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Pengendalian dan pemberantasan penyakit 5-6/2014. DISIAPKAN OLEH PROF. DR.DRH.PRATIWI, TS. MS DRH.ROSITAWATI, I. MP. OUTBREAK INVESTIGATION. Definition Outbreak investigation purposes The pattern of temporal, spatial and animals 10 steps outbreak investigation. What is an outbreak ?. - PowerPoint PPT Presentation
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Pengendalian dan pemberantasan penyakit5-6/2014
DISIAPKAN OLEH PROF. DR.DRH.PRATIWI, TS. MS
DRH.ROSITAWATI, I. MP
02/05/2012PTS-RST-PKH-5-6-2014 1
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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5
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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