Question

Describe the ways in which communicable diseases are transmitted through various indirect methods.

Answer 1

Indirect method of transmission of communicable diseases are following :
(i) Contaminated food and water or drink:
Many intestinal diseases are spread by the intake of vegetables and fruits that are not washed properly or are washed with contaminated water. The germs on infected vegetables and fruits on reaching our alimentary canal, multiply and cause the disease.
(ii) Vectors :
Vectors are those organisms (e.g. house flies, mosquitoes, etc.) which carry germs from a source of infection but themselves do not get the infection. For example, mosquitoes while feeding on the blood of a malaria patient, gain the germs in their bodies, and get them transferred.
(iii) Droplet infection :
Many viral and bacterial diseases of the respiratory tract are transmitted through droplets. For example, the germs of tuberculosis pass into the air during sneezing or coughing of the patient. These fine droplets remain suspended in the air for quite some time.