Microbes And Disease

Microbes or microorganisms are small, unicellular organisms which cannot be seen with our naked eyes. Some microbes are useful in our day to day life while some are harmful to our health. The microorganisms which are harmful to us are called pathogens.

Various kinds of pathogens include bacteria, viruses, protozoa, and a few variations of worms as well. Once they invade the host cell, they disrupt or damage the normal cellular activities. This leads to diseases on a larger scale.

Also Read: Diseases

Disease causing Microbes

Disease-causing Microbes

Diseases Caused By Microorganisms

There are several diseases caused by microorganisms such as viral diseases caused by viruses, bacterial diseases caused by bacteria, malaria caused by protozoans, etc.

  • Viral diseases, as the name sounds it is caused by the virus. These include both acute and infectious diseases like the common cold, to chronic disease like AIDS.  Apart from these acute diseases, it is also responsible for mumps, polio, rabies etc.
  • Diseases caused by bacteria include diphtheria, typhoid, cholera etc.
  • Malaria and sleeping sickness are diseases caused by protozoa.
  • Worms like roundworms, tapeworms could cause diseases like Ascariasis and Taeniasis respectively.

The microorganisms cause diseases in the following ways:

  • They reach their target site in the body
  • Multiply rapidly
  • Attach the target site to be infected
  • Avoid and survive an attack by the immune system of the host
  • Obtain nutrients from the host

Following is the list of microorganisms and infectious diseases caused by them:

Diseases Microorganisms
Cold Rhinovirus
German Measles Rubella
Chickenpox Varicella-zoster
Whooping cough Bardotella pertussis
Bubonic plague Yersinia pestis
Ringworm Trichophyton rubrum
Tuberculosis Mycobacterium tuberculosis
Malaria Plasmodium falciparum
Athlete’s foot Trichophyton mentagrophytes

The source and means of transfer of these infections are quite different. The sources through which the bacteria spread diseases is different from that of viruses. The main source of bacterial infection is contaminated food and water while viral diseases spread mainly through the air. Hence, bacterial and viral diseases are usually communicable. Other means of transfer of pathogens include direct physical contact i.e. blood transfusion, breastfeeding, sexual contact etc.

Also Refer: Communicable Non Communicable Diseases 

Microbes enter our body through different sites:

  • Respiratory tract
  • Urogenital tract
  • Gastrointestinal tract
  • Skin surface

Certain pathogenic diseases are organ or tissue-specific. For example, Tuberculosis affects the lungs of the individuals while Jaundice causing viruses targets the liver.


There is the quote, ‘prevention is better than cure’. Drugs like antibiotics or antibacterials are used to destroy or slow down the growth of bacteria. These antibiotics, however, are not effective for viral infections. The depth or severity of infection depends on the amount and rate at which microbes spread.

Also Read: Principles of Prevention

For more information on different microorganisms and diseases caused by microorganisms, keep visiting BYJU’S website or download BYJU’S app for further reference.

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