River Blindness Parasite Now Drug Resistant

Posted Jun 29, 2007 by Debra Myers

For the past 20 years, there have been efforts made to control the spread of onchocerciasis, or river blindness in African communities. Recently, it's been discovered that this parasite has become drug resistant, and may end up being a major scourge.
Marigo River  Mali  where river blindness was once rife.
Marigo River, Mali, where river blindness was once rife.
There seems to be reason for alarm, since it has been discovered that adult parasites are drug resistant, and are still able to reproduce and transmit the disease. The new findings appeared in the June 16th edition of "The Lancet", authored by Dr. Roger Prichard, James McGill Professor in the University’s Institute of Parasitology.
River blindness is the world's second leading cause of blindness after trachoma. The parasite, filarial nematode, is transmitted by a black simulium fly bite. It causes vision problems leading up to blindness, and can also cause pathological changes in the skin. The parasite can live within the human body for 10 to 15 years, and producing millions of tiny worms each year.
The parasitic worms breed in fast flowing waters and once "a black simulium fly becomes infected, the worm larvae spread to its saliva glands. When it bites a human, these pass into the skin. Here they develop into adults and form nodules under the skin. These adults then breed, producing thousands of larvae which spread throughout the whole body - including the eyes. This causes intense itching."
Microscopic view of the worms:
Treatment for this consists of a drug called Ivermectin, which is widely available. "Dr. Prichard and his colleagues studied 2,501 infected people from 20 communities in Ghana, West Africa. Of those communities, 19 had been receiving annual doses of ivermectin, the only widely available drug used to treat onchocerciasis.
Although ivermectin wiped out the microfilarial stage of the parasite in 99 per cent of those treated, four communities experienced significant repopulation and in two communities, the prevalence of the parasite had doubled between 2000 and 2005, the researchers found. Two McGill graduate students, Mike Y Osei-Atweneboana and Jeff K.L. Eng, conducted the bulk of the research in collaboration with research institutions and health authorities in Ghana."
Dr. Prichard has warned the various health organizations to be monitoring this, since there is every possibility that there could be a reemergence of this disease.
It's not bad enough that these people are battling starvation, other health problems and even war, but they have an unseen enemy that can attack without warning. Sadly, there are two major social problems because of this disease:
> children miss out on education because they are staying at home to act as full-time carers for older relatives who have become blind
> people flee areas where the level of infection has hit hard, leaving 'ghost villages' behind. Unfortunately these infected areas are the ones with the most fertile land, closest to the river.
Hopefully, now that they have this knowledge and know that this can be gotten under control again, and it will be one less worry that these people have.
Additional sources:
Sight Savers International