A polio epidemic raging through Yemen, with 63 confirmed cases so far, is expected to paralyse 200 children before coming under control, the World Health Organisation’s top expert said on Tuesday.

The United Nations agency, campaigning to halt spread of the crippling disease by year-end, expects to meet the target in Asia, but the battle is still being waged in Africa, said David Heymann, head of WHO’s global polio eradication initiative.

He was speaking in an interview on the sidelines of the WHO’s annual World Health Assembly of 192 member states.

“In Yemen, we expect a major outbreak with probably more than 200 cases. This is the price paid for not keeping up immunisation coverage,” said Heymann.

For each child paralysed by the disease, 200 more are silent carriers, able to transmit the virus without showing symptoms apart from perhaps a fever, he added.

Yemen, which had been polio-free since 1996, conducted vaccinations in late April as it was deemed as high-risk of re-infection from nearby Sudan. It plans to hold further nationwide immunisation rounds in May and June.

The WHO has battled setbacks in the last two years since the northern state of Kano in Nigeria banned immunisation for 10 months. The crippling virus spread across Africa, crossed the Red Sea into Saudi Arabia and Yemen, and reached Indonesia - infecting 16 previously polio-free countries in all.

Rapid vaccination of children can contain such outbreaks.

“We believe now that Asia and Egypt will interrupt transmission this year. Commitment is high and their surveillance activities have dramatically increased,” Heymann said.

MAY TAKE OFF

But he declined to forecast until August whether polio transmission could be halted this year in Africa, where case numbers are falling across the region against last year.

“It is feasible we could interrupt transmission. It is the low season now, but when the rainy season comes in July or August, transmission may take off,” he said. “It is possible Africa can do the job very rapidly with political will.”

The viral disease of the brain and spinal cord, which mainly affects children under five, can cause irreversible paralysis in a matter of hours.

Some 1,268 cases were recorded worldwide last year. So far this year there have been 155 cases, nearly half of them in Nigeria, the virus’ largest reservoir in Africa.

The latest epidemiological evidence shows that polio’s grip is “rapidly slipping” in all three key endemic countries - Nigeria, India and Pakistan, the WHO says.

But polio-free parts of Africa including Somalia are still “under siege”, deemed particularly vulnerable as immunisation rates are low and health services poor, it says.

Indonesia, battling its first polio outbreak in a decade, has reported eight confirmed cases in the last month. Health officials in Jakarta said on Monday that it had nearly contained the outbreak, crediting fast vaccination in affected areas.

When the WHO initiative was launched in 1988, 350,000 children were crippled each year by the disease in some 125 countries.