Chapter : 5. Human Disease
Indirect Transmission
Indirect Transmission :
It involves spread of pathogens of some diseases through some intermediate agents. Indirect transmission occurs in the following ways :
Through air : Infectious microbes that cause common cold, tuberculosis, pneumonia etc. can spread through air from infected person.
Through contaminated food/water : Many infectious diseases can also spread through intake of contaminated food/water. For instance, cholera-causing microbes enter new host through the water they drink and cause disease in them.
Through vectors : Many animals living with us carry the infecting agents from an infected person to other potential host. These animals act as intermediate and are termed vectors. The vectors are, therefore the carriers of the disease-causing pathogens. The most common vectors are the insects.
Houseflies carry the causative organisms of cholera, typhoid, dysentry and tuberculosis on the legs and mouth parts from faeces and sputum to the food and drinks. The latter, if taken, cause infection in others.:
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