Question

cite four reasons why an individual might not develop an infectious disease after exposure to a pathogen? discuss the four period or phases in the course of an infectious disease.

Answer 1

Reason why an individual might not develop infection after exposure to pathogen-

1. Vaccination- Vaccination is given to develop the antibody in the body for particular type of pathogen. In vaccine killed or weak strained of pathogen or solution that contain antigen from that pathogen is given. Our body has memory lymphocyte that get activated when next time this pathogen attack the body and kill them.

2. Immunity- When a pathogen enters in body our lymphocyte recognized and multiply in number to kill pathogen. This immunity is natural for asset of a person or he might have got from vaccination. A person with good immunity has greater chance of evading the impact of pathogen.

3. First defense of body- We call them non-specific barrier also. These include anatomical barrier like skin, hair in nose. Physiological barrier like mouth and nasal protected by saliva and nasal secretion, vaginal secretion is acidic.

4. Specific mechanism- When pathogen efficiently pass through the barrier of non-specific mechanism they encounter specific mechanism. This mechanism has two components cell mediated response and antibody –mediated response. In first one T cell directly destroy infected body cell and in second T and B both cell destroy pathogen or eliminate toxin secreted by them.

Four period of infection-

Incubation period- During this period pathogen begin multiply and increase its number. This period occur in acute disease after the entry of pathogen in body. This period vary from days to months and generally pathogen doesn’t show disease symptoms.

Prodormal period- It comes after incubation where pathogen still continue to multiply but host show sign or symptoms of illness like fever, pain, swelling because of the activation of immune system.

Period of illness- During this period sign and symptoms are clear and severe.

Decline phase- During this period number of pathogen particles begin to decrease along with sign and symptoms of disease also.