Onchocerciasis
| Classification according to ICD-10 | |
|---|---|
| B73 | Onchocerciasis |
| ICD-10 online (WHO version 2019) | |
Onchocerciasis or onchocerciasis is a human disease found in tropical areas of Africa and America . The chronic disease is caused by filariae of the species Onchocerca volvulus from the group of roundworms and leads to blindness, the so-called river blindness , in about 10% of the sick .
Route of infection
Disease carriers onchocerciasis are black flies of the genus Simulium , such as S. damnosum and S. neavei in Africa and S. callidum and S. metallicum in Central America, further S. ochraceum in Central and South America. The blood-sucking black flies act as intermediate hosts , ingesting microfilariae from sick people . In the mosquitoes, worm larvae develop from the microfilariae, which they in turn infect humans when they suck their blood. After the worm larvae have been transmitted to humans, it takes more than ten months for sexually mature nematodes to develop from them. The roundworms, which have a lifespan of up to 17 years, store themselves as parasites in the connective tissue and create microfilariae. The adult male and female worms usually live in clusters of up to 5 cm in onchocercomas in the subcutaneous tissue, while the very small microfilariae flow through the connective tissue. However, microfilariae can also be found in the eyes, where they can cause visual impairment or even blindness.
The term river blindness can be derived from the occurrence of the disease, mostly in the vicinity of rivers. The reason for this is the fact that the black fly larvae grow up in such waters and in the adult stage feed on people in the vicinity.
therapy
A complete cure is possible through treatments with ivermectin , which kills the microfilariae, and suramin, which combats adult worms. Suramin is the active substance of the 1916 Oskar Dressel and Richard Kothe synthesized Germanin , the first cure for sleeping sickness and other by trypanosomes Diseases caused.
A new approach in the fight against onchocerciasis is the administration of an antibiotic ( doxycycline ). This is directed against the endosymbionts of the genus Wolbachia, which are essential for the roundworm . A six week treatment with doxycycline causes the sterilization of the female worms.
Combat
In the early 1970s there was a sharp increase in the number of cases of the disease in Africa, especially in Burkina Faso . In addition to the serious health consequences, an increasing economic problem developed, as many fertile river valleys were abandoned and this led to losses in food production and social problems. With the participation of the World Health Organization , the Onchocerciasis Control Program (OCP) has been carried out to combat control since 1974 , initially in the seven West African states of Benin, Burkina Faso, Ghana, Ivory Coast, Mali, Niger and Togo. Ten years later, Guinea, Guinea-Bissau, Senegal and Sierra Leone joined the program. For a long time no suitable drug was known. Onchocerciasis was treated with diethylcarbamazine , which had massive side effects, such as B. the Mazzotti reaction has. The core of the program was the large-scale control of the black fly larvae with insecticides or larvicides and the renewed colonization of the bank areas. From 1988 the treatment with the active ingredient ivermectin or the drug Mectizan® took place. The program was renamed the African Program for Onchocerciasis Control (APOC) in 1995 and expanded to include 24 states. By 2012 over 100 million people had been treated and 95% of the area of the affected regions was covered.
In 1992 a program to combat onchocerciasis was initiated on the American continent, where it was still found in 13 individual herds in six countries (Brazil, Colombia, Ecuador, Guatemala, Mexico, Venezuela) in 2011. This was so successful that the eradication of the disease was confirmed in several countries (Colombia 2013, Ecuador 2014, Mexico 2015). In September 2015, the program announced that onchocerciasis only occurs in a remote border area between Brazil and Venezuela.
In 2015, William C. Campbell and Satoshi Ōmura jointly received half of the Nobel Prize for Medicine for the discovery of the drug avermectin , which is effective against roundworms and is an essential part of the fight against onchocerciasis.
See also
literature
- A. Hoerauf, DW Büttner, O. Adjei, E. Pearlman: Onchocerciasis . In: BMJ , 2003 Jan 25, 326 (7382), pp. 207-210. Review. PMID 12543839
Individual evidence
- ↑ Doxycycline for chemotherapy of filariasis: elimination of Wolbachia, essential bacterial endosymbionts in worms .
- ↑ Ellen de Nesnera: River blindness battle: A success story. In: Africa Report. Jhg. 31 No. 1, January / February 1986, p. 31.
- ^ African Program for Onchocerciasis Control (APOC) . WHO. Retrieved October 7, 2015.
- ↑ Ken Gustavsen, Adrian Hopkins, Mauricio Sauerbrey: Onchocerciasis in the Americas: from arrival to (near) elimination. In: Parasites & Vectors. 4, 2011, p. 205, doi: 10.1186 / 1756-3305-4-205 .
- ↑ Onchocerciasis . World Health Organization. Retrieved October 3, 2015.
- ↑ Brazil and Venezuela border is the last place in the Americas with river blindness . Outbreak News Today. Retrieved October 3, 2015.
- ^ Onchocerciasis Elimination Program for the Americas (OEPA) . World Health Organization. Retrieved October 3, 2015.
- ↑ Jan Andersson, Hans Forssberg, Juleen R. Zierath: avermectin and artemisinin - Revolutionary Therapies against Parasitic Diseases . The Nobel Assembly at Karolinska Institutet. October 5, 2015. Retrieved October 5, 2015.
