For millions of viewers, “river blindness” is what Sandra Bullock battled to traverse rapids blindfolded in Bird Box. In much of Africa, however, it is something more terrifying than any film, a disease that has stolen sight from the best part of a million people.
When you compare the amount of money spent trying to cure diseases, and the harm those diseases cause, river blindness may be the world's most neglected disease. However, the little that has been spent on the problem is bearing fruit, with a new drug treatment announced. Better still, the same drug could treat another neglected tropical disease.
Also known as onchocerciasis, river blindness is caused by the parasitic worm Onchocerca volvulus, and is spread by biting flies. The worm's larvae grow beneath the skin and create painful itching and disfigured skin for more than 15 million sufferers, mostly near African rivers, but also in some other tropical regions. Around 800,000 have suffered partial or complete loss of sight when the worms infected their eyes. The 2015 Nobel Prize for Medicine was awarded for the development of avermectin drugs, which have helped stem the damage onchocerciasis causes. Unfortunately, avermectin doesn't kill adult females, so the problem comes back.
The worms are extraordinarily tough and medications to kill their larvae have limited success. Onchocerca worms are dependent on symbiotic Wolbachia bacteria during larval growth and other stages of their life cycle. Ironically, this is the same genus of bacteria now being used to control mosquito-borne diseases such as dengue fever, but while Wolbachia interferes with mosquito breeding, the worms depend on it.
Antibiotics that kill Wolbachia rather than the worms directly can be effective, but require four to six weeks of daily treatment to achieve necessary kill rates. A paper in the Proceedings of the National Academy of Sciences claims the same thing can be done in seven days with an antibiotic going by the handle AWZ1066S until it is given a proper name.
A predecessor molecule of AWZ1066S was selected from among 10,000 compounds, and then modified to increase its efficiency. Researchers from the University of Liverpool have established their product can be taken orally, while doing little damage to healthy gut bacteria. Like the shortness of the treatment program, delivery through pills rather than injections is essential for a disease that plagues rural areas of countries with limited health systems.
So far proof of AWZ1066S' safety and effectiveness has been limited to animal studies, and it won't be easy to find the money for clinical trials, but it could provide a double reward. Elephantiasis, a disease that leads to drastic swelling of body parts, is caused by a related species of worm. Since these are also Wolbachia-dependant, the authors expect elephantiasis will be controlled by AWZ1066S equally well.