Human trypanosomiasis

Human trypanosomiasis, also known as sleeping sickness (in Africa) and Chagas disease (in the Americas), is a group of diseases caused by the parasite Trypanosoma. These diseases affect millions of people worldwide and are transmitted by the bite of infected tsetse flies (Trypanosoma brucei species) in Africa, and through contact with the feces of infected triatomine bugs in the Americas (Trypanosoma cruzi).

Etiology

Human trypanosomiasis is caused by the protozoan parasites Trypanosoma brucei (African sleeping sickness) and Trypanosoma cruzi (Chagas disease). T. brucei has two subspecies that are pathogenic to humans: Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. T. brucei gambiense causes a chronic form of the disease, which is most common in West and Central Africa, while T. brucei rhodesiense causes an acute illness that is found in East and Southern Africa. T. cruzi is found in the Americas, from the southern United States to southern Argentina.

Transmission

The transmission of T. brucei species occurs through the bite of an infected tsetse fly, which is found only in sub-Saharan Africa. For T. cruzi, transmission can occur through several routes: the most common is through contact with the feces of an infected triatomine bug, also known as the "kissing bug". Other modes of transmission include congenital transmission (from a pregnant woman to her baby), blood transfusion, organ transplantation, and consumption of contaminated food or drink.

Symptoms

The symptoms of human trypanosomiasis vary depending on the stage of the infection. In the early stage, symptoms may include fever, headaches, joint pains, and itching. As the disease progresses to the neurological phase, more severe symptoms can appear, such as changes in behavior, confusion, sensory disturbances, and poor coordination. Without treatment, the disease can be fatal.

African Sleeping Sickness

In the case of T. brucei infection, the disease can progress from the hemolymphatic phase, characterized by fever, headaches, and joint pains, to the meningoencephalitic phase, where the parasite crosses the blood-brain barrier leading to neurological symptoms.

Chagas Disease

For T. cruzi infection, the acute phase may present mild symptoms or go unnoticed. However, the chronic phase can develop years to decades after the initial infection, potentially causing cardiac complications, digestive, and neurological alterations.

Diagnosis

Diagnosis of human trypanosomiasis involves identifying the parasite in body fluids such as blood, lymph node aspirates, or cerebrospinal fluid. For African sleeping sickness, the Card Agglutination Test for Trypanosomiasis (CATT) is commonly used for screening. Microscopic examination and PCR are also used for both diseases. The diagnosis of Chagas disease can additionally be confirmed through serological tests.

Treatment

The treatment for human trypanosomiasis depends on the species of Trypanosoma and the stage of the disease. For African sleeping sickness, drugs such as pentamidine, suramin, melarsoprol, and eflornithine are used, with the choice of drug depending on the subspecies and disease stage. For Chagas disease, the antiparasitic agents benznidazole and nifurtimox are the primary treatments.

Prevention

Prevention of human trypanosomiasis focuses on reducing contact with the disease vectors. For African sleeping sickness, this involves vector control strategies such as the use of insecticide-treated nets and clothing, and environmental management to reduce tsetse fly populations. For Chagas disease, efforts include improving housing and hygiene to eliminate triatomine bugs, screening blood donations, and testing pregnant women to prevent congenital transmission.

Epidemiology

Human trypanosomiasis remains a significant public health issue in sub-Saharan Africa and parts of the Americas. The World Health Organization (WHO) has targeted these diseases for elimination as public health problems, with ongoing efforts to reduce the number of new cases.