Onchocerciasis is a parasitic ailment caused by Onchocerca volvulus, a type of filarial nematode. It is widely known as River Blindness (got its name from the disease’s prime symptom presented as blindness), however the nematode itself does not cause the blindness but its endosymbiont, the Wolbachia pipientis. Onchocerciasis has been recorded as the second leading cause of blindness among infectious diseases. The parasite is transmitted to humans through a bite from a female black fly of genus Simulium. Specifically, these fly specie attacks during daytime and lounge along riverbanks. Incidence of this disease has been greater in areas proximate to rivers and declines in communities beyond these areas. It has been documented that this disease has been endemic in the Americas and in some parts of Africa.
Acquiring this disease necessitates prolonged exposure to the infected fly bites. If the parasite has successfully invaded the system, the disease then starts to manifest itself. Symptoms of Onchocerciasis involve both the skin and the eyes. Such clinical presentations are the following:
- Blindness (visual loss, eye lesions)
- Skin swelling
- Skin nodules
- Skin inflammation
- Skin itching
To identify and confirm the presence of Onchocerciasis, the following examinations and laboratories are to be conducted:
- Skin biopsy (determine presence of microfilariae)
- Histologic Tests (skin nodules and eye lesions)
- Serologic Examinations (verifies infection)
Up until today, Onchocerciasis has no vaccine or prophylaxis medication available in the market. It is however recommended to practice protective precautions and avoidance of these vectors. If one could avoid habitats of these fly specie, then the better. River – oriented activities should be avoided or minimized on areas where Onchocerciasis is endemic. One should use clothing that could protect their skin, the use of long pants and long sleeved shirts can be very helpful. Putting up screened rooms (including doors and windows) can prevent flies from coming in the house.
The drug of choice for Onchocerciasis is Ivermectin (Mectizan). Two doses are given to patients; each dose is given six months apart. This treatment is repeated every three years. Ivermectin specifically, if not destroy, paralyses the filariae which is responsible for the skin – related symptoms. To target the Wolbachia (the bacteria known to cause eye lesions, visual loss and blindness), an antibiotic known as Doxycycline is indicated. This is taken once daily for a period lasting up to six weeks.