2nd August 2023

Trypanosomiasis

Two variants of this potentially fatal protozoal disease are important – African trypanosomiasis (also known as sleeping sickness) and American trypanosomiasis (Chagas disease).

African trypanosomiasis (sleeping sickness)

Two forms of African trypanosomiasis are significant – Trypanosoma gambiense (predominates in west and central Africa) and trypanosoma rhodesiense (predominates in east and south Africa), where the latter runs a more acute course, with systemic symptoms usually presenting within 3 weeks. They are both transmitted through the bite of the tsetse fly. Trypanosoma rhodesiense tends to be more acute, but both can present with:

• Chancre – painful, erythematous, inflammatory lesion at the site of the infective bite
• Fever
• Posterior cervical lymphadenopathy
• Neurological abnormalities (late stage) – sleep disorder, behavioural changes, headaches, meningoencephalitis
• Rare features – amenorrhoea, impotence, cardiomyopathy

Diagnosis is through blood and CSF serology and microscopy and first line treatment with IV pentamidine.

American trypanosomiasis (Chagas disease)

American trypanosomiasis is caused by Trypanosoma cruzi, which is predominantly endemic in Latin America. The main transmission route is vector-borne, through the triatomine bug, but it can also be transmitted through contaminated food, blood transfusions and vertically, from mother to baby. The acute phase is largely asymptomatic but can present with non-specific symptoms of malaise and fever. Rarely, the illness may present with a ‘chagoma’, an erythematous nodule at the site of infection, usually on the face or extremities. In very rare cases, acute infection can result in acute myocarditis.

Treatment, usually with benznidazole, in the acute phase is most effective in preventing chronic Chagas. Chronic Chagas is a major cause of morbidity in developing countries. It most commonly results in dilated cardiomyopathy, causing heart failure and arrhythmias, and rarely in megaoesophagus and megacolon, causing dysphagia and constipation, respectively.