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.
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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:
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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;
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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
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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.