Yaws eradication will need millions of donated antibiotics, says WHO
World Health Organization says bacterial skin disease requires drug companies to give large supplies of single-dose tablets
21 February 2014 | Geneva -- The World Health Organization has stepped up efforts to eradicate yaws, described as the "forgotten disease", after the discovery of a single-dose oral antibiotic that can cure it.
Wiping out the bacterial skin disease that causes weeping ulcers would, however, depend on whether drug companies were prepared to donate millions of tablets, the WHO said.
Untreated, the disease progresses to the bones, causing severe disfigurement and disability. It mainly affects under-15s in poor, remote populations.
Only 12 countries – three Pacific islands, eight African countries and Indonesia – are affected by yaws. A global vaccination programme in the 1950s treated more than 300 million people and rid 90 endemic countries of the infectious bacteria.
In the remaining endemic countries, up to 10% of children suffer skin ulcers, which suggests that between 40% and 60% have the infection in their bloodstream. These latent cases can become sources of reinfection, said Oriol Mitjà, a technical adviser for the WHO's neglected tropical diseases department who works on the yaws treatment programme in Papua New Guinea
"How can we morally justify not using such a simple and inexpensive tool to rid the children of these communities of an infection that causes years of suffering?" he said.
The WHO set 2020 as the deadline for the eradication of yaws, and has successfully carried out treatment campaigns using the new antibiotic in Congo-Brazzaville, Ghana, Papua New Guinea and Vanuatu. With a single dose given to everyone, the disease can quickly be eliminated from the community, said Mitjà.
"We were very happy to see that about 95% of the population living in the four countries took a single dose of the drug. And we are encouraged by the results, that after one round of treatment the disease goes down dramatically," said Kingsley Asiedu, responsible for yaws in the WHO's neglected tropical diseases department.
In Lihir in Papua New Guinea, the number of new cases dropped by 90% just six months after the antibiotic was administered, Asiedu said.
But the air of optimism is tinged with uncertainty about where funding for the antibiotic will come from.
The next step, according to Asiedu, is to expand the treatment into other countries, but this will require more resources, particularly the drug azithromycin.
"If we leave it to a country's ability to buy the drug, it's going to really delay the speed at which we can reach the target. Our basic objective is now to secure the donation of azithromycin. We're trying to discuss with Pfizer whether it will be interested to assist in yaw eradication efforts," he said.
"It's up to the pharmaceutical companies to make the donation of 200m tablets. There are currently 40 million people who are at risk from the disease and we need to treat them all," Mitjà said.
As the treatment requires only one round, Asiedu is sure that if they get the funding yaws can be wiped out within six years. The ability to reach remote areas would not be a problem, he said, because previous vaccination programmes had successfully reached them.
Matthew Coldiron, a doctor who took part in a Médecins Sans Frontières campaign to eradicate yaws in the remote northern regions of Congo-Brazzaville, said, however, that treating Aka pygmy communities in the most inaccessible regions of the tropical rainforest was "an immense logistical burden".
"One of the major places where yaws is present is in the central African rainforest. Logistic access and insecurity is going to make it a real struggle to eradicate the disease," he said.
There is also concern that the bacteria that causes yaws will become resistant to azithromycin, according to Michael Marks, a Wellcome Trust clinical research fellow at the London School of Hygiene and Tropical Medicine. Resistance to the drug has occurred in the bacteria that causes syphilis, which is closely related to the yaws bacteria, he said.
"Monitoring for the development of resistance in the yaws bacteria will be extremely important during the yaws eradication programme," he said. "Although there are challenges to overcome, if we can maintain the momentum we have, then worldwide elimination is a realistic goal."
Health experts see the yaws eradication effort as an indicator of similar global drives to wipe out other diseases. "If we can't eradicate something like yaws, why are we so concerned about eradication of other diseases. This is the simplest disease to eradicate, medically speaking," Coldiron said.
"Yaws is going to be the second disease to be eradicated from the world after smallpox. This will probably encourage other public health officials to pursue eradication of other diseases, such as malaria and tuberculosis," Mitjà said.