These are insects belonging to the phylum Arthropod (hence called arthropods). They transmit a variety of diseases. These ar­thropods are called vectors i.e. insects which transmit diseases.

Features of arthropods

1. They have a head, thorax (or cephalothorax) and an abdomen.

2. They have 3 to 5 pairs of legs.


3. One or two pairs of antennae may be present or absent.

4. They live in land or water.

Arthropod-borne diseases

The following are a few arthropods and the diseases transmit­ted by them:


1. Mosquito Malaria, filarial, encephalitis

2. Housefly Cholera, typhoid, diarrhea,dysentery and poliomyelitis

3. Sand fly Kala-agar, sand fly fever, oriental sore.

4. Rat flea Bubonic plague, epidemic typhus;


5. Itch mite Scabies.

Transmission of arthropod-borne diseases

Arthropods can transmit diseases by three mechanisms:

Direct contact: Arthropods are directly transferred from man to man through close contact e.g. scabies


Mechanical transmission: The disease agent is transmitted mechanically by the arthropod e.g. transmission of diarrhoea and dysentry by housefly.

Biological transmission: Here, the disease agent multiplies or undergoes developmental changes in the arthropod host.