What is a point source epidemic curve?

What is a point source epidemic curve?

In a point source outbreak, persons are exposed over a brief time to the same source, such as a single meal or an event. The number of cases rises rapidly to a peak and falls gradually. The majority of cases occur within one incubation period of the disease.

What is an example of a point source epidemic?

The graph above from a hepatitis outbreak is an example of a point source epidemic. The incubation period for hepatitis ranges from 15-50 days, with an average of about 28-30 days.

What are the three main sources of an epidemic?

Epidemics of infectious disease are generally caused by several factors including a change in the ecology of the host population (e.g., increased stress or increase in the density of a vector species), a genetic change in the pathogen reservoir or the introduction of an emerging pathogen to a host population (by …

What are the 4 things an epi curve can tell you?

What an Epi Curve Can Tell You

• The outbreak’s time trend, which is the distribution of cases over time.
• Outliers, that is, cases that stand apart from the overall pattern.
• General sense of the illness magnitude.
• Inferences about the outbreak’s mode of spread.
• The most likely period of exposure.

What are the uses of epidemic curve?

Epidemic curves are a useful epidemiological method in outbreak investigations and are used to; Determine the type of epidemic (common source, point source, propagated) Determine the difference between the maximum and minimum incubation period. Estimate the likely time of exposure.

What is the difference between common source epidemic and propagated epidemic?

common source outbreak: a type of epidemic outbreak where the affected individuals had an exposure to a common agent. propagated outbreak: a type of epidemic outbreak where the disease spreads person-to-person. Affected individuals may become independent reservoirs leading to further exposures.

What are some examples of pandemics?

Other examples of pandemics in recent history

• The 2009 swine flu pandemic: The flu strain that caused this outbreak, H1N1, was first identified in the U.S. in April 2009.
• The HIV/AIDS pandemic: The first cases of HIV, the virus that causes AIDS, appeared in 1981.

How do you make an epidemic curve?

An epidemic curve is easy to construct if you can count up how many people came down with disease each day during the course of the epidemic.

1. Enter Data for Cases in Rows. Enter the cases into the spreadsheet, listing the data for each case in a separate row.
2. Sort by Date.
3. Tally the Number of New Cases Each Day.

How do you read an epidemic curve?

Determining the Period of Exposure

1. Identify the peak of the outbreak, which is the time period then the largest number of cases occurred.
2. Count back from the peak, the average incubation period for disease.
3. Identify the earliest case in the outbreak and count back the minimum incubation period.

What is a propagated source?

This is a propagated (progressive source) epidemic in which one or more of the first wave of cases serves as a source of infection for subsequent cases and those subsequent cases, in turn, serve as sources for later cases.

What is the difference between pandemic epidemic endemic and outbreak?

A PANDEMIC is an epidemic that’s spread over multiple countries or continents. ENDEMIC is something that belongs to a particular people or country. AN OUTBREAK is a greater-than-anticipated increase in the number of endemic cases. It can also be a single case in a new area.

How many major pandemics have occurred?

Three worldwide (pandemic) outbreaks of influenza occurred in the 20th century: in 1918, 1957, and 1968. The latter 2 were in the era of modern virology and most thoroughly characterized. All 3 have been informally identified by their presumed sites of origin as Spanish, Asian, and Hong Kong influenza, respectively.

An epi curve with a sharp upward slope and a gradual downward slope typically describes a point source outbreak. A point source outbreak is a common source outbreak in which the exposure period is relatively brief and all cases occur within one incu- bation period. Figure 3 illustrates a point source epidemic curve.

What does an epidemic curve with a gradual downward slope indicate?

An epi curve with a sharp upward slope and a gradual downward slope typically describes a point source outbreak. A point source outbreak is a common source outbreak in which the exposure period is relatively brief and all cases occur within one incu- bation period. Figure 3 illustrates a point source epidemic curve.

What is a point source outbreak?

A point source outbreak is a common source outbreak in which the exposure period is relatively brief and all cases occur within one incu- bation period. Figure 3 illustrates a point source epidemic curve.

What is the difference between point source and propagated epidemics?

A point source epidemic occurs when lots of people are exposed simultaneously to a source of infection such as food or water [3] and the resultant cases develop within one incubation period of the disease. Propagated epidemics are caused by the transmission of an infectious agent from one person to another, e.g. whooping cough [4].