Fighting in Afghanistan and Pakistan meant that polio did not go well in those countries in 2007, a World Health Organization report said last week. They are two of the last four nations that have not the disease. In Afghanistan, most cases were in provinces under Taliban control. In Pakistan, many were in the remote tribal border areas where Osama bin Laden is still being pursued and local are battling the government. Polio experts see the territory differently: as one "epidemiological block" with two transmission corridors, one in the mountainous north, where cases of the polio known as Type 1 are common, and one in the flatter south, where Type 3 prevails. Tribes migrate east-west across the borders, following harvests, routes and jobs. Polio went as far southeast as Karachi, where there is no fighting, but immunization drives "remain weak," the report said. Crowded and petty corruption disrupt efforts, an expert said. The report spoke of a in August when the Taliban started letting vaccinators work in their territory. "We dialogue with NATO and tell them, 'These are the days of our campaigns, these are our people — don't them!'" said Dr. Bruce Aylward, the campaign's director. Eradication requires mustering thousands of health workers every few months to visit homes and give drops to every child under 5. Both countries tried to vaccinate their whole four times in 2007, and each held seven regional drives.