Onchocerciasis or “river blindness” is a disease caused by a parasite and the first cause of blindness in the world despite the existence of antibiotic treatment. British researchers have just succeeded in enhancing its effectiveness thanks to a new molecule.
You have probably never heard of it and yet theonchocerciasis is the disease causing the greatest number of cases of blindness in the world. Also called “river blindness”, it affects nearly 18 million people, particularly in tropical Africa, especially along waterways in savannah areas south of the Sahara.
Caused by parasitic worm Onchocerca volvulus, onchocerciasis is spread by the bite of a fly infested with the larva, the blackfly. When they reach maturity under the skin, after one to two years, they form nodules which create intense pruritus (itching), but also a progressive weakening of sight, due to migrations by the female larvae. About 800,000 people are said to have suffered partial or total vision loss, due to local inflammation and lesions caused by the larvae.
A more effective treatment in 7 days
So far, no drug treatment has managed to put an end to the epidemic of onchocerciasis. In 2015, the Nobel Prize for Medicine was awarded to the Irishman William C. Campbell, the Japanese Satoshi Omura and the Chinese Youyou Tu for their fight against parasitic diseases and the development of treatments based on avermectin, a drug having a capacity to fight against parasitosis. Avermectin has a neurotoxic and neuromuscular effect in parasites and mosquitoes. It mainly attacks the glutamate-dependent channels present in the nerve and muscle cells of invertebrates, and absent in mammals. This is why it is generally very well tolerated in humans.
But the problem is that so far avermectin failed to kill the worms Onchocerca volvulus females, very resistant. Indeed, the worms causing onchocerciasis depend on the symbiotic bacteria Wolbachia during larval growth and at other stages of their life cycle.
Antibiotics that kill the Wolbachia rather than the worms directly can be effective, but require up to four to six weeks of daily treatment to achieve the kill rates needed to eliminate all the parasites. However, researchers have succeeded in reducing the duration of treatment by making it more effective. In an article published in the Proceedings of the National Academy of Sciences, scientists from the University of Liverpool, England, say they have discovered a molecule that makes the antibiotic effective in seven days to eliminate parasites. Called AWZ1066S, this molecule was chosen from 10,000 compounds, then modified to increase its effectiveness.
According to the researchers, this new treatment can be taken orally, while causing little damage to healthy intestinal bacteria, which makes it easily transportable to rural areas of countries affected by the onchocerciasis epidemic.
So far, evidence of the safety and efficacy of AWZ1066S has been limited to animal studies. New funding is now needed to continue the work. Finding funding is all the more important since, according to the study authors, this new treatment could also treat elephantiasis, a disease that causes significant swelling of body parts and is also caused by worms.
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