Mazzotti reactions can be life-threatening, and are characterized by fever, urticaria, swollen and tender lymph nodes, tachycardia, hypotension, arthralgias, oedema, and abdominal pain that occur within seven days of treatment of microfilariasis.

The drug patch is placed on the skin, and if the patient is infected with O. volvulus microfilaria, localized pruritus and urticaria are seen at the application site.

The electroencephalogram is abnormal but cerebrospinal fluid (CSF) and magnetic resonance imaging (MRI) are normal or show non-specific changes.

[28] The Onchocerciasis Control Programme (OCP) launched in 1974, and at its peak, covered 30 million people in the following countries: Benin, Burkina Faso, Côte d'Ivoire, Ghana, Togo, Mali, and Niger.

The OCP utilized the following initiatives: the use of larvicide spraying into fast-flowing rivers to control black fly populations, and from 1988 onwards, the use of ivermectin to treat infected people as a core treatment therapy.

Recommended protection measures from the CDC include using insect repellents and wearing long sleeves and pants to eliminate exposed skin.

[33] The APOC ended in 2015 and aspects of its work has been taken over by the WHO Expanded Special Programme for the Elimination of Neglected Tropical Diseases (ESPEN).

As in the Americas, the objective of ESPEN has been to work with Government Health Ministries and partner non-governmental organizations, to eliminate the transmission of onchocerciasis.

This requires consistent annual treatment of 80% of the population in endemic areas for at least 10–12 years, the life span of the adult worm.

[35] On July 29, 2013, the Pan American Health Organization (PAHO) announced that after 16 years of efforts, Colombia had become the first country in the world to eliminate onchocerciasis.

Symptoms include urticaria, pruritus, fever, dermatitis, myalgia, swelling of the face and limbs, or postural hypotension.

Research on other antibiotics, such as rifampicin, has shown it to be effective in animal models at reducing Wolbachia both as an alternative and as an adjunct to doxycycline.

[44] Ivermectin is thought to irreversibly activate these channel receptors in the worm, eventually causing an inhibitory postsynaptic potential.

The chance of a future action potential occurring in synapses between neurons decreases and the nematodes experience flaccid paralysis followed by death.

[citation needed] Multiple exposures to Simulium blackflies raise the number of adult worms and microfilariae that are present in the host.

[61] According to a 2002 WHO report, onchocerciasis has not caused a single death, but its global burden is 987,000 disability adjusted life years (DALYs).

Infection reduces the host's immunity and resistance to other diseases, which results in an estimated reduction in life expectancy of 13 years.

[65] Onchocerca originated in Africa and was exported to the Americas by the slave trade, as part of the Columbian exchange that introduced other old-world diseases such as yellow fever into the New World.

They described a tropical worm infection with adult Onchocerca that included inflammation of the skin, especially the face ('erisipela de la costa'), and eyes.

[71] By the early 1920s, it was generally agreed that the filaria in Africa and Central America were morphologically indistinguishable and the same as that described by O'Neill 50 years earlier.

Scottish physician Donald Blacklock of the Liverpool School of Tropical Medicine confirmed this mode of transmission in studies in Sierra Leone.

Blacklock's experiments included the re-infection of Simulium flies exposed to portions of the skin of infected subjects on which nodules were present, which led to the elucidation of the life cycle of the Onchocerca parasite.

[73] Some of the patients reported seeing tangled threads or worms in their vision, which were microfilariae moving freely in the aqueous humor of the anterior chamber of the eye.

Hisette Isolated the microfilariae from an enucleated eye and described the typical chorioretinal scarring, later called the "Hissette-Ridley fundus" after another ophthalmologist, Harold Ridley, who also made extensive observations on onchocerciasis patients in northwest Ghana, publishing his findings in 1945.

The international scientific community was initially skeptical of Hisette's findings, but they were confirmed by the Harvard African Expedition of 1934, led by Richard P. Strong, an American tropical medicine physician.

[78] In 2015 William C. Campbell and Satoshi Ōmura were co-awarded half of that year's Nobel Prize in Physiology or Medicine for the discovery of the avermectin family of compounds, the forerunner of ivermectin.

[79] Uganda's government, working with the Carter Center river blindness program since 1996, switched strategies for the distribution of Mectizan.

In 2014, the program switched from village health teams to community distributors, primarily selecting women to assure that everyone in the circle of their family and friends received river blindness information and Mectizan.

[82] A study of 2501 people in Ghana showed the prevalence rate doubled between 2000 and 2005 despite treatment, suggesting the parasite is developing resistance to the drug.

[86] In 2017, WHO set up the Onchocerciasis Technical Advisory Subgroup (OTS) to further research and establish areas that require drug administration.