​Infectious Diseases and Microbiology - Onchocerciasis/ River Blindness (Onchocerca volvulus )

​Infectious Diseases and Microbiology - Onchocerciasis/ River Blindness (Onchocerca volvulus ) 
Onchocerciasis, often known as River Blindness, is a parasitic disease.
 Onchocerca volvulus is a parasitic roundworm belonging to the nematode family.
Transmitted by the intermediary of an arthropod vector.
 The Simulium black fly, which reproduces in swiftly moving streams and rivers, serves as the carrier of the disease.

Geographical regions where a certain disease is regularly seen include equatorial Africa and Central and South America.
The clinical causative agent of river blindness. The symptoms encompass a skin rash, itching, reduced elasticity in the subcutaneous tissue (resulting in the formation of enormous skin folds), and varying degrees of visual impairment, ranging from partial to complete blindness.

Upon entering the bite wound, the larvae proceed to travel towards the subcutaneous tissue, where they undergo development and transform into adults within fibrous nodules located beneath the skin. Once the worms reach maturity, they create microfilariae that travel through the subcutaneous tissue and skin. These microfilariae can be consumed by biting black flies, which helps to spread the infection.
The pathogenesis occurs due to an exaggerated immune response to the antigens of the parasite and the inflammation caused by the movement of the larvae. Microfilariae in ocular structures cause photophobia and inflammation in several parts of the eye, including the cornea, iris, ciliary body, retina, choroids, and optic nerve. Untreated illness can lead to blindness.

Microfilariae are observable in skin biopsies and can also be seen through slit-lamp examination of the anterior chamber of an affected eye.
The treatment consists of surgically extracting mature cutaneous nodules along with the administration of ivermectin (to eliminate microfilariae). Prevention encompasses the implementation of infection control strategies. Administering prophylactic ivermectin treatment in places where a disease is prevalent can decrease the number of microfilariae present.

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