Polio cases slowing in Pakistan spur hope for global elimination

A child in Pakistan is given the polio vaccination (Getty Images)

Polio cases caused by one of two circulating strains of poliomyelitis virus weren't reported in Pakistan in six months, speeding global eradication of the crippling disease.

Type-3 polio is close to being eliminated in Pakistan, one of three countries in the world where transmission has never been interrupted, researchers said in presentations Tuesday at a medical meeting in Atlanta.

Globally, 177 polio cases were identified from January to October 2012, compared with 502 during the same period last year. Fighting the paralyzing disease has been challenging in Pakistan, where a World Health Organization doctor was injured in July in a gun attack in Karachi. He was returning from supervising a polio vaccination campaign — a program the Taliban has opposed elsewhere in the country.

"There have not been any Type-3 cases reported for six months, which is the longest gap in incidence there to date," Steven Wassilak, a medical epidemiologist with the Centers for Disease Control and Prevention in Atlanta, said in a statement. "CDC works with Pakistan officials to monitor different chains of transmission and Type-3 is down to only one chain, which is an indication that we are close to breaking the last link."

The attack in the southern port city of Karachi was a month after Pakistan's Taliban guerrilla movement said it would oppose polio immunization in the country's northwestern tribal areas of North and South Waziristan to protest missile strikes by U.S. unmanned drone aircraft.

About 250,000 children in tribal areas located along Pakistan's border with Afghanistan won't get the vaccine because of the opposition by the Taliban, the BBC reported July 16, citing WHO officials it didn't identify.

Polio control is also being hindered in urban Karachi by parents refusing to allow vaccinators to give their children the two drops of the oral vaccine that will prevent infection, said Anita Zaidi, a pediatrician at the city's Aga Khan University.

"Efforts should focus on building trust through grass- roots effort using community elders in populations with high vaccine-refusal rates," she said. "By providing vaccination at mass transit sites, such as bus routes used to travel up country throughout the year, we can at least isolate the viral reservoirs and make sure we avoid what happened last year, which was exporting the virus to China."

The other endemic countries are Afghanistan and Nigeria.

India hasn't reported a polio infection since January 2011 and the World Health Organization's Southeast Asia region will be certified polio-free in 2014 if no new cases arise, Wassilak told the annual meeting of the American Society of Tropical Medicine and Hygiene.