when-does-a-disease-become-endemic

Context: A top official of the World Health Organization (WHO) recently said that like HIV, the novel coronavirus could become endemic and “may never go away”.

What is an endemic disease?

  • According to the US Centers for Disease Control and Prevention (CDC), a disease is endemic when its presence or usual prevalence in the population is constant. 
  • The dictionary of epidemiology defines an endemic disease as, “the constant presence of a disease or infectious agent within a given geographic area or population group; may also refer to the usual prevalence of a given disease within such an area or group.”
  • 1948 definition: An endemic area is one in which over a number of years, there is practically continuous presence of clinical cholera with annual seasonal exacerbation of incidence.
  • Examples of endemic: Chicken pox and malaria, where there are a predictable number of cases every year in certain parts of the world.
  • When the cases begin to rise, it is classified as an epidemic. If this epidemic has been recorded in several countries and areas, it is called a pandemic.

What happens when a disease becomes endemic?

  • When epidemics become endemic, they become “increasingly tolerated” and the responsibility of protecting against it shifts from the government to the individual. 
  • This means, rather than government agencies actively engaging in tracking and identifying cases, the individuals themselves will be responsible for managing risk from the disease and seeking care.
  • Further, the sociopolitical response to the disease may also change, with investment in the disease becoming institutionalised along with the disease-inducing behavioural changes in people. 
  • Once people become aware of the risks of infection, they will alter their behaviour and mitigate the consequences.
  • The epidemic diseases have higher mortality and morbidity than endemic disease, owing to lack of clinical experience and knowledge as well as innate  pathogenicity.

When does a disease become endemic?

  • One mathematical modelling published in the Journal of Epidemiology and Community Health states that if R0, which is the rate at which the virus is transmitted, is equal to 1, then the disease is endemic. 
  • When R0>1, it implies that the cases are increasing and that the disease will eventually become an epidemic. 
  • If R0<1>

RO- In epidemiology, the basic reproduction number (sometimes called basic reproductive ratio, or incorrectly basic reproductive rate, and denoted R0, pronounced R nought or R zero of an infection can be thought of as the expected number of cases directly generated by one case in a population where all individuals are susceptible to infection.

The definition describes the state where no other individuals are infected or immunized (naturally or through vaccination). 

 

Source: https://indianexpress.com/article/explained/coronavirus-endemic-disease-meaning-6411740/

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