New polio cases threaten country, region and beyond

The Chadian Health Ministry and the UN have launched a polio vaccination drive targeting half a million children in the west of the country, as new cases of the crippling and sometimes fatal disease continue to emerge.

Despite previous vaccination campaigns, Chad has seen 27 cases of polio so far in 2008 -- including polio type 1, the most dangerous of the remaining serotypes -- up from 22 cases in 2007.

The resurgence is due in part to poor vaccination coverage, UN and government health officials say. In some regions only 50-60 percent of children receive routine vaccinations before their first birthday, according to the Chadian Ministry of Health.

“More than half of children under five have not been vaccinated against the disease,” the UN Office for the Coordination of Humanitarian Affairs (OCHA) in Chad said in a 30 October statement.

The World Health Organization (WHO) says infants should receive four doses of oral poliovirus vaccine in their first year.

A report by the UN Children’s Fund (UNICEF) says a number of factors contribute to the low coverage in Chad, including parental refusal, weak monitoring and insufficient training of medical teams.

One Chadian Health Ministry official estimated that about 2 percent of families refuse the vaccination out of fear.

“Sometimes people think the polio vaccine is something invented by the white people to sterilise the children; they think it’s directed against one group of people,” said Garba Tchiang Salomon, vaccination coordinator at the Health Ministry. “So they refuse the vaccinations, and unfortunately some who refused have seen polio attack their children.”

In neighbouring Nigeria, one of four countries where polio is endemic, health officials have long had to battle beliefs held by some Muslim leaders that the vaccine harms children. (See report on Muslim leaders calling for resuming polio vaccinations)

Silent and invisible

“Polio is quite dangerous because it can move silently and quite far,” Oliver Rosenbauer, spokesperson for WHO’s polio eradication group, told IRIN from Geneva. “Out of 200 infections you have just one case of paralysis, so as people [infected but not showing symptoms] travel about they can transmit the disease.”

Photo: Celeste Hicks/IRIN
A health worker in Chad marks a household to show that children there have received polio vaccination

Infections in 2003 in northern Nigeria, which shares a border with Chad, were blamed for re-infections in 27 countries -- as far as Indonesia -- that had eradicated the disease, Rosenbauer said. He added that this year Nigeria has seen an outbreak of polio type 1 and it has spread across West Africa; cases have been confirmed in Benin, Burkina Faso, Ghana, Mali, Niger and Togo.

Infections in west and central Africa are dangerous, he said, because the region has a large nomadic population, many people travel to Saudi Arabia for the annual Muslim pilgrimage and there is considerable migration within the region.

Children in five western regions of Chad -- Chari Baguirmi, Hadjer Lamis, Kanem, Lac and N’Djamena -- are being vaccinated against polio type 1. Vaccination teams are going door-to-door, looking for children and marking completed households. The campaign is to be followed by vaccinations against polio type 1 in the rest of the country, then against type 3 and measles early next year.

A highly infectious disease caused by a virus, polio mainly affects children under five, with one in 200 infections leading to irreversible paralysis, according to WHO. Five to 10 percent of these children die when their breathing muscles become immobilised. No cure exists for polio - only the vaccine for prevention. If administered multiple times, the orally-taken liquid can protect a child for life, WHO says.