What is meant by pathogen and pathogenic diseases?« Back to Questions List

Pathogen is a micro organism that causes a disease. The term began to be used since 1880s. Diseases caused by micro organisms in humans are known as pathogenic diseases. Pathogens include bacteria, virus and fungi. Fungi mainly cause diseases in crops and other plants. But it can cause diseases in humans too. These organisms cause a disease in a person when they enter the body. If the body fails to the infection caused by the organism, it leads to diseases.  Resultant diseases   by such microorganisms are infectious in character. Such diseases are contagious and can be passed from one person to another.


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Pathogens attack the body’s tissues directly or cause damage by secreting toxins. Bacterial infections can be easily treated through vaccination or antibiotics. The tendency of a pathogen to cause damage to a host’s fitness is called virulence. Pathogens get transmitted through different routes via air, direct or indirect contact, blood, water, insect bites or any other means.

Viruses are smallest micro organisms that normally cause common cold for which there is no effective medical treatment. Smallpox, influenza, colds, mumps, measles, chickenpox, rubella etc are some of the diseases caused by viral pathogens. Ebola, which is presently in news is also a viral pathogen. While bacteria release toxins, viruses damage our cells. Diseases caused by bacteria include food poisoning, cholera, typhoid and whooping cough.


Antibiotics are mainly used in treatment of bacterial pathogenic diseases. But they are ineffective against virus caused diseases. Anti bodies and anti toxins are specialized proteins which neutralize pathogens in many ways. White blood cells destroy the pathogens by producing antibodies which destroy the infectious micro organisms. The cells also produce anti-toxins to neutralize toxins created as a by-product. Researchers have now evidences that many of the pathogens have now acquired resistance to the antimicrobial agents used to treat these diseases. 



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