Beware: 5 Most Contagious Microbial Diseases

Microbial diseases are ailments caused in human beings as well as animals by the entry of any one of the four disease causing microbes - Bacteria, Fungi, Viruses and Protozoa. Here we list the 5 most contagious microbial diseases in humans:

1. Rota Virus Infection

Symptoms: Characterised by nausea and vomiting, watery diarrhoea and low-grade fever.

Rotavirus infection or gastroenteritis is caused by rotavirus. Out of the 8 species of this virus, Rotavirus A is the most common species responsible for more than 90% of the rotavirus infections in humans. This infection is highly contagious and the virus is transmitted by the faecal-oral route. It can spread from an infected person to other people from the time before diarrhoea develops until up to 10 days after symptoms have disappeared. More than 450,000 children worldwide under the age of five still die from rotavirus infection each year.

2. Measles

Symptoms: Characterised by fever, dry cough, runny nose, sore throat, inflamed eyes (conjunctivitis), Koplik’s spots along with the measles rash.


Measles is caused by the measles virus and is a highly contagious viral infection. It is an airborne disease and spreads easily through coughs, sneezes or contact with saliva or nasal secretions of the infected person. On an average, a person with measles sickens 12-18 unvaccinated people. It affects about 20 million people each year and resulted in 96,000 deaths in 2013.

3. Whooping Cough

Symptoms: Characterised by a runny nose, dry cough, sneezing and low-grade fever.


Whooping cough or Pertussis is a highly contagious airborne bacterial disease caused by the bacterium Bordetella pertussis. One may contract the disease through coughs and sneezes of an infected person. Around 16 million people worldwide are infected with the disease per year. The number of deaths caused by the disease dropped down from 138,000 in 1990 to 60,000 in 2013.

4. Mumps

Symptoms: Initial symptoms include low-grade fever, headache, muscle-pain and malaise, followed by painful swelling of one or both parotid glands.


Mumps or epidemic parotitis is a viral disease caused by the mumps virus. It is highly contagious and the virus spreads through contact with respiratory secretions of an infected person. It can be transmitted from one person to another through coughing sneezing or even laughing. A person infected with the virus can spread the disease to a healthy person from 3 days before the manifestation of symptoms to approximately 5 days after swelling of the salivary glands. The fatality rate of mumps is low and overall mortality is 1 in 10,000 cases.

5. Chicken Pox

Most Contagious Microbial DIseases

A chickenpox vaccine, also called the varicella vaccine should be administered to children once between the age of 12-15 months and then at 4-6 years. Source: Petras gagilas via

Symptoms: The early symptoms include nausea, loss of appetite, aching muscles and headache followed by the characteristic rash and oral sores.


The rash then forms small, itchy blisters which become cloudy after a day or two and eventually scab over.Chickenpox is a highly contagious disease caused by initial infection with varicella zoster virus (VZV). It is an airborne disease and spreads through coughs and sneezes of the infected person as well as through contact with blisters. In 2013, the disease resulted in 7,000 deaths, down from 8,900 in 1990. Death occurs in about 1 out of 60,000 cases.

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