Question

SECTION I Short Answers

I.                   Define the following: Infection, disease, virulence and pathogen

Answer 1

Infection = Infection is entry or invasion of any microbe inside the host. There are various microbes which can cause infection. The infection is caused by living entity only. Example of infectious agents are Bacteria, viruses, fungi. nematodes etc.

Infection may or may not result in disease depending upon the host's immune response.

Disease- Disease is a condition where the bodily functions can not be performed normally. It is an abnormality which affects the organism negatively. Diseases are classified or identified by different types of signs and symptoms. Disease can be both mental or physical. Disease is generally associated with pain, functional anomaly or behavioural abnormality.

For example- Tuberculosis, Cholera and cancer

Virulence- Virulence is the capacity of any microorganism to damage or infect the host's cells . Virulence decides that whether any microbe is pathogenic or not. virulence is related to several virulence factors. For example different factors or molecules which enable the microbe to adhere, invade the host's cell along with ability to evade the host's immune response,

Pathogen- Pathogen is the organism which can cause the disease. Most of the pathogens are microbes but there are several macroscopic pathogens as well like Ascaris. Pathogens posses the ability to overwhelm the host/s defense system and trigger the disease.

Pathogens can be of many types like Virus, fungi, Bacteria, Prion and Viroid etc.