Disease Outbreak

Disease Outbreak a sudden rise in the number of cases of a disease over normal expectancy in a geographical location or season, ie, above the baseline or endemic level of the disease. It may involve a small and localized community or impact thousands of people across continents. The occurrences of disease cases depend on the disease-causing agent and the size, existing, and previous exposure to the agents. Several outbreak patterns can help identify the transmission method or source and predict the future infection rate.

Outbreaks can start from (i) a common source, such as a contaminated water supply can infect all victims, in a point-source outbreak, brief exposure makes everyone ill within one incubation period, and case patients may have a wide range of exposure and incubation or (ii) a propagated outbreak, cases with more than one incubation period, results from transmission via direct person-to-person contact, as with syphilis, or may also be vehicle-borne (eg, by sharing needles in hepatitis B or HIV) or vector-borne (eg, by mosquitoes in yellow fever).

Occurrence patterns of disease outbreaks are either Endemic – a communicable disease, ie, influenza, pneumonia, etc, that refers to the natural prevalence of the disease or infectious agent in a population within a geographic location, a particular place, or, among a specific community; Epidemic – when this disease affected a considerably huge number of people at the same time than is usual at that time among that population and may spread through one or several communities. [Mamun Rashid Chowdhury]