Skip to 0 minutes and 0 secondsIn this short video we will describe one of the basic principles of Epidemiology that concerns infection. It's worth remembering that some infectious agents are more transmissible than others. Now a sporadic infection describes a disease that occurs infrequently and irregularly within a population. On the other hand, an epidemic is used to describe a sudden increase in the number of cases of a disease to a level that is greater than the expected level in a given population in an area. An outbreak has a very similar definition to epidemic but it's used to describe an epidemic that is occurring in a more limited geographic area.
Skip to 0 minutes and 45 secondsClusters refer to an aggregation of cases of infection that seem to be grouped together in both time and place, and are again thought to be greater than the number expected, even if the expected number of cases might not be known. A Pandemic, on the other hand, is an epidemic that is spread over several countries, or continents, and is affecting a large number of people. Now, an epidemic can be the result of an increase in the amount or virulence of an infectious agent, or it may be that the infectious agent has moved to a new environment ,or it might be being transmitted more effectively, and this is allowing a wider population to become exposed to the agent.
Skip to 1 minute and 25 secondsFinally, we have an endemic infection. The term endemic is used to describe the amount of a particular disease that is usually present in a community. Now it's clear that the endemic level may not be the zero that we hope for, and without a suitable intervention, such as better infection control, or a policy of immunisation, the disease may continue to occur within the population in many ways. Endemic can be considered as the baseline level, or the expected level of an infectious disease.
Outbreaks and epidemics
Understanding the differences between an outbreak of an infection and a full-blown epidemic can be useful. Watch this short video to get to grips with some of the terminology that you may come across.
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