Yala, Pattani and Narathiwat are of particular concern because the situation there has made it inaccessible to the nationwide "supplementary" polio immunisation programme, said Thawat Suntrajarn, head of the ministry's Disease Control Department.

The area is also adjacent to Songkhla and Satun provinces, where fishing boats arrive from certain islands in Indonesia where polio re-emerged last year after a decade, he said.

The ministry plans to carry out a nationwide polio vaccination programme twice, on December 13 and January 17, to further safeguard against the viral disease resurfacing.

"We don't know if the three southernmost provinces will follow the scenario of [Pakistan and Afghanis-tan] or not," said Dr Somchai Peerapakorn, the World Health Organisation's Thailand National Professional Officer.

Pakistan and Afghanistan, along with Nigeria and India, are the four countries in the world where polio is endemic. These four countries have been found to be persistent sources of polio infections in 12 other countries, including Indonesia, where the virus had been successfully eradicated years ago.

However, Somchai said, health workers in violence-affected areas of Pakistan and Afghanistan enjoyed better working conditions than those assigned to vaccinate children in the violence-plagued three southernmost provinces. In Afghanistan, for example, temporary cease-fires were agreed upon to allow the polio immunisation programme to reach the target population, unlike in the deep South, he said.

Besides the five southern provinces, the health ministry is focusing its polio vaccination programme on Bangkok. "The reason is that the city is a centre for migrant workers from several countries," said Thawat, adding that it was not easy to identify this section of the population because most of them were illegal immigrants and in hiding.

Ministry of Labour figures show that there are about 300,000 immigrants registered in Thailand, but the actual number could be closer to three million, said Thawat.

Public Health deputy permanent secretary Dr Kitisak Klubdi said the ministry encourages Thais with children aged five and below and immigrants, legal or illegal, with children aged up to 15 to be vaccinated against polio on December 13 and January 17. A particularly intensive vaccination programme will be carried out in the six high-risk provinces, Kitisak said, adding that the ministry would work with the Southern Border Provinces Administration Centre to reach as much of the target population in the area as possible.

Moreover, year-round surveillance to detect children with signs of polio, including limp and lifeless limbs, will be strengthened. Symp-toms were observed in about 350 children last year but none of them turned out to be polio cases, he said.

Arthit Khwankhom

The Nation