Initially referred to as “swine” influenza because the virus was found to contain genetic material from swine influenza A strains, as well as avian and human strains.
-A human virus, and people get it from people – not from pigs. During 2011 India reported 603 cases,275 deaths, case fatality rate=12.44%.
61
Case definitions for pandemic Influenza
• Suspected case: with onset in 7 days of close contact OR within 7 days of travel to community OR residing in community with a confirm case of pandemic influenza A.
• Probable case: suspected case + positive for influenza A by immunofluorescence assay.
• Confirmed case: laboratory confirmed pandemic influenza A case by: RT-PCR,VIRUS CULTURE and FOUR FOLD RISE IN ANTIBODY TITRE.
62
STARTMarch 2009
April 2009
May 2009
Pandemic H1N1 rapidly spread worldwide: May 2009
29 May *, 15,510 cases including 99 deaths reported by 53 countries
1-1011-50
51–500
500-5,000
Cumulative cases
>5,000
63
Pandemic influenza in the 20th Century
1920 1940 1960 1980 2000
H1N1 H2N2 H3N2
1918 “Spanish Flu” 1957 “Asian Flu” 1968 “Hong Kong Flu”
20-40 million deaths 1 million deaths 1 million deaths
64
Pandemic Phases
65
WHO Pandemic Phases and Currently Circulating Novel
Viruses• H1N1
– April 25, 2009: Declaration of a Public Health Emergency of International Concern
– April 28, 2009: WHO declares Phase 4– April 29, 2009: WHO declares Phase 5– June 11, 2009: WHO declares Phase 6
• H5N1– First human cases reported 1997– Increase in reports of human cases began in 2003– WHO Phase 3
66
Pandemic Precautions
• If a pandemic occurs:– Avoid crowded conditions and close contact with
other people – Consider wearing respirators or other protective
equipment– Follow good hygiene measures– Practice social distancing– Quarantine ill individuals– Vaccination
67
What is Avian Influenza (Bird Flu)?• It is a disease that spreads from bird to bird, causing
some birds to become very sick or die.
• It can spread from birds to humans, but not easily.
• It is not yet capable of spreading from human to human except in very rare cases.
• There is a risk that it could become pandemic influenza, but this has not happened yet with the type of bird flu that has recently killed so many chickens.
– Direct and close contact with sick or dead poultry.• Visiting a live poultry market.
– No evidence of sustained person-to-person spread.
– Limited probable person-to-person spread.
37
Human H5N1 Epidemiology
69
Pathogenicity • High pathogenicity avian influenza (HPAI)
– Causes severe disease in poultry– Contains subtypes H5 or H7
• Low pathogenicity avian influenza (LPAI)– Causes mild disease in poultry– Contains other H subtypes
• Includes non-HPAI H5 and H7.
• LPAI H5 or H7 subtypes can mutate into HPAI.
Worldwide H5N1 Outbreak in Humans: 2003 - 2007
39
71
Avian Influenza (outbreaks)
• In 2003, the avian influenza virus strain H7N7 occurred in poultry farms in the Netherlands, spreading to Germany and Belgium. Infection, mainly conjunctivitis occurred in 83 humans with 1 death. The outbreak was controlled by destroying over 30 million domestic poultry.In 2003, the avian influenza virus, H9N2 was identified in a child in Hong Kong with influenza who recovered.
• 2011- 62 cases in cambodia,indonesia,china,bangladesh.
72
Newer strains and vaccines for Influenza
• Influenza A (H1N1)– Retain current vaccine strain A/California/7/2009 (H1N1)-like virus.
• Influenza A (H3N2)– Replace current vaccine strain A/Victoria/361/2011 (H3N2) - like virus
with an A(H3N2) virus antigenically like the cell-propagated prototype virus A/Victoria/361/2011.
• Influenza B– Replace current vaccine strain with a B/Massachusetts/2/2012-like virus
(B/Yamagata lineage)– Retain current B/Wisconsin/1/2010 - like virus (B/Yamagata lineage)– Replace current vaccine strain with an alternative candidate vaccine virus
from the B/Victoria lineage
73
Recent Influenza Vaccine Approvals
• Fluarix QuadrivalentDecember 14, 2012
• First licensed quadrivalent inactivated influenza vaccine to prevent seasonal influenza
• For use in persons ages 3 years and older• Contains four strains of the influenza virus, two influenza A
strains (H1N1 and H3N2) and two influenza B strains (Yamagata and Victoria lineages)
• Flublok– January 16, 2013
• Trivalent vaccine• First licensed influenza vaccine manufactured using an
insect virus (baculovirus) expression system and recombinant DNA technology
• For use in persons ages 18 through 49.
74
Influenza Vaccine Presentations 2011-2012
Vaccine Dose form AgeFluzone TIV(sanofi pasteur)
SDS, SDV, MDV
6 months and older
Fluarix TIVFluLaval TIV(GSK)
SDSMDV
3 years and older18 years and older
Fluvirin TIV(Novartis)
SDS, MDV 4 years and older
Afluria TIV(CSL)
SDS 9 years and older
Flumist LAIV(MedImmune)
Nasal spray 2-49 years (healthy, nonpregnant)
SDS=single dose syringe; SDV=single dose vial; MDV=multidose vial SDS=single dose syringe; SDV=single dose vial; MDV=multidose vial
75
WHO Recommended strains 2011 -12 season
• It is recommended that vaccines for use in the 2011-2012 influenza season (northern hemisphere) contain the following:
an A/California/7/2009 (H1N1)-like virus;
an A/Perth/16/2009 (H3N2)-like virus;
a B/Brisbane/60/2008-like virus. 2011-12 season WHO recommended strain are similar to 2010-11 season
northern hemisphere strains
2009
-10
2010
-11
2011
- 12
Brisbane
Brisbane
Brisbane
BA/H3N2A/H1N1
California
Perth
Brisbane
76