Some 26,000 Nigerian health workers are going door-to-door in the northern state of Kano administering oral polio drops to children under the age of five. Kano has been the epicenter of the transmission of the crippling polio virus to other parts of the world since 2003 when the authorities suspended polio immunizations for 13 months. From Abuja, Gilbert da Costa reports for VOA.

Anas Mustapha, 14, at right, who was tested with the meningitis epidemic experimental drug, looks on as he stands with some children in Kano (File)

Polio fighters expect to immunize 4.6 million children under the age of five in Kano over the next four days.

Nearly all children paralyzed by polio are in northern Nigeria, where a year-long boycott of the vaccine in 2003 triggered an explosion of the disease. The disease was subsequently exported to more than two dozen countries worldwide.

Hard-line Nigerian Islamic clerics called for the boycott, claiming an immunization campaign was a US-led Western plot to render Muslims infertile. The government finally reigned in the boycott campaign, but the World Health Organization says up to 30 percent of children in the north have never had a single dose of vaccine.

In the bustling Kano metropolis, northern Nigeria's largest city of some 10 million inhabitants, Aminu Wada leads a group of polio victims working with vaccination teams to break down resistance to polio vaccinations in conservative neighborhoods. He told VOA steady progress has been achieved.

"We had many people with polio in Kano, but many years ago, every year we had 500, but now, from January to now, only 40 afflicted with polio in Kano because of the awareness. My members in the association they are going everywhere, mobilizing the people to agree to the immunization," said Wada.

Health officials say vaccine coverage has doubled countrywide from 35 percent in 2005 to 76 percent last year. But polio cases have nearly doubled this year in Nigeria as officials struggle to fight an outbreak set off by the polio vaccine itself three years ago. The vaccine-sparked outbreak has struck more than 100 children, including eight this year.

The World Health Organization has recently listed Nigeria, India, Pakistan and Afghanistan as the only polio-endemic countries in the world.