Biology (NTSE/Olympiad)  

5. Human Disease

Means of Spread

Means of Spread
Infectious diseases are also called communicable diseases because they can spread from infected person to healthy person(s). The means of spread of these diseases are different for different pathogens.
Direct Transmission :
The disease causing microorganisms (pathogens) are transmitted from infected person to healthy person (s) directly in the following ways :

Physical contact with infected person : The pathogens of diseases like chicken pox, small pox, ring worm etc. are spread through physical contact with infected person or through articles of use.
Sexual Contact : Few infectious diseases such as syphilis, gonorrhoea (both caused by bacteria) and AIDS (caused by virus) are transmitted by sexual contact from one partner to the other.

Contact with soil : Many pathogens can enter the human body from soil through injuries (e.g., tetanus)
Animal bites : Communicable diseases can also spread through the animal bites. For example, rabies virus enters the human body by the bite of rabid dog or monkey to cause rabies.


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