African sleeping sickness
African sleeping sickness, or African trypanosomiasis, is a parasitic disease caused by protozoa from the Trypanosoma genus. Transmitted primarily through bites from infected tsetse flies found in sub-Saharan Africa, the disease manifests in two forms: East African trypanosomiasis, caused by T. brucei rhodesiense, and West African trypanosomiasis, caused by T. brucei gambiense. Initial symptoms include a swollen sore at the bite site, fever, headaches, and fatigue, which may progress to severe neurological complications if left untreated, potentially leading to coma and death.
Diagnosis typically involves blood tests to identify the parasites, while treatment varies depending on the disease stage, with early detection enhancing cure rates. Preventive measures focus on avoiding tsetse fly bites through protective clothing and insect control strategies. Although the incidence of African sleeping sickness has decreased significantly due to improved healthcare and preventive measures, it remains a critical health concern in certain regions, particularly the Democratic Republic of Congo and Angola. Understanding this disease is essential for those traveling to affected areas or studying public health in sub-Saharan Africa.
African sleeping sickness
- ANATOMY OR SYSTEM AFFECTED: Brain, central nervous system, lymphatic system
- ALSO KNOWN AS: African trypanosomiasis, East African trypanosomiasis, West African trypanosomiasis
Definition
African sleeping sickness, also known as African trypanosomiasis, is a parasitic disease involving parasites belonging to the Trypanosoma genus of protozoa. The disease is usually transmitted by infected tsetse flies, which are found in sub-Saharan Africa. These flies live in vegetation by rivers, lakes, and forests. There are two types of African sleeping sickness: East African trypanosomiasis, which is caused by T. brucei rhodesiense, and West African trypanosomiasis, which is caused by T. brucei gambiense.
Causes
African sleeping sickness develops from an infection with protozoa. It is not transmitted from person to person through direct contact. In very rare cases, an infected pregnant woman can pass the disease to her fetus. An infected person donating blood can also pass it into a blood bank, risking infection for recipients of blood transfusions. When the protozoa reach the central nervous system, they can cause behavioral and neurological changes leading to coma and eventually death.
Risk Factors
A tsetse fly bite is the biggest risk for contracting African sleeping sickness. Therefore, for Westerners who travel to Africa, the natural habitat of these flies creates the opportunity for transmission. Occupation, age, living conditions, socioeconomic status, immune system deficiencies, and genetic factors are additional risk factors.
Symptoms
The initial symptom is a swollen, red sore, called a chancre, at the site of the tsetse fly bite. The disease then spreads into the bloodstream, which causes fever, headache, lymphedema, and sweating. As the parasitic infection reaches the nervous system, extreme tiredness results. As African sleeping sickness progresses, irreversible neurological damage occurs. Other symptoms that may occur include rash, tremors, painful joints, swollen lymph glands, and muscle weakness. If the infection enters the brain, seizures, irritability, and confusion are some of the symptoms that may develop. Untreated, the disease may progress over months or years, leading to coma and death.
Screening and Diagnosis
A thick blood smear can be used to diagnose the disease in its early stages. The blood needs to be fresh to allow for good visualization of the protozoa. Several sensitive techniques can be used to detect the parasite in the bloodstream; for example, the card agglutination trypanosomiasis test is used to screen for T. b. gambiense. Also, a spinal tap is performed, and a sample of fluid is taken from a swollen lymph gland. Several other diagnostic tests are available, including rapid diagnostic tests for antibodies, polymerase chain reaction tests, other serological tests, and microscopy techniques.
Treatment and Therapy
The treatment of African sleeping sickness is dependent upon the stage of the disease when first diagnosed. When the disease is recently acquired, less toxic drugs can be used to eradicate it. The earlier the disease is detected, the more probable the cure. When the disease is in the second stage of development, however, the medication must be able to cross the blood-brain barrier. Hospitalization is necessary, and periodic checkups are needed for two years. Late-stage disease may be untreatable. Other drugs targeting the disease at specific stages have also been developed. These include fexinidazole and nifurtimox-eflornithine combination therapy.
Prevention and Outcomes
The only way to prevent African sleeping sickness is to avoid insect bites, which involves insect control programs and wearing protective clothing.
Some research shows that injections of the medication pentamidine have favorable results in treating the early stages of T. b. gambiense infection, while suramin is more effective against T. b. rhodesiense. Eflornithine is used to treat second-stage T. b. gambiense disease and resistant disease.
African sleeping sickness has drastically declined in the twenty-first century as preventive efforts and medical care have become more widespread. While in 2009, cases of African sleeping sickness fell to just below 10,000, by 2023, only 675 cases were reported. It is important to note that underreporting may be an issue because African sleeping sickness occurs in underdeveloped areas. The Democratic Republic of Congo, Angola, and other countries in western and Central Africa report the highest number of African sleeping sickness cases.
Bibliography
"About Sleeping Sickness - Sleeping Sickness (African Trypanosomiasis)." CDC, 10 Sept. 2024, www.cdc.gov/sleeping-sickness/about/index.html. Accessed 2 Oct. 2024.
Bonomo, Robert A., and Robert A. Salata. "African Trypanosomiasis (Sleeping Sickness; Trypanosoma brucei Complex)." Nelson Textbook of Pediatrics. Edited by Richard E. Behrman, Robert M. Kliegman, and Hal B. Jenson. 20th ed., Philadelphia: Saunders, 2016.
Braakman, H. M., et al. "Lethal African Trypanosomiasis in Travelers: MRI and Neuropathology." Neurology, vol. 66, 2006, pp. 1094-1096.
"Human African Trypanosomiasis (Sleeping Sickness)." World Health Organization (WHO), www.who.int/data/gho/data/themes/topics/human-african-trypanosomiasis. Accessed 2 Oct. 2024.
Maudlin, I., P. H. Holmes, and M. A. Miles, editors. The Trypanosomiases. Cambridge: CABI, 2004.
"Trypanosomiasis, Human African (Sleeping Sickness)." World Health Organization (WHO), 2 May 2023, www.who.int/news-room/fact-sheets/detail/trypanosomiasis-human-african-(sleeping-sickness). Accessed 2 Oct. 2024.