Thursday, July 21, 2011

Life Cycle Of T Brucei

Trypanosoma brucei, or T. Brucei is a species of parasite that lives within a mammal's bloodstream and is known to cause several neurologic conditions, most notably, African sleeping sickness. Sleeping sickness refers to a condition where the infected person experiences severe fatigue and eventually succumbs to coma and death.


History


As with most other parasites, T. Brucei requires several hosts in order to mature and reproduce. The primary host is mammalian, while the transmission vector is the Tsetse fly. Though Tsetse flies generally do not show signs of infection because they are unable to produce the substances needed to mature the parasitic larvae, they do show some signs of infection.


Life Cycle


The life cycle of T. Brucei is fairly simple. Tsetse flies feed on the blood of an infected mammal, where the immature parasites quickly evolve into the first stage of development, known as the procyclic stage. The procyclic larvae travel to the midgut of the tsetse fly and matures into a trypomastigote. The trypomastigote then travels to the salivary glands of the fly, where chemicals trigger the development process again, changing the trypomastigote into an epimastigote, where it goes through further cell division and enters into the final stage of development, the metacyclic stage. This is the stage where the parasite has become ready to infect a new host. The tsetse fly bites and transfers the metacyclic larvae into the new host. It is in the new primary host's bloodstream that T. Brucei completes its development into an adult and begins the cycle over again.








Defense mechanism


In order to survive in the host's bloodstream, T. Brucei has developed an advanced defense mechanism. The glycoproteins that encase the parasitechange about every 100 cell divisions. This occurs in order to stay one step ahead of the host's immune system, allowing for chronic infections to occur.


Symptoms of Infection








Early signs of infection include deep lesions where the parasite has damaged the capillaries in the skin, searching for larger blood vessels. Several days later, the host will experience lymphatic discomfort as the lymph nodes begin to drain from infection. The host will begin to have headaches, fever, and increased periods of fatigue. Several weeks to several years later, depending on the subspecies that is infecting the host, the parasite will begin to destroy organ tissues, most notably within the central nervous system.


Treatment


Treatments for T. Brucei do exist, however, since most infections occur in Third World countries, access to these life saving treatments is limited. Many people die from their infections without ever seeing a doctor or receiving any treatment at all.

Tags: signs infection, host bloodstream, host will, infections occur, Life Cycle, most notably