[remedy River. A woman receives ivermectin in his village in Rukungiri, Uganda.
Andy Crump / WHO / APOC / TDR
Cases of parasitic infection known as river blindness or onchocerciasis, fell dramatically in Africa in the 2 recent decades, thanks to large donations of a drug by the pharmaceutical company Merck. Now, a new study suggests that these programs can eventually eradicate the disease. "It's fantastic," said Uche Amazigo, Director of the African Programme against onchocerciasis, based in Ouagadougou, Burkina Faso. "For us in Africa, this is an important step."
onchocerciasis - often simply called "river blindness" - is caused by Onchocerca volvulus , a nematode worm that is transmitted from person to person by many species of Simulium black flies. The adult worms mate inside the human body, and the female produces a large number of microscopic larvae, called microfilariae. The larvae cause intense itching and a severe immune reaction when they die; when they colonize the eye can cause blindness.
initial control efforts have focused kill black flies around fast rivers where they prefer to breed. But after Merck has set up a donation program for ivermectin in 1987 - which is sold in the US as well and is active against many other parasites - annual or biannual treatment rounds with the drug proved more effective. Ivermectin paralyzes and kills the microfilariae; it also reduces the fertility of adult worms, but does not kill them. This works great to prevent blindness and other symptoms, but no one knew if the drug alone could completely stop onchocerciasis transmission
In the new study, researchers surveyed the places where treatment by ivermectin has been going on longer :. Three regions Mali and Senegal, which were distributed the drug for 15 to 17 years. The team verified nearly 18,000 people in 126 villages for O. volvulus less than 1% were tested positive. Of more than 150,000 black flies captured in the same areas, less than 0.05% have been able to transmit the worm. At these levels, the models suggest that the disease is linked to eventually peter says Hans Remme, parasitology World Health Organization retired who participated in the study as a consultant.
Next, the researchers stopped the treatment with ivermectin in five eight villages in each region. (Given the importance of whether the treatment can be stopped safely, it was considered ethical provided that the villages were monitored carefully for signs of resurgence, said Remme.) But the disease did not return. Among nearly 2,300 people were tested from 16 to 22 months later, no one had worms, while the number of infected flies remained extremely low, today reports the team in PloS Neglected Tropical Diseases . It is the first evidence, Remme said that stopping treatment with ivermectin is safe
In the next study phase, treatment was interrupted through two of the three regions. if the results are similar, Mali and Senegal ivermectin consider dropping altogether, said Remme. The chances of O. volvulus would stage a comeback are slim, he said, partly because men and women to need to meet within a single individual spread.
similar success may be more difficult in countries such as Cameroon and the Democratic Republic of Congo, which had higher transmission levels prior to treatment and are home to black fly species that spread them to more efficiently, said Remme. But a new drug called moxidectin, currently under study, could reduce the clearance time for it to target the long-term adult, in addition to their microscopic offspring. Nobody talks about eradication - the elimination of a disease of the entire planet - for now, but "we can really start to shrink the map onchocerciasis in Africa," said Amazigo
Merck, which already. given some 2.5 billion ivermectin tablets valued at $ 3.5 billion, said it will continue the program as long as necessary. "We dreamed that a step like this could be a day possible, "said CEO Richard Clarke in a statement released by the company today.
0 Komentar