VOA标准英语2011--Cheaper, Safer Pill Targets Tropical Parasite（在线收听）

Cheaper, Safer Pill Targets Tropical Parasite

Scientists have developed a new version of a drug used to treat leishmaniasis. The new formulation may help better battle this tropical parasitic disease.

Leishmaniasis is transmitted by the bite of certain sand flies.

The World Health Organization says as many as 12 million people are infected with the leishmaniasis parasite.

Cutaneous leishmaniasis, which affects the skin and mucus membranes, is the most common form.

But the more serious form, called visceral leishmaniasis, attacks the immune system. Without proper treatment, it's often fatal. One of the drugs used against leishmaniasisis is amphotericin B.

Amphotericin is effective, but it has from numerous drawbacks. It's expensive, it has to be given as an injection, it's highly toxic to the kidneys, and it loses effectiveness if exposed to high temperatures.

University of British Columbia researcher Kishor Wasan has been testing an improved version he developed.
　

Ansar Deldar, 4, shows signs of leishmaniasis, a common disease among children in Afghanistan.

He says his new formulation addresses all these shortcomings: it's much cheaper, for one, and it can be taken by mouth.

"It's tropically stable," Wasan says. "We've been able to develop a formulation that does not need refrigeration, and that's a huge factor in the developing world. And finally, we're looking at a formulation that is very effective, but does not have that kidney toxicity."

To test the effectiveness of his new version of amphotericin B, Wasan sent samples to a laboratory at another university, where it was used to treat mice infected with visceral leishmaniasis.

"And the results were just remarkable," he says. "We found greater than 99 percent reduction in the parasitic load in less than five days, and remarkably, in 60 percent of the animals, we completely eradicated the infection."

After the positive animal-test results, Wasan is now seeking funding to begin human trials.

The new formulation for amphotericin B may be useful against other conditions, too. The drug is also used to treat fungal infections in people with compromised immune systems, such as HIV patients and organ transplant recipients.

"The impetus originally to do the work was actually in the fungal infections," Wasan says. "Physicians wanted a cheaper, more accessible form of amphotericin B than the injectable. So the oral formulation was going to help in those situations as well. So, yeah, there actually are multiple uses for this formulation."