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Human African trypanosomiasis, AKA "sleeping sickness", is a vector-borne parasitic disease. The disease is caused by infection with the protozoan parasite Trypanosoma brucei.
The disease takes two forms depending of the parasite involved.
Either Trypanosoma brucei gambiense (T.b. gambiense) which is the more common. Or Trypanosoma brucei rhodesiense (T.b. rhodesiense) which is a rare and rapid disease.
The Trypanosoma brucei parasite is a unicellular parasite that lives in the blood, lymphatic system, and interstitial spaces of organs.
It is transmitted to humans by Tsetse fly (Glossina genus) bites. These Testse flys acquire infection from humans or animals whom have the pathogenic parasites.
The fly is found in sub-Sahara Africa often in rural areas. However oddly in many rural where the Testse fly is found, Trypanosomiasis is not.
The disease is mostly transmitted through the bite of an infected tsetse fly although there are other ways in which people are infected:
- Mother-to-child infection: the trypanosome can cross the placenta and infect the fetus.
- Mechanical transmission through other blood-sucking insects is possible, however, it is difficult to assess its epidemiological impact.
- Accidental infections have occurred in laboratories due to pricks with contaminated needles.
Transmission of the parasite through sexual contact has been documented.
Disease must be diagnosed which should be made as early as possible to avoid progressing to the neurological stage (stage 2) of symptoms and treated with medical treatment.
The disease is diagnosed through the process of:
- First screening for the infection, involving serological tests and checking for clinical signs, particularly swollen cervical lymph nodes.
- Then testing to see if the parasite is present in blood fluids to diagnose the patient.
- Following with staging in order to determine the state of disease progression, this entails examining the cerebrospinal fluid obtained by lumbar puncture.
Hosts should be treated as soon as possible.
A person may be infected for months or even years without major signs or symptoms of the disease.
People with symptoms may experience:
-pain in the joints or muscles
-insomnia or sleepiness
-weight loss and weakness
-fever
-headache
-itching
-mental confusion
-personality change
-problems with coordination
-skin rash
-swollen lymph nodes
Treatment involves drugs to kill the parasites. Depending of the stage of the disease will effect the treatment used.
The earlier that the disease is identified, the better the prospect of a cure.
Patients must be re assets 24 months post treatment with blood fluid tests including cerebrospinal fluid obtained by lumbar puncture, as parasites may remain viable for long periods and reproduce the disease months after treatment.
In the first stage, the trypanosomes multiply in subcutaneous (under skin) tissues, blood and lymph. This is also called haemo-lymphatic stage. This stage contains much milder symptoms.
During the first stage the drugs associated are safer to administer than those for second stage.
Pentamidine: discovered in 1940, used for the treatment of the first stage of T.b. gambiense sleeping sickness. Despite non-negligible undesirable effects, it is in general well tolerated by patients.
Suramin: discovered in 1920, used for the treatment of the first stage of T.b. rhodesiense. It provokes certain undesirable effects, including urinary tract and allergic reactions.
In the second stage the parasites cross the blood-brain barrier to infect the central nervous system. This is known as the neurological or meningo-encephalic stage. Symptoms become much clearer.
Stage two treatment success depends on drugs that cross the blood-brain barrier to reach the parasite. Such drugs are toxic and complicated to administer.
Melarsoprol: Discovered in 1949, it is used for the treatment of both gambiense and rhodesiense infections.
Eflornithine: Less toxic than melarsoprol, was registered in 1990. It is only effective against T.b. gambiense. The regimen is complex and difficult to apply.
Nifurtimox: A combination treatment of nifurtimox and eflornithine was introduced in 2009.
Unfortunately there is no effective vaccine against the Human African Sleeping Sickness that currently exists to prevent the virus, however development of a vaccine is the subject of current research.
To best control this disease humans should stay away from the Testse fly as best as they can by wearing covering clothes, insect repellent and of course seeing a doctor to be treated as soon as symptoms arise.