Via a presentation made today at the annual meeting of the American Society of Tropical Medicine and Hygiene:
Polio cases worldwide reached historic lows in 2012, and for the first time there were no new outbreaks beyond countries already harboring the disease, leaving researchers confident that a massive and re-energized international campaign to eradicate polio is on a path to success, according to presentations today at the annual meeting of the American Society of Tropical Medicine and Hygiene (ASTMH).
Globally there were 177 polio cases through October 2012, a drop from 502 during the same period last year.
Despite the dramatic drop, polio experts noted challenges in Pakistan posed by parents who refuse to vaccinate their children and in Nigeria where polio cases more than doubled in 2012 and threatened to re- infect currently polio-free countries. Pakistan, Nigeria and Afghanistan are the only countries where polio remains endemic and are the battle grounds of efforts to make polio only the second human disease, after smallpox, to be completely eliminated.
Steven Wassilak, MD, a medical epidemiologist and polio expert at the US Centers for Disease Control and Prevention (CDC), said new data from Pakistan show that of the two types of wild polio virus (WPV1 and WPV3) circulating in the country, the one known as WPV3 - or Type 3 - is close to being eliminated.
“There have not been any Type 3 cases reported for six months, which is the longest gap in incidence there to date,” he said. “CDC works with Pakistan officials to monitor different chains of transmission over time and Type 3 is now down to only one chain, which is an indication that we are close to breaking the last link of Type 3.”
CDC, which has led the effort to establish a global network of laboratories to track and sequence the genome of the wild polio virus, is one of four partners spearheading the Global Polio Eradication Initiative along with Rotary International, UNICEF and the World Health Organization (WHO), with great support from the Bill and Melinda Gates Foundation. In September, the partners along with leaders from Pakistan, Nigeria, and Afghanistan met at United Nations Headquarters in New York to reaffirm the Emergency Action Plan against polio, launched in May. The initiative includes a “surge of human resources” involving 4,000 people who have been deployed to complete the eradication effort.
New Study Finds Vaccine Refusals Remain Barrier to Elimination
At the ASTMH conference, Anita Zaidi, MD, a pediatrician at Aga Khan University in Karachi who serves on Pakistan’s National Immunization Technical Advisory Group, is presenting new data showing that while Pakistan has made major progress against polio by expanding immunization campaigns, the remaining challenge is not one easily solved by additional resources.
“We found that in Karachi, a key reason children fail to get immunizations is not due to lack of access, but because their parents refuse to participate,” Zaidi said. “That is a big challenge and not something that can be overcome only by expanding immunization campaigns.”
In a study published in the Bulletin of the World Health Organization (WHO), Zaidi and her colleagues found that in Karachi, “parent refusal was the most common reason given for the failure of children to participate in two recent polio supplementary immunization activities,” accounting for 74 percent of missed immunizations.