chronic disease pdf

Trypanosomiasis is differentiated into the African Trypanosomiasis and the American trypanosomiasis (Chigas’ Disease) which are prevalent in the respective regions bearing their names. It is a transmissible disease conveyed by bites of tse tse fly and hence a good knowledge of such a disease can equip one for adequate prevention

African Trypanosomiasis
The causative agents for the African Trypanosomiasis (sleeping sickness) are the Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. Both forms are transmitted by the bite of infected tsetse flies (Glossina species), which inhabit the open savannah of eastern Africa (T.b.rhodesiense) or riverine areas in western and central Africa (T.b.gambiense). Wild game mammals (hartebeest, lion, hyena) as well as cattle act as reservoirs of T.b.rhodesiense. Trypanosoma b.gambiense has been found mostly in domestic pigs, cattle, and dogs. Although, there is evidence that antelope may also carry the parasite. Many fly-man transmission are more common in west and central Africa. When the trypanosomes are ingested by tsetse fly they embark on a complicated cycle of development and multiplication, first in the fly’s gut and later in its salivary glands.

Morphology
Trypanosoma b.gambiense can be seen as spindle-shaped cells with an undulatory membrane and pointed flagella at the ends. The organisms are motile, 25-40 micrometer in length. Their cytoplasm is stained light-blue while the nucleus, blepharoplast and flagellum are stained red.

Pathogenesis and clinical manifestations
Trypanosomiasis is a transmissible disease and is covered by the bite of the tsetse flies. Infection with trypanosomes gives rise to African sleeping sickness which is characterized by fever, rash, headache, lymphadenopathy, Odema of the brain. T.b.rhodesiense is more virulent. Rhodesien form of trypanosomiasis develops within weeks to months. Gambian form develops within years. The disease becomes chronic and persists for months and even years. There are alternating periods of fever and apparent recovery, followed by depression and progressive lethargy. A slight number of parasites are present in the blood. The trypanosomes are present in the tissues, particularly in the muscles and in the cerebrospinal fluid. The patient dies frequently from the disease.

Laboratory diagnosis
It comprises of microscopic examination of blood and material obtained by puncture of the enlarged lymph nodes; examination of the cerebrospinal fluid (for the presence of trypanosomes).

Prophylaxis is ensured by a complex measures which include recognition and treatment of patients, protection of the population from the bites of tsetse flies (Glossina palpalis), the use of insect repellents, extermination of vector flies.

Trypanosoma Cruzi
This is the causative agent of the American trypanosomiasis (Chigas’ Disease). T. cruzi was discovered in 1909 by C. Chigas in Brazil. Children are the most susceptible to this disease. American trypanosomiasis is transmitted by bite of various bug species of the family Triatomidae. The natural reservoirs of the disease are wild animals- armadilloes, opossums, rodents, and monkeys.

Clinical manifestations
Children younger than one year of age suffer from the disease very frequently and die within a few days. In adults, the disease is accompanied with a rise of temperature, edema of the face, and enlargement of the thyroid gland lymph nodes, spleen and liver.

Laboratory diagnosis
This is made by examinations of patient’s blood; guinea pig inoculation with 5-10ml of patient’s blood. Prophylaxis is achieved by extermination of bugs (the vectors of the causative agent). Chemoprophylaxis with special preparation is carried out in endemic areas.