how the illness can be spread?
Organisms like virus, bacteria, fungi, protozoa and other micro-organisms which cause diseases are called infectious agents .Diseases where infectious agents are involved are known as infectious diseases. These organisms can spread in the community resulting in the spread of a disease.
Diseases can spread through the following means:
Water or food borne diseases
These diseases are transmitted when excretions from an infected person containing causal microorganisms get mixed with drinking water. Consumption of this contaminated water leads to the spread of diseases.
In addition, when food is prepared using this contaminated water, it can lead to food borne diseases. Some water and food borne diseases are cholera, typhoid, hepatitis A, etc.
Direct physical contact
Sexual act involves close contact between two people, which leads to the transfer of diseases such as syphilis, gonorrhoea, AIDS, etc. These diseases are known as sexually transmitted diseases . However, casual physical contact such as handshake, hugging, and kissing does not lead to the transfer of these diseases.
Blood to blood contact
This type of contact is established through blood transfusion or during pregnancy (between mother and baby) and through breast-feeding. AIDS is one disease that spreads through sexual contact as well as blood contact.
Animals or vector borne diseases
Organisms which do not cause diseases themselves, but spread infection by transferring disease-causing microorganisms from an infected person to others are known as vectors. For example: Female mosquitoes require highly nutritious blood to lay eggs, so they feed on warm-blooded animals. The female mosquito that bites an infected person can transfer the disease-causing microorganism from an infected person’s blood to a healthy person. Diseases like malaria, dengue, etc can spread through such means.