Human trypanosomiasis

Parasitic disease caused by trypanosomes

Human trypanosomiasis, also known as sleeping sickness, is a parasitic disease caused by protozoan parasites of the genus Trypanosoma. It is transmitted to humans by the bite of an infected tsetse fly (Glossina species), which is found only in sub-Saharan Africa. The disease is endemic in 36 countries in sub-Saharan Africa, putting millions of people at risk.

Types

There are two main forms of human trypanosomiasis:

• Trypanosoma brucei gambiense (T.b. gambiense) causes the chronic form of the disease, which is prevalent in West and Central Africa. This form accounts for over 98% of reported cases of sleeping sickness.
• Trypanosoma brucei rhodesiense (T.b. rhodesiense) causes the acute form of the disease, which is found in Eastern and Southern Africa.

Transmission

Tsetse fly, the vector of trypanosomiasis

The disease is transmitted through the bite of an infected tsetse fly. The fly becomes infected after feeding on an infected human or animal. The parasites multiply in the fly and are transmitted to another host when the fly bites again.

Symptoms

The symptoms of human trypanosomiasis vary depending on the stage of the disease:

First Stage

In the first stage, known as the hemolymphatic phase, symptoms include:

• Fever
• Headaches
• Joint pains
• Itching

Second Stage

In the second stage, known as the neurological phase, the parasites cross the blood-brain barrier and infect the central nervous system. Symptoms include:

• Confusion
• Sensory disturbances
• Poor coordination
• Sleep cycle disturbances, which give the disease its name "sleeping sickness"

Diagnosis

Diagnosis of human trypanosomiasis involves:

• Clinical assessment of symptoms
• Serological tests to detect antibodies
• Microscopic examination of blood, lymph node aspirates, or cerebrospinal fluid to identify the parasites

Treatment

Treatment depends on the stage of the disease:

• In the first stage, treatment involves the use of pentamidine for T.b. gambiense and suramin for T.b. rhodesiense.
• In the second stage, treatment involves the use of more toxic drugs such as melarsoprol or eflornithine.

Prevention

Preventive measures include:

• Reducing contact with tsetse flies by wearing protective clothing and using insect repellent
• Clearing vegetation around human settlements to reduce tsetse fly habitats
• Using insecticide-treated nets and screens

Epidemiology

Human trypanosomiasis is endemic in 36 countries in sub-Saharan Africa. The disease primarily affects rural populations who depend on agriculture, fishing, animal husbandry, or hunting.

Related pages

• Trypanosomiasis
• Tsetse fly
• Protozoan infections