Tsetse << TSEHT see >> fly is an African fly known for spreading disease. It carries trypanosomes, the animal parasites that cause African sleeping sickness, a potentially fatal human disease, and nagana, a deadly disease of cattle and horses.
There are more than 20 species (kinds) of tsetse flies. Several of them attack people. The flies resemble typical house flies, but they grow larger and fold their wings flat over their backs so that the wings do not stick out at an angle as they do on house flies. The tsetse fly’s long proboscis (beak) pierces the body of its host. Most tsetse flies suck blood from mammals, but some kinds take blood from reptiles and birds. As they suck blood, they infect the host. A tsetse fly transmits both nagana and sleeping sickness by biting an infected animal or person, picking up the parasites, and infecting the next host it bites.
The flies usually cannot infect people until the parasites have lived in their bodies several days and have passed through the stomach to their salivary glands. Then the flies can transmit the parasites to anyone they bite. The parasites that infect animals develop in the fly’s proboscis or in the stomach and proboscis.
Tsetse flies breed slowly. The female fly produces only one egg at a time. The larva hatches from the egg and is nourished during the growing period inside the body of the parent. When the larva is full-grown, it is deposited on the ground. It then burrows into the soil before transforming into a pupa.
Tsetse flies bite during the day. They often live by lakeshores and riverbanks, making parts of Africa uninhabitable. In some regions, insecticide sprays and removal of vegetation control tsetse fly populations. Other control programs use special traps. Drugs that protect cattle from nagana are also used. But political unrest in Africa has hampered control efforts.
See also Brucellosis; Sleeping sickness; Trypanosome.
