Onchocerciasis or River Blindness is a parasitic disease also called as Neglected Tropical Disease (NTD). River Blindness is the second infectious disease in the world to cause Blindness while trachoma being the first one. Besides visual impairment or Blindness, onchocerciasis also induces skin diseases as well as nodules beneath the skin or unbearable itching. River Blindness is the most common form of Blindness along the west and central Africa and also in some confined areas of Mexico, Venezuela, Columbia and Yemen. The disease is named as River Blindness because the black fly that transfers the infection, are found near streams and rivers and the infection leads to Blindness.
Symptoms of the disease in a person usually commences after 1 to 3 years of infection. River Blindness induces low vision and produces nodules on the skin and intense itching. The itching further leads to impairment of pigments and cause depigmentation on the skin and makes the skin more prone to cancer.
Photophobia, lacrimations are some symptoms observed after the infection of microfilariae.
In order to control the River Blindness or treat it, two main actions are set:-
The filarial parasite is a nematode to be responsible for onchocerciasis named Onchocerca volvulus. It is carried through repetitive bites via black flies of the genus Simulium. When these black flies bite the infected person, the microfilarias come inside the body of the fly. Further the disease is passed when these infected flies bite a normal humanbeing.
Every matured female microfilaria develops into millions of microscopic worms called as microfilariae. The microfilariae pass through the skin and after their demise, stimulate acute itching and coloration of the skin, lymphadenitis and elephantiasis of the genitalia. Severe visual impairment and Blindness occurs when the infection passes to the eye.
Secondary alteration of a degenerative type arises in the crystalline lens; anterioe synechiae are formed because of exudation of fibrin and leukocytes into the anterior part. The posterior part and optic nerve are also at times involved.
The consequence of all these actions is total Blindness with glaucoma and phthisis bulbi.
Hence, the distinct disease is normally mentioned as "River Blindness".
Onchocerciasis or River Blindness acquires three forms-
The progressive passage of the microfilariae to the vitreous humor and then the ciliary body results in visual impairment.