What are the different means by which infectious diseases are spread?

Diseases can be spread through various means such as air, water, sexual contact, blood, and vector.

(i) Certain disease-causing micro-organisms are expelled in air by coughing, sneezing, talking, etc. These micro-organisms can travel through dust particles or water droplets in air to reach other people. For example, tuberculosis, pneumonia, etc. spread through air.

(ii) Sometimes causal micro-organisms get mixed with drinking water and spread water borne diseases. Cholera for example is water borne disease.

(iii) Sexual act between two people can lead to the transfer of diseases such as syphilis, gonorrhoea, AIDS, etc.

(iv) Certain diseases such as AIDS can spread via blood to blood contact during blood transfusion or pregnancy.

(v) Certain diseases spread by animals called vectors. For example mosquitoes spread malaria.