Protozoan Diseases - AFRICAN TRYPANOSOMIASIS

(African Sleeping Sickness, Gambian Trypanosomiasis, Rhodesian Trypanosomiasis)

AGENT:

Trypanosoma brucei, T. gambiense, and T. rhodesiense.

RESERVOIR AND INCIDENCE

Many wild and domestic animals harbor infection. In Gambian trypanosomiasis, humans are the main reservoir and source of infection for the vector tsetse fly (Glossina palpalis, G. tachinoides, or G. fuscipes). In Rhodesian trypanosomiasis, animals, especially domestic cattle and pigs, play an important role as reservoirs.

TRANSMISSION:

The tsetse fly is infected when it bites during the parasitemic phases and the trypanosome develops in the vector, culminating in infection of its saliva. Transmission is by the tsetse fly bite. In humans, intrauterine infection has been recorded.

DISEASE IN ANIMALS:

Occasionally mild disease occurs in domestic animals with chronic nervous sequela in T. gambiense infection.

DISEASE IN HUMANS:

The trypanosomal chancre: This a local pruritic, painful inflammatory reaction with regional lymphadenopathy that appears about 48 hours after the tsetse bite and lasts 2-4 weeks.
The hemolymphatic stage: Usually absent or unnoticed in T. b. gambiense infections. Irregular fevers, headaches, joint pains, malaise, pruritus, papular skin rash, edemas. Patients may succumb to myocarditis before signs of central nervous system invasion appear.
The meningoencephalitic stage: Insomnia, motor and sensory disorders, abnormal reflexes, somnolence to coma. Trypanosomes and increased white cells and protein in cerebrospinal fluid.

DIAGNOSIS:

Definitive diagnosis requires identifying the organism in the bite lesion, blood, lymph node aspirate, or CSF. Serologic tests become positive after 12 days.

TREATMENT:

Hemolymphatic stage: Suramin, eflornithine or pentamidine.
Late disease: melarsoprol or eflornithine or tryparsamide plus suramin.

PREVENTION/CONTROL:

Wear long sleeves and trousers in endemic areas. Avoid wearing dark-colored clothing, and use mosquito nets while sleeping. Repellents do not work on tsetse flies. Pentamidine is used as a chemoprophylaxis against the Gambian type.