Just one year ago, India seemed poised on the edge of polio eradication. Having reduced the incidence by 98 percent in less than a decade to only 66 cases in 2005, health officials predicted the country would be polio-free by the end of this year.
Instead, an outbreak in the northern Indian states of Uttar Pradesh and Bihar this summer quadrupled last year's total caseload in just a few months and spread cases as far abroad as Africa.
A reported 288 cases occurred in India by mid-September, but over half of these were reported in the month of August alone – most of them in the industrial city of Moradabad, in Uttar Pradesh, and largely among children in Muslim communities.
By mid-September, cases of the same virus were confirmed in Angola, Bangladesh, Congo, Nigeria, and Nepal, countries where the disease has been successfully eradicated, and in Afghanistan and Pakistan, where it has not. Earlier this year, the virus was also reported in Singapore.
The outbreak and its migration underscore how difficult it is to eradicate an infection in impoverished countries, especially where poor sanitation, malnutrition, sectarian mistrust, and religious and cultural obstacles can frustrate immunization efforts, according to Johan Aarli, MD, President of the World Federation of Neurology.
He noted that there are only four major polio virus “reservoirs” in the world: Northern India, Pakistan, Afghanistan, and Nigeria.
“Since 2000, the number of new polio cases in these areas has not dropped significantly despite our immunization efforts. It seems to be a constant, this failure to interrupt wild-type polio virus transmission, and now we're seeing new cases in countries we thought were polio-free,” he told Neurology Today in a telephone interview. “The main problem is simply insufficient routine coverage of infants and young children.”
Dr. Aarli said that although polio is still a concern for India, he remains optimistic that eradication is still within reach. “The country has made much progress with its eradication campaign and has an excellent network of polio laboratories. They've sequenced the specific virus in Northern India and the number of clusters has been reduced, so there is some progress,” he said. “In India health officials are being very alert, but it's a complex issue on many levels.”
The Global Polio Eradication Initiative, a consortium of national governments, Rotary International, World Health Organization (WHO), UNICEF, and the US Centers for Disease Control and Prevention (CDC), has spearheaded immunization efforts in developing countries with major success over the past 20 years.
Prior to large-scale polio immunization, there were as many as 35,000 cases in India each year, but eradication efforts in the mid-1990s reduced the annual number to around 2,000. The program intensified in 1999–2000 and the annual case rate fell to around 200, but a large outbreak in the same region infected about 1,600 persons in 2003.
In May 2005 a new version of the polio vaccine was introduced in a major campaign in India, one that had proved very effective in Africa, but once again many children in the Uttar Pradesh area were not vaccinated, said CDC's Jay Wenger, MD, who also oversees polio eradication efforts in India for the World Health Organization.
“There were only a couple hundred cases, but then resources shifted to other areas, the program let up, and many children in this region were skipped,” he said.
“It appears now that over a period of six to eight months there was some slippage in community immunization. Call it campaign fatigue, but it appears as many as 25 percent of the kids here were skipped during that period, and that left a big enough hole for the disease to re-emerge,” he told Neurology Today by telephone from Uttar Pradesh.
Like a game of ping-pong, effective door-to-door immunization in one district has invariably led to new cases in other districts where efforts are less focused, especially in minority communities, according to Dr. Wenger.
David L. Heymann, MD, WHO Executive Director of Communicable Diseases, and WHO Representative for Polio Eradication since 2003, attributed the gaps to a failure of some district health commissions to be “fully engaged “ in prior vaccine campaigns, a situation that is being rectified.
Health officials have pledged renewed commitment to eradication efforts as the potential scope of the outbreak emerged and began drawing international concern, he told Neurology Today in a telephone interview. United Nations Secretary General Kofi Annan sent a letter to Indian health authorities expressing his concern over the outbreak and the UN's support for renewed immunization efforts.
Nonetheless, Dr. Heymann said the actual number of infected individuals is probably much greater than those identified to date. “Only cases of paralytic polio are reported, and for every one case that results in paralysis, there are probably as many as 100 cases that do not,” he stressed. “This outbreak is increasing the risk of national and international spread of polio virus, and although there are more cases in Nigeria, India is currently the only country exporting the virus.”
HIDDEN RESISTANT TO TREATMENT
In Uttar Pradesh and other parts of the region, poverty and disease are far bigger obstacles to immunization than religious, political, or cultural issues, noted Linda Venczel, PhD, an epidemiologist stationed at the CDC in Atlanta.
“I visit Uttar Pradesh three or four times a year, and it is difficult to tease out all the issues involved. Sanitation is poor and there are a lot of other diseases, and many of these children often have diarrhea, which prevents the enteric vaccine from establishing itself in the gut and renders it ineffective.”
In addition, many people in these communities feel disenfranchised from the government, she said. “There's a lot of tension and resistance in these neighborhoods. Many people simply hide their children or don't answer the door,” she told Neurology Today in a telephone interview.
There have been rumors that the vaccine is a plot to sterilize male children, and some Muslim clerics have issued fatwas [edicts] calling on followers to resist vaccination, although not recently. Nonetheless, “These rumors are still floating around,” said Dr. Wenger.
Dr. Heymann said UNICEF is working with community religious leaders who have pledged to spread the message that their children must be vaccinated. Instead of fatwas against vaccination, clerics are now instructing Muslims to immunize all children, and Saudi Arabia has barred children under the age of 15 to travel from the region to Mecca for the Muslim religious pilgrimage, or Haj. All pilgrims from Nigeria must show proof of immunization as well, he said.
At the same time, health workers have started ensuring that immunization teams include women, in recognition of strict Islamic rules governing interaction between married women and men outside of the family. They are also handing out other medical supplies on vaccine visits such as vitamins, vermicides, and mosquito nets.
“One thing that has been made clear is that when health officials visit one of these homes there is usually suspicion,” said Dr. Heymann. “‘Why are they only bringing us vaccine when we have so many other health issues?’ they ask. “We've learned that we have to bring other medicine as well.”
Health officials are also being deployed on local trains and the initiative is trying to find other creative ways to address these issues, but there remain areas where local immunization efforts remain almost impossible, noted the CDC's Dr. Venczel.
“We've put so much effort into this, and there's been a lot of progress, but in places like the Afghan-Pakistan border it's just too dangerous for any Westerners, even health workers. I think we need to have ‘Days of Tranquility’ like there were in South America where all sides agreed to stop fighting so health workers can just immunize these kids.”