Mar 22, 2012 (CIDRAP News) – Polio cases in Africa were almost halved in 2011, but the disease shows worrisome trends in some countries, health officials reported today as the continent geared up to vaccinate 111 million children against the disease.
Although polio cases tripled in Nigeria, Africa's only polio-endemic country, from 21 in 2010 to 62 in 2011, the continent's overall count dropped from 657 in 2010 to 350 in 2011, according to an update in Morbidity and Mortality Weekly Report (MMWR) from the World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC).
The 1-year drop, however, was entirely attributed to a decline in cases reported from periodic outbreaks in one country, the Republic of Congo.
Eight African countries experienced intermittent polio outbreaks in 2011, with transmission interrupted in six of them, according to the report. However, such outbreaks accounted for just 58 cases in 2011, compared with 477 in 2010.
The lion's share of this drop resulted from the situation in the Republic of Congo, which reported 441 polio cases in 2010 but only 1 in 2011. Cote d'Ivoire had the most outbreak-related cases in 2011, with 36, after recording none in 2010.
Last year's trends were mixed in the three African nations where polio transmission has become reestablished. Cases dropped from 33 in 2010 to 5 in Angola and from 100 to 93 in the Democratic Republic of the Congo (DRC) but increased from 26 to 132 in Chad.
"Ongoing endemic transmission in Nigeria poses a major threat to the success of GPEI [the Global Polio Eradication Initiative]," the report states. "Vigilant surveillance and high population immunity levels must be maintained in all African countries to prevent and limit new outbreaks."
Massive vaccination campaign
In response to continued polio cases, a GPEI initiative by United Nations agencies, African health ministries, and local communities is set to launch a campaign tomorrow to administer oral polio vaccine to 111 million children below age 5 in 20 western and central African nations.
The effort will involve tens of thousands of door-to-door volunteers, according to a press release yesterday on AllAfrica, which aggregates content from African news agencies. Nigeria, which will start its campaign a week later because of logistics, aims to fully vaccinate 57.7 million children.
Nineteen other counties plan to vaccinate 53.3 million children in 4 days: Chad, the DRC, the Central African Republic, Niger, Cameroon, Benin, Burkina Faso, Cape Verde, Cote d'Ivoire, Gambia, Ghana, Guinea, Guinea Bissau, Liberia, Mali, Mauritania, Senegal, Sierra Leone, and Togo.
"This exercise should bring us closer to reaching our goal of interrupting wild polio virus transmission in our region in 2012," the WHO's Regional Director for Africa, Luis Sambo, said in a UN news release yesterday.
"Either we succeed in eradicating polio today or this initiative will falter tomorrow and polio will explode," David Gressly, UNICEF's regional director for west and central Africa, said in the release.
The GPEI was launched in 1988 by national governments, the WHO, UNICEF, Rotary International, and the CDC and is supported by the Bill & Melinda Gates Foundation. At the time, more than 350,000 children were paralyzed every year in more than 125 countries. Since then polio incidence has fallen more than 99%, according to the UN release.
Last year, the agency said, 650 polio cases were reported worldwide. India, however, once a hotbed of the disease, was declared free of polio in January, reducing the number of polio-endemic countries to three: Nigeria, Afghanistan, and Pakistan.
Elsewhere today, a WHO official warned Pakistan that it could face adverse measures such as travel and visa restrictions from some countries if it does not contain polio within its borders, Gulf Today reported.
Bruce Aylward, MD, MPH, assistant director-general of polio, emergencies and country collaboration, said the global community has expressed anxiety of late over widespread polio in Pakistan.
"Why would countries that have invested millions of dollars for the eradication of polio tolerate any possibility of the virus travelling from Pakistan to their country?” he asked. "Some countries in their individual capacities want to impose travel restrictions that are not in the benefit of Pakistan and must be avoided. It must be clarified that WHO is not a party to any of those plans."
He added, however, "The concerns of the international community are certainly not unfounded."
Aylward said many countries were asking for steps like those taken by Saudi Arabia, which issued a special travel advisory requiring pilgrims from Pakistan to be vaccinated before entering the country.
Pakistan reported 198 polio cases in 2011, 30% of the global total. So far this year the country has seen 14 new cases, representing 15% of the world's total.
The country has been motivated, however, by India's polio-eradication success and is now undertaking an effort to immunize more than 23 million children nationwide in 3 days, according to a Mar 20 Voice of America (VOA) story. Efforts in the country have been hampered by years of natural disasters, misinformation, and war, the report said.
India may drop trivalent vaccine
In other polio news, India may soon shelve its trivalent (three-strain) oral polio vaccine and rely solely on a bivalent form, the Times of India reported.
Experts say the risk of contracting vaccine-derived polio are elevated with the trivalent vaccine. India's only polio case this year—reported this month—was vaccine derived. After the country first introduced the bivalent vaccine in 2009, it saw a 94% drop in polio cases, according to the story.
Indian officials are awaiting a global recommendation from the WHO in April on whether to stop use of the trivalent form.
Mar 23 MMWR report
Mar 21 AllAfrica news release
Mar 21 UN news release
Mar 22 Gulf Today story
Mar 20 VOA article
Mar 20 Times of India story