Human African Trypanosomiasis

Human trypanosomiasis (African sleeping sickness) is caused by intercellular hemoflagellated protozoa of the genus Trypanosoma and transmitted by Glossina sp (tsetse fly), the intermediate host.

It ranks 7th on the WHO TDR list and belongs to category 1 of the current Tropical Disease Classification.

• 60 million people in 36 countries are at risk.
• Annually, 300,000 to 500,000 cases
• Epidemic in 3 countries
• Highly endemic in 12 countries
• Endemic status is unknown in 13 countries including Nigeria.
• Restricted to tsetse fly belts of Africa.

There are 2 recognizable forms:

• • The West African form (The Gambian Trypanosomiasis)
• • The East African form (The Rhodesian trypanosomiasis.

In the true sense, Gambian is the form more associated with sleeping sickness.

Transmission is by glossina species (tsetse flies) male and female.

They are blood sucking flies found in

• Vegetations by rivers and lakes
• Gallery forest
• Vast stretches of wooden savannah.

Occupational disease of farmers, animal rearers, fishermen etc. who are exposed to the bites of tsetse fly in their ecological habitat, e.g. riverine forests.

T. Brucie gambiense causes chronic infection while T. Brucie rhodesiense causes acute infection.

For WASS, in the early phase they are:

• Fever
• Headache
• Joint pain

In the later phase when the CNS is involved,

• Meningoencephalitis
• Meningomyelitis
• Emanciation
• Mental and physical apathy
• Tremors of the tongue
• Speech impairment
• Nervousness
• Drowsness (sleeping sickness)
• Lethargy
• Coma and death

For EASS, acute and very virulent. Incubation period is 2-3weeks. It is characterized by

• Fever
• Adenitis
• Rash
• Edema
• Hepatomegaly
• Splenomegaly
It is very virulent and immediately fatal before detection and commencement of treatment.

• Xeno diagnosis
• Intra dermal tests
• Immunological tests including card agglutination methods (when antibody is present in the blood, there will be visible agglutination on the card).
• Winter bottom sign (Negrolethargy) i.e. enlarged posterior cervical lymph node.

Management of Trypanosomiasis is complex and requires careful evaluation with appropriate considerations (precautions) for the following:

• Concommitant infections of the liver and kidney with respect to the capabilities of the liver to tolerate suramin, pentamidine etc.
• The type and stage of the infection and the meticulous assessment of the CNS involvement.
• Blood-Brain barrier especially when the CNS is involved as in Gambian trypanosomiasis.
• Patient’s nutritional status because malnutrition might lead to death or worsen the disease.
• Drug of choice:
• Suramin (Bayer 205) = Antrypol
• Pentamidine (not active against T. B rhodesiense)
• Trypanrsamide
• Mel B (Arsolbal melarsoprol) = only drug used routinely for patients with CNS involvement.
• Furacin
• Exceptional propensity of Trypanosomes for rapid protein turn over and mutation. This can lead to development of resistance rapidly.