River blindness is still here: Active cooperation of citizens imperative for eradication

Cycle of river blindness
Cycle of river blindness

The Ghana National Tropical Disease Programme of the Ghana Health Service will be conducting mass drug administration for onchocerciasis in late August through early September. With the exception of children less than five years old, pregnant mothers and the seriously ill, inhabitants in some endemic districts in the country will be treated.

Everybody should take part in the effort to kick out onchocerciasis, also known as river blindness.

Mass Drug Administration (MDA) involves giving treatment to every eligible member of a population or every person living in a defined geographical area. This means that all eligible people, regardless of whether or not they are infected, receive the treatment they need.

MDAs with ivermectin has been used to control onchocerciasis and since the last five years it is being used to eliminate the disease entirely.

This is the result of the recent scientific findings that has shown that regular mass ivermectin administration to all the eligible population will eliminate onchocerciasis. Treating all eligible people in a population regularly with ivermectin ensures elimination of infection from those infected and protects uninfected from having an infection.

Onchocerciasis is an infection caused by the parasitic worm Onchocerca volvulus, spread by the bite of an infected blackfly also known scientifically as Simulium. It is also called river blindness because the blackfly that transmits the infection breeds in rapidly flowing rivers and streams and bites people living in settlements near such rivers and streams, mostly remote rural villages, who become blind from the infection resulting from the bites.

Persons with heavy infections as a result of repeated bites by infected blackflies will usually have one or more of three conditions: itching which can be unrelenting, unsightly skin disease, nodules under the skin or eye disease which result in severe visual impairment and blindness. Onchocerciasis is also called Robles disease, particularly in Latin America where blindness caused by the disease was first recognized by a Guatemalan ophthalmologist or eye specialist called Dr. Robles after whom the disease was named.

The Global Burden of Disease Study estimated that in 2017 there were at least 20.9 million people infected worldwide, of which 14.6 million had skin disease and 1.15 million had vision loss. More than 99% of infected persons live in Africa.

Onchocerciasis is the second leading infectious cause of blindness and can cause debilitating and disfiguring skin disease. However, the worldwide burden of onchocerciasis has been immensely reduced as a result of very successful disease control programs led by the World Health Organization (WHO).

These programs were based on the control of the blackfly population and/or mass administration to affected communities of an oral drug called ivermectin (Mectizan™) that is donated by Merck & Co., Inc. As a result of these programs, millions of people are no longer at risk of debilitating itching, disfigurement, and blindness caused by onchocerciasis. Unfortunately, a few people refuse to take the medicine during mass treatment exercises that is usually organised twice in the year by the Ghana Neglected Tropical Disease Programme of the Ghana Health Services. This approach known as Mass Drug Administration (MDA) provides a single dose medication to all eligible individuals in the affected communities twice a year. Implemented over several years, MDA can significantly control the burden of onchocerciasis and eliminate onchocerciasis altogether.

The control of onchocerciasis in Ghana started in 1974 under the auspices of the Onchocerciasis Control Programme in West Africa (OCP) which ended in 2002. The OCP employed a combination of approaches including vector control, mobile community ivermectin treatment, and community-directed treatment with ivermectin (CDTI). From 1997, CDTI became the main control strategy employed by the Ghana OCP (GOCP). Currently, 137 districts remain endemic for onchocerciasis in Ghana and the Ashanti region has the highest number of endemic districts.

The control of onchocerciasis in Ghana has been very successful, with an average high infection level of 69.13% in 1975 decreasing significantly to a very low level of 0.72% in 2015. Between 1997 and 2016, the treatment coverage which is the effectiveness of the MDA increased from 58.50 to 83.80% of the total population who need treatment, with nearly 100 million ivermectin tablets distributed.

Onchocerciasis spreads by the bite of an infectious blackfly. The female blackfly bites a person to suck blood it needs for its propagation and thereby sucks microscopic worm larvae (called microfilariae) which dwell in the infected person’s skin. The larvae develop over approximately one week in the fly to a stage that is infectious to humans. An infectious blackfly, during its next blood meal, instills the larvae in the skin of the person.

The microscopic larvae develop in a nodule under the skin into an adult worm that start producing baby worms or microscopic worm which cause the oncho disease in human.

Those most at risk of onchocerciasis are people who live or work near rapidly flowing streams or rivers where there are Simulium blackfly breeding sites and the concentration of blackflies which are out to bite man to suck blood they need for their own propagation

MDA is a recommended strategy of the World Health Organization to control or eliminate several neglected tropical diseases including onchocerciasis.

High-coverage MDA in endemic areas aims to prevent and alleviate symptoms and morbidity on the one hand and can reduce transmission on the other, together improving the health of the people living in Ghana. All and sundry need to support MDAs to ensure that onchocerciasis is eliminated from Ghana.

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