Pengendalian dan pemberantasan penyakit5-6/2014

DISIAPKAN OLEH PROF. DR.DRH.PRATIWI, TS. MS

DRH.ROSITAWATI, I. MP

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OUTBREAK

INVESTIGATIO

N

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Definition Outbreak investigation purposes The pattern of temporal, spatial and animals

10 steps outbreak investigation

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Definitions

Occurrence of more cases of disease than expected : - in a given area - among a specific group of population- over a particular period of time

What is an outbreak ?

Outbreak Epidemiology- Study of a disease cluster or epidemic

in order to control or prevent further spread of the disease in the population.

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PENGENDALIAN BERDASARKAN PERWILAYAHAN (ZONING)

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DAERAH TERTULAR: daerah yang sudah dinyatakan ada kasus secara klinis, PA dan HP serta dikonfirmasi dgn hasil laboratorium

DAERAH TERANCAM: daerah yang berbatasan langsung dengan daerah tertular atau tidak memiliki batasan alam dengan daerah tertular

DAERAH BEBAS: daerah yang dinyatakan masih belum ada kasus secara klinis, PA dan HP atau memiliki batasan alam (propinsi, pulau)

SISTEM KEWASPADAAN DINI(EARLY WARNING SYSTEM)

SUBSISTEM KESIAGAAN DINI - PENGAMATAN DINI - PENANGGULANGAN DINI

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SISTEM KEWASPADAAN DINI(EARLY WARNING SYSTEM)

SUBSISTEM PERAMALAN WABAH - PREDIKSI KEJADIAN WABAH - TINDAKAN ANTISIPASI

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Outbreaks

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2 or more cases associated in time and place

E. coli 0157:H7 (Northwest) Cryptosporidium (Milwaukee) Norwalk virus (Cruise ships) Vibrio cholerae (South America) Listeria (New York, New Jersey, CT)

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What is infectious disease epidemiology?

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Epidemiology Deals with one population Risk case Identifies causes

Infectious disease epidemiology Two or more populations A case is a risk factor The cause often known

(www)02/05/2012

Agents

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Clostridium botulinum, C. perfringens Staphylococci, Salmonella, Shigella Campylobacter jejuni, E. coli 0157:H7 Vibrio parahaemolyticus Hepatitis A, Norwalk virus, Rotavirus Calicivirus, Listeria monocytogenes Cryptosporidium, Giardia, Bacillus

cereus Toxoplasma gondii, Cyclospora

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Food borne Diseases

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Infection◦ long incubation

period (days)◦ diarrhea, nausea,

vomiting, abdominal cramps. Fever often

◦ Salmonella, ◦ Hepatitis A◦ Listeria, Giardia◦ Vibrio,

Campylobacter◦ Norwalk virus

Intoxication◦ short incubation

period (minutes - hours)

◦ Vomiting, nausea, double vision, weakness, numbness, disorientation

◦ C. botulinum◦ Staph aureus◦ certain fish/ shellfish

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Natural Barriers to Infection

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Stomach acid pH 2 GI Tract immune system Normal intestinal flora Bile acids and digestive enzymes

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Increased Susceptibility

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Gastrectomy acid blockers for ulcers antacids, excessive consumption of water buffering capacity of food- milk, fatty foods antibiotic therapy very young, old immunocompromised stress, poor hygiene, underdeveloped areas

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Retrospective investigation

• Often the outbreak exists since days, weeks,months

• Many cases already occurred • Count on the memory of people• Many data already collected; use them or start all

over?

Never too late, but more difficult

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1) Establish the existence of an outbreak2) Confirm the diagnosis3) Define a case and count cases4) Perform descriptive epidemiology

(person, place and time)5) Determine who is at risk6) Develop hypotheses explaining exposure

& disease

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Steps in Investigating an Outbreak

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7) Evaluate hypotheses8) As necessary, reconsider/refine

hypotheses and execute additional studies– additional epidemiologic studies– other types of studies – laboratory,

environmental

9) Communicate findings – written report– presentations

10) Implement control and prevention measures

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Steps in Investigating an Outbreak

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Definition of outbreak• One case – for diseases of epidemic potential (e.g., measles, cholera)

• More than the expected number of cases – for endemic diseases

• Sometimes is quantitative threshold (e.g.meningococcal meningitis)

Importance of a good surveillance system for early warning

Confirm the Existence of an Outbreak

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• Determine whether there is an outbreak – an excess number of cases from what would be expected

• Establish a case definition – Non-ambiguous– Clinical / diagnostic verification– Person / place / time descriptions

• Identify and count cases of illness

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Verify the outbreak

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• Graph of the number of cases (y-axis) by their date or time of onset (x-axis)

• Interpreting an epidemic curve– Overall pattern: increase, peak,

decrease• Type of epidemic?• Incubation period?

– Outliers: • Unrelated? • Early or late exposure? • Index case? Secondary cases?

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Plot an Epidemic Curve

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Endemic vs. Epidemic

Endemic Epidemic

No.

of

Cas

es o

f a

Dis

ease

Time

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• Starts slowly• Time between the first case and the peak is comparable

to the incubation period. • Slow tail

Vector-borne Disease

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• This is the most common form of transmission in food-borne disease, in which a large population is exposed for a short period of time.

Point Source Transmission

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• In this case, there are several peaks, and the incubation period cannot be identified.

Continuing Common Source or Intermittent Exposure

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TIME, PLACE, PERSON May be possible to answer:

◦ Who is at risk?◦ What is source of infection?◦ What is mode of transmission?

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Descriptive Epidemiology

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• Distribution of cases by date of onset

• X axis: time Y axis: number of cases

• Shows:– Time limits / duration of the outbreak– Peak / incubation period– Form of curve: evolution of outbreak– Formulate hypothesis regarding source

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Descriptive Epidemiology - Time

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Cycle of Foodborne Disease Control and Prevention

Surveillance

Epidemiologic Investigation

AppliedResearch

Prevention Measures

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Talk with health workers Examine cases yourself ! Laboratory testing (e.g., malaria, cholera,

hemorrhagic fevers, etc.)

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Confirm the Diagnosis

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Epidemiologic Curve

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9

Date

Nu

mb

er

of

cases

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Control of present outbreak

Prevention of future similar outbreaks

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Recommend control measures

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Numerators◦ Describe cases in terms of

age, sex, other parameters : refugee / displaced / residents immunized , not immunized

Denominators◦ Distribution in the overall population (age, sex,...)

Compare rates to identify high risk groups

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Descriptive Epidemiology - Person

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Map cases: identify geographic places at risk

Determine where disease acquired: Home, work, travel, etc..

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Descriptive Epidemiology - Place

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Personal information• Age• Sex• Place of residence (address)• Other relevant “exposures”

– Refugees vs locals– Food source– Water source

• Ethnicity, religion, etc.

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Information to Collect on Cases

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Disease data Date of onset of symptoms Clinical symptoms and signs Immunized or not (measles, meningitis) Laboratory results (if any) Duration of disease, outcome (death,

cured,..) Treatment received

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Information to Collect on Cases

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Often obvious from descriptive epidemiology

Formulate idea about source of outbreak and mode of transmission

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Develop Hypotheses

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• Cross – sectional study?• Cohort study • Case – control study

– Identify cases– Select control group

• Possibly matched on age or sex or location• Community control, clinic control etc.

– Compare exposures among cases and controls– Calculate odds for various exposures

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Test Hypotheses

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Clarifies your own ideas / synthesis Presents data and conclusions to anyone

interested◦ Often epidemiologist don’t implement

interventions◦ Must communicate to those who will intervene

Advocacy: MOH, UN, other NGOs, donors Basis for future reference

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Write a Report

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Interventions include Prevention of further cases Control of transmission and source of

infection Improve case management, lower case-

fatality rate

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Implement - Take ACTION

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Terimakasih Selamat Belajar

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