Sanyam Jain, Academic Content Writer
Agents of infectious diseases
Infectious diseases are caused by pathogens that readily spread from infected ones to healthy ones found in a variety of categories-
Malaria (by Plasmodium)
Kala-azar (by Leishmania)
Sleeping sickness (by Trypanosoma)
Importance of category wise study of pathogens– treatment of diseases since similar drugs work against pathogens of the same category.
Pathogens inside the host–
Viruses live within the host cells and multiply rapidly.
Fungi & bacteria rarely live inside the cells and also multiply rapidly.
Worms multiply very slowly in comparison.
Drugs that act against bacteria
Block important biochemical pathways
e.g. Penicillin inhibit cell wall synthesis
Do not work for viruses
2. Means of spread of infectious diseases
Infectious diseases are caused by pathogens that readily spread from infected ones to healthy ones thus ‘communicated’. and so are communicable diseases.
Various modes of infection transmission–
Droplets, containing the pathogen, are released into the air through the cough or sneeze of an infected person.
When inhaled these cause infection in healthy people.
Examples: common cold, coronavirus disease (COVID-19), pneumonia and tuberculosis
Excreta from an infected person is mixed with drinking water.
Drinking such water causes infection in healthy people.
Examples: infectious gut diseases such as cholera
Sexually transmitted diseases (STDs)-
Examples: syphilis, AIDS
not spread by casual physical contact (handshake or hugs)
Animals that carry infectious agents from an infected person to another potential host.
mosquitoes- commonest vectors
females feed on highly nutritious blood meal of warm-blooded animals to be able to lay eggs