# 8.20D: Arthropods as Vectors

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Arthropods are capable of functioning as vectors by transmitting diseases.

##### Learning Objectives
• Demonstrate how arthropods act as disease vectors

## Key Points

• Arthropods will transmit diseases via their ability to function as hematophagous vectors which is characterized as their ability to feed on blood at some or all stages of their life cycles.
• Arthropod vectors include mosquitoes, fleas, sand flies, lice, fleas, ticks and mites.
• Arthropods transmit parasites either by injection into the blood stream of the host directly via their salivary glands, or by forcing parasites into a pool of blood which develops when chewing the skin.

## Key Terms

• vector: A carrier of a disease-causing agent.
• hematophagous: feeding on blood

Arthropods are capable of serving as vectors, indicating that they play a major role in disease transmission. Arthropods that serve as vectors include mosquitoes, fleas, sand flies, lice, ticks, and mites. These arthropods are responsible for the transmission of numerous diseases. These types of vectors are considered to be hematophagous. These arthropod vectors are characterized as feeding on blood at some or all stages of their life cycles. The arthropods feed on the blood which typically allows parasites to enter the bloodstream of the host.

The Anopheles mosquito serves as a vector for malaria, filariasis, and arboviruses as well (arthropod-borne-viruses). The Anopheles mosquito inserts its mouthpart under the skin and feeds on the hosts. As the mosquito is feeding on the host blood, the parasites which are carried by the mosquito, are typically located within its salivary glands. The mosquito is able to directly transfer the parasites into the blood stream of the host. Pool feeders, which include both the sand and black fly, responsible for Leishmaniasis and Onchocerciasis diseases, will chew the hosts skin. The chewing action produces a well which promotes the formation of a small pool of blood from which they feed. In the case of sand flies, responsible for Leishmaniasis, the parasites infect the host through the saliva. In the case of black flies, responsible for Onchocerciasis, the parasites are forced out of the insects head into the pool of blood. Tsetse flies are vectors of the human African trypanosomiasis, called “African sleeping sickness”. Additional examples of mosquitoes include the Aedes mosquito which is a vector for avian malaria, dengue fever, and yellow fever.

Fleas are another type of arthropod vector that transmit numerous diseases. The human flea, Pulex irritans, and the Oriental rat flea, Xenopsylla cheopis, are responsible for the transmission of the bubonic plague, murine typhus, and tapeworms.

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