Investigation of Epidemic. Framework :. Introduction Definitions Objectives Components of outbreak investigation Information of outbreak Steps of an outbreak investigation. introduction.
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e.g:outbreak of HIV i.e. When there is a sharp increase in the number of HIV cases among sex workers in a city where the rate was low in the previous year.
e.g When there is high prevalence of HIV is found among the commercial sex workers in many cities of the country it is known as epidemic of HIV
Cluster: A group of cases in a certain place over a particular period without regard to whether the number of cases is more than expected.
1.Control & preventive measures
-diplomacy, - logical thinking,
-problem solving ability, -quantitative skills,
- epidemiological know -how and judgement.
4. Public, political, or legal concerns:
5. Program considerations:
e.g A member of the public may report 3 infants born with birth defects within a 1-month period in the same community
e.g outbreak of bloody diarrhoea E.coli 0157:H7 is isolated from a stool culture
e.g bloody diarrhoea or hemolytic uremia syndrome without microbiological confirmation
e.g. non-bloody diarrhoea without microbiological confirmation
-peripheral health personnel,
- personnel from other government departments,
-NGOs and key community representatives
Two types of outbreaks
1. Common source 2. Propagated source
1.Common source outbreak: This outbreak occurs when people gets the infection by exposure to the same source of infection. These are two types
Continuous common source: The epidemic curve shows an abrupt increase in number of cases but instead of having a peak decline within incubation period new cases persist for a longer time with a plateau shape instead of peak before decreasing.
Propagated source: This type of outbreak is caused by a transmission from one person to another person which requires direct contact such as touching, bitting, sexual contact
Slow increase in number of cases with progressive peaks approximately one incubation period apart. The span of 1st and last case will also last longer than several incubation period e.g HIV
DISTRIBUTION BY PLACE
Hypothesis can be generated by 2ways
1)First- Consider what you know about the disease itself?
-What is the agent’s usual reservoir?
-What vehicles are commonly implicated?
-What are the know risk factors?
2)Second- talk to few case patients by visiting to their homes to search for common exposures.
-Local staff community will provide information
Do necessary environmental or other studies to supplement the epidemiological study:
Although an analytical study might be able to confirm the hypothesis ,the investigator still needs to find environment or other evidence to support and explain the epidemiological evidence
Draw conclusions to explain the causes or determinants of outbreak based on clinical, laboratory, epidemiological& environmental evidence
Report and recommend appropriate control measures to concerned authorities at the local/national, and if appropriate at international levels: