After the recent Coronavirus outbreak also named as COVID -19 many people came across medical terms like an epidemic, endemic, and pandemic. Let’s try to understand the differences between these terms in simple language. These terms are used for the classification of diseases and also for disease control and prevention for the benefit of public health.
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The term endemic means there is a constant presence and/or usual prevalence of the disease or infectious disease in a population within a geographical region.
For example, Malaria is endemic to some areas of Africa and India. This means Malaria always present in a certain population or region. Another example is Chickenpox. Chickenpox affects young school children in the United Kingdom at a predictable rate and time. So endemic disease is the characteristic of a particular population, environment, or region that outbreaks at a predictable rate and interval.
The term Epidemic means there is a sudden spread of disease that affects a large number of people in a particular population in a short time of period. So the epidemic term is used for the outbreak of disease to a particular geographical area and affects a high proportion of the population in a short period.
It is not necessary that an epidemic disease is always contagious or spread from person to person. The epidemic term has been applied to West Nile fever which is a mosquito-borne disease and the obesity epidemic and also many other diseases by the World Health Organization.
Which factor triggers an epidemic :
Increase in virulence, introduction to news strains, or changes in host susceptibility of the infectious agents, these are some changes in infectious agents that may trigger an epidemic.
The pandemic term refers to an epidemic that has spread across countries and continents, which means spread over several countries or the worldwide spread of an epidemic.
Epidemic vs Pandemic:
Let’s understand this by the example of new Coronavirus or COVID 19. Centre for the novel coronavirus disease also named the COVID-19 is in Wuhan city of China. There was a sudden outbreak of COVID-19 in some areas of Wuhan city and in a short period of time, it has spread to many people. So it is said that COVID-19 is an epidemic in Wuhan city of China.
But in a short period of 1-3 months COVID-19 has spread to different countries and later on affecting most countries of the world. So WHO declared COVID-19 as a pandemic. When COVID-19 will be controlled WHO may withdraw the label of the pandemic from COVID-19. In the past HIV was also declared as a pandemic. Later on, the WHO declared it as ‘Global epidemic’.
In history, there were many pandemic diseases that affected many peoples, and some diseases also taken the lives of millions. Pandemic history can also be traced from ancient times. Here are some notable pandemic outbreaks in history.
Plague: is caused by the bacterium known as Yersinia pestis which spread through the bite of rodents like rat or handling the animals which are infected with the plague bacterium. Black Death also known as Plague was the worst pandemic history that killed nearly 75 to 200 million people worldwide during outbreak in 1331 to 1353.
Cholera: Cholera pandemic occurred many times but first it spread in India from 1817-1824. It began in Bengal and by 1920 spread across the whole of India killing around 10000 British troops and countless Indians.
Influenza: It was first narrated by Hippocrates also known as ‘Father Of Medicine’, and there are many pandemic outbreaks in history. But worst was in 1918-1919 also known as ‘Spanish Flu’. The outbreak started in 1918 and within six to seven months spread to most of the continents. And 50 million people were dead within six months.
Smallpox: Caused by Variola virus, outbreak traced in 18thcentury. During 1950 around 50 million cases reported worldwide. In December 1979, WHO declared eradication of Smallpox, due to successful vaccination.
Measles: Caused by the measles virus, is highly contagious and was prevalent throughout the world. In the last 150 years, measles has taken the lives of around 200 million people. Vaccine for the measles was first introduced in the year 1963.
Tuberculosis: caused by Mycobacterium tuberculosis, and is still one of the major health problems in developing countries.
Malaria, Yellow fever, HIV, and many others are also some pandemic diseases that can be traced from history. Malaria occurs in tropical and subtropical areas and is still a common epidemic in many areas.
COVID-19: In recent days you all aware of the new Novel coronavirus pandemic affecting the whole world started from Wuhan city of China nearly in December 2019.
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