River blindness treatment receives Nobel Prize

River blindness treatment receives Nobel Prize

This year's Nobel Prize in Physiology or Medicine is shared by two researchers whose discovery is leading to the eradication of onchocerciasis, or "river blindness," across the globe.

"The development of these drugs is another step in the quest to preserve sight."

The awarding of such a prestigious prize brings river blindness and other parasitic diseases that affect eye health to the forefront, says Bradley Lane, O.D., who practices in Princeton, West Virginia, and is a member of the AOA Health Promotions Committee. "It also reminds us that we in the U.S. are fortunate and privileged, and we have a responsibility to continue to do this research for the rest of the world."

River blindness occurs when the parasitic worm Onchocerca volvulus is spread to humans by the bite of an infected black fly, which lives near rivers in Africa and other parts of the world. River blindness is the second-leading infectious cause of blindness worldwide, according to the World Health Organization. It affects more than 18 million people and causes 270,000 cases of blindness. Ninety-nine percent of those infected live in Africa, though the disease also occurs in the Americas and the Arabian Peninsula.

Scientists William C. Campbell and Satoshi Ōmura discovered a new drug, avermectin, whose derivative, ivermectin, has dramatically reduced the incidence of river blindness. They share the Nobel Prize with scientist Youyou Tu, who discovered artemisinin, which has become a standard treatment for malaria.

"These two discoveries have provided humankind with powerful new means to combat these debilitating diseases that affect hundreds of millions of people annually," the Nobel Prize organization said in a statement.

Discovering a new class of drugs
Ōmura isolated new strains of streptomyces, which live in the soil and were known to produce many antibacterial agents, according to the Nobel Prize organization. Campbell, an expert in parasite biology, acquired Ōmura's streptomyces cultures and explored their efficacy. He discovered one component, later named avermectin, that successfully killed parasites in domestic and farm animals. It was later modified to become ivermectin (Mectizan®) and was found to be effective at killing parasite larvae in humans.

Ivermectin works both preventively, through programs that spray river areas where the black flies breed, and as a treatment for people infected with the parasite. Ivermectin has also been shown to work against several other parasitic diseases as well.

"The goal of optometry is to prevent and eventually eradicate blindness across the globe," Dr. Lane says. "The development of these drugs is another step in the quest to preserve sight." 

While optometrists might encounter river blindness when volunteering overseas, it is becoming more and more rare. Colombia became the first country to eradicate the disease, followed by Ecuador and Mexico. Guatemala is on the verge of eradication.

October 20, 2015

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