What do you think is the deadliest animal for humans? You may think it is either lion or a shark. But mosquito is the deadliest organism for the human. Mosquito is killing human by spreading diseases such as Malaria, Dengue, Chikungunya. These diseases are called as vector borne diseases. In this topic we are going to explore about the vector borne diseases.
Vectors are living organisms which act as intermediate carriers of infectious agents. They transfer the infectious agents from one human to another human or from an animal.
Vectors can be an insect or an animal. Diseases such as  malaria, filaria, chikungunya, dengue are transmitted through insects, and the diseases transmitted by animals are bird flu and swine flu.
Pathogens stick to flies bodies as they sit on garbage, and these pathogens are then transferred to food when the flies sit on it again.
Examples of insect vectors:
Mosquitoes, lice, ticks and fleas.
Top left to right : Mosquito and lice; Bottom left to right - Ticks and fleas
Examples of animal vectors:
Monkeys, bats, pigs and birds
Top left to right: chimpanzee and bird; Bottom left to right - pig and bat
How it spreads the disease:
Vector such as mosquitoes, do not carry the pathogen from its birth. During a blood meal from an infected person, mosquito gets ingested with the pathogen, and when it bites an animal or healthy person, the pathogen will transmit into them. Thus, disease-producing microorganisms are transmitted through vectors.
A mosquito bite carrying an infectious agent
Vector-borne diseases:
Diseases transmitted from one human to another through vectors are called vector-borne diseases.
Comparison of airborne, waterborne and vector-borne diseases
Mode of transmission
Contaminated Air
Contaminated food and water
Insects and animals
Reservoir of infection
Mostly within the host
water, food and host
Vector and host
Infectious agents
Bacteria and Virus
Bacteria, virus
Protozoa, worms, virus
Humans and animals
Humans and animals
Humans, animals
Tuberculosis, whooping cough, diptheria,
common cold, mumps,
measles, chicken pox, influenza
Cholera, typhoid,
polio myelitis, acute diarrohea,
Hepatitis A
Malaria, dengue, chikungunya, filaria
In the following sections, we will study vector borne diseases such as,
  • Malaria
  • Chikungunya
  • Dengue
  • Filaria