By Ebele Orakpo

Health, they say, is wealth, so a situation where, according to statistics, about 300,000 people in Africa have lost their sight due to river blindness (onchocerciasis), more than 37 million people are infected while about 140 million are at risk of infection becomes a cause of worry. One then begins to wonder how such economies will be wealthy. Blindness is unarguably one of the worst diseases on earth, more so when it could have been easily prevented.

In this chat with Vanguard Learning, Professor Joseph Ezigbo, a professor of parasitology, former lecturer at the University of Nigeria, Nsukka and Chairman/CEO of Falcon Petroleum Limited, speaks on his work on onchocerciasis and its management. Excerpts:

Prof Joseph Ezigbo

Onchocerciasis or river blindness is a parasitic disease transmitted by the bite of small black flies called simulium which breed in fast flowing waters. Nigeria is said to be the most endemic country in the world.

Said Prof. Ezigbo who worked on river blindness and a few other researches within the ambit of medical parasitology; “Although so much has been done by the World Health Organisation and others to eliminate the disease, there are still cases of river blindness in Nigeria. Onchocerciasis is caused by Onchocerca volvulus (worm) transmitted through the bite of simulium fly.”

Types of onchocerciasis: “We have two types of river blindness –Savannah and Rain forest. The Savannah is more insidious and causes blindness more than the rain forest type. The rain forest type is more prevalent but not as insidious as the Savannah type. The two types of river blindness are caused by different strains of the same parasite.”

The carrier:
“The simulium fly that transmits the onchocerca lives in fast flowing waters and wherever you find such fast flowing waters, particularly in the savannah region, you still find onchocerciasis but not as prevalent as it used to be. So many researches were set up in the early 70s/80s to try and eradicate simulium. The issue then was that to reduce the incidence of simulium breeding in fast-flowing waters, you have to dam the rivers to slow them down.

“Once the river slows down, the fly will not breed in it but you see, if you slow down the river, you breed snails which are intermediate hosts for schistosomiasis which is prevalent in the tropics so you are caught in-between two evils. But slowly, we have been able to handle two of them so we can eliminate the two.”

•Simulium, agent of
river blindness

According the Ezigbo, the symptoms of river blindness include severe itching, eye damage, skin nodules and discolouration. “The disease is being managed with Ivermectin, a drug that has been used to reduce the incidence and prevalence of onchocerciasis particularly in Nigeria.

“It also acts on onchodermatitis (lizard’s skin) because ordinarily, you find that the itching that occurs with microfilariae under the skin causes onchodermatitis. From my research, I found that there is a reduction in the incidence of onchodermatitis with the use of Ivermectin and then also if a patient is given a little dose initially, it reduces the chances of corneal opacity,” he said.

Economic implications: “Onchocerciasis has a lot of economic implications because where it is endemic, you find the blind leading the blind. These people become liabilities because they cannot fit effectively into the economy. A man who sits and scratches all the time cannot concentrate. A blind man cannot participate meaningfully in anything so it has a serious effect on the economy. It is debilitating, it reduces the ability of people to work and contribute their quota to the economic wellbeing of the nation,” he stated.