Tsetse Fly :: essays research papers fc

Tsetse Fly African sleeping sickness is an infectious disease of tropical Africa. This infectious disease is caused by a protozoan organism that exists as a parasite in the blood of a number of vertebrate hosts. There are three variations of the disease that predominate in humans are transmitted by an insect vector: Two types of African sleeping sickness are caused by the following: Trypanosoma rhodesiense and T. gambiense, both transmitted by the bite of the tsetse fly. Trypanosome, which early symptoms include fever, headache, and chills, followed by anaemia and joint pains. Later, the disease attacks the central nervous system, causing drowsiness, lethargy, and, if left untreated, death. The cycle of this deadly disease starts out with the tsetse fly and usually end in death if untreated.   Ã‚  Ã‚  Ã‚  Ã‚  Tsetse flies are classified in the phylum Arthropoda, class insecta, order Diptera, family Trypanosoma. Tsetse flies are unusual insects. The medium to large brown flies are between six to 14mm long, excluding its proboscis (which is the trunk-like process of the head). The wings are folded and scissor-like while at rest and extend a short distance beyond the end of the abdomen. Other flies have their wings projecting side-ways unlike the tsetse fly, which has overlapping wings. Tsetse flies are confined to Africa. There are 390 different species and four are found in Zambia. They are in the same family as the house and horse flies, they feed extensively on blood be it that of humans or animals. They are parasites that live in the blood or tissue of humans and other vertebrates. Egg and larval stages develop within the female. 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 o f the parent. When the larva is full-grown, it is deposited on the ground, and it becomes a pupa. She gives birth every 9 to 10 days. Tsetse flies mate only once, but that mating provides enough sperm to fertilize the female throughout her 90 to 100 day lifespan. Female tsetses produce at most nine larvae and therefore have one of the lowest reproduction rates in the insect world. The single-celled trypanosomes that cause sleeping sickness spend their time cycling between humans and tsetse flies. They linger in the gut of the fly, absorbing amino acids and other molecules that the fly gets by biting mammals. After about ten days the trypanosomes move into the fly's salivary glands.