New drug raises hope of ending river blindness: WHO

By Laura MacInnis

GENEVA (Reuters) - A drug normally prescribed to pets has raised hopes that river blindness, an infectious disease that threatens 100 million people, can finally be wiped out, the World Health Organization said on Wednesday.

Moxidectin, now used to treat parasites in dogs, cats, horses and cattle, shows potential to destroy the worms that cause river blindness, whose debilitating symptoms include loss of sight, severe rashes and lesions, according to the WHO.

"If moxidectin kills not only the larvae but also sterilizes or kills the adult worms, it has the potential to interrupt the disease transmission cycle within around six annual rounds of treatment," it said in a statement.

The announcement of clinical trials for the drug aligns with a revival of hope that river blindness, whose formal name is onchocerciasis, can be eradicated instead of just controlled.

The WHO proclaimed the end of smallpox in 1980 after an eradication campaign that began in 1970, and has been working for more than 30 years to stop the transmission of polio, which remains endemic in Pakistan, Afghanistan, India and Nigeria.

River blindness has special significance for the United Nations agency, which launched an eradication campaign in 1970 using insecticide to kill the blackflies that transmit the disease-causing worm larvae.

The program came close but did not fully destroy the blight, which is depicted in a statue outside the WHO's Geneva headquarters showing a young boy leading a blind elderly man with a stick.

The river blindness campaign later changed gears to try to control the effects of the disease, using Merck's drug ivermectin as treatment.

Moxidectin, which Bayer Animal Health uses in its anti-flea treatments for dogs and cats, has been reformulated by Wyeth for human use.

Wyeth Pharmaceuticals vice president Henriette Ukwu told Reuters the drug would be tested for use in preventing and treating river blindness.

Clinical trials are set to take place in Ghana, Liberia and the Democratic Republic of Congo over the next 2-1/2 years.

Ukwu said the company was providing the drugs free of charge for the trial and planned to seek regulatory approval for their wider distribution if it is successful.

"There is no commercial interest for this product," she stressed, saying the company would work to ensure those who need the treatment can access it through existing aid channels.

(For a WHO factsheet on river blindness and its effects, see: www.who.int/topics/onchocerciasis/en/)

(For details on moxidectin for animal use, see the Bayer Health Care site: www.moxidectinfacts.com/questions.cfm)

(Editing by Stephanie Nebehay and Richard Meares)