T Cruzi Life Cycle
T. cruzi is a protozoan that causes an illness called Chagas disease and is related to the protozoans that cause African Sleeping Sickness. Blood-sucking insects called triatomine bugs transmit the disease. According to the Centers for Disease Control, Chagas disease occurs from the southern U.S. to Argentina.
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Human stages: Initial Infection
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An infected triatomine bug, also known as a kissing bug, will bite a host. The bug will release infected feces around the bite wound. Metacyclic trypomastigotes within the feces will enter the wound or through surrounding mucous membranes and invade cells around the site of infection.
Intracellular Amastigote Stage
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The trypomastigotes will then change into intracellular amastigotes and multiply by binary fission within the infected cells. These will eventually change into more trypomastigotes within the cell.
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Trypomastigote Stage
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The trypomastigotes will then break out of the infected cells and migrate into the bloodstream. Trypomastigotes will then infect other surrounding tissues, where they become amastigotes again. This is a continuous infective process.
Transmission to Insect Vector
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Kissing bugs acquire the parasites when they bite and feed on the blood of an infected host. The trypomastigotes within the blood will multiply in the bug's midgut then differentiate into infective metacyclic trypomastigotes in the insect's hindgut. The infected insect will then bite another host, passing on the metacyclic trypomastigotes, thereby starting the life cycle again.
Symptoms
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While the acute phase of the disease, which can last up to four months is often asymptomatic, it can involve fever, fatigue, body aches, loss of appetite, lymph gland, liver and spleen enlargement. The chronic illness that follows also may be asymptomatic, but can lead to heart arrythmias, myocarditis, congestive heart failure and cardiac arrest.
Diagnosis and Treatment
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Diagnosis can be determined through examination for trypomastigotes in a recently obtained sample of blood. Once a positive diagnosis has been confirmed, treatment should begin immediately. The drugs of choice for Chagas disease are benznidazole or nifurtimox.
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