Poliovirus has been eliminated in most of the developing world. Its eradication has been primarily due to the Global Polio Eradication Initiative (GPEI), a multilateral proposal passed by the World Health Assembly in 1988. However, three countries—Afghanistan, Nigeria, and Pakistan—stand between the GPEI and its goal of making polio the world’s second eradicated virus.

The Global Polio Eradication Initiative is an international health initiative 20 years in the making. The project involves tens of thousands of vaccinators scouting people door-to-door in villages in developing countries—many of which are highly inaccessible and dangerous. Equipped with little more than GPS systems, vaccinators must navigate the shifting political landscape of the developing world in search of the disease.

The biggest challenge ahead for the GPEI lies in the recent rise in local resistance to vaccination efforts. The gunning down of nine vaccination workers in Pakistan’s largest city in December 2012 resulted in the suspension of the GPEI’s vaccination campaign and its 225,000 workers—a tragedy for which Taliban-linked militants are largely thought to be guilty. As political pressures mount, vaccinators are missing key opportunities to improve the situation. The success of the campaign relies on the crucial dry season—the next two months— during which the virus is weakest and spreads least effectively.

Poliovirus primarily affects children under five years of age. The virus enters the body through the mouth and multiplies in the intestinal tract. It is then shed into its surroundings through feces. Once in the environment, polio can spread rapidly through communities, hitting those with poor hygiene and shoddy sanitation infrastructure the hardest.

Most infected people have little to no symptoms, so cases often go unrecognized. However, in its most severe occurrences, poliovirus can lead to infantile paralysis and degenerative crippling through inflammation of the spinal cord’s grey matter and the death of motor neurons.

While there is no cure for polio, the vaccination is over 90 per cent effective. If such efforts are halted, it will become increasingly difficult to contain the disease. The more time that is lost in the GPEI campaign, the more likely it is that polio will spread back out into other areas of the world—reversing any efforts made by this worldwide program. Furthermore, steps need to be taken on a global scale to prevent the re-emergence of mutated vaccine-derived polioviruses that may be prevalent in small numbers.

Resistance to vaccination efforts stems from a variety of reasons. Attitudes of distrust and skepticism towards Western immunization workers are prevalent among many Islamic militant groups and the general public following the CIA’s hepatitis vaccination campaign ruse. Last year, the CIA sponsored a widespread vaccination effort against hepatitis in a failed attempt to collect DNA from children living in Osama bin Laden’s compound in northern Pakistan as confirmation of his whereabouts. Not only did the CIA fail to obtain DNA samples, but it also fostered a lack of trust amongst Pakistanis and vaccination workers.

Extremist groups also crudely associate polio workers with the devastating U.S. drone strikes responsible for killing civilians, giving rise to anti-West sentiments that may continue to lead to violent attacks, like last month’s shootings.

Efforts are further impeded by widespread rumors adopted by parts of the Muslim community, such as suspicion that the vaccine contains pork or is being developed to sterilize Muslim girls. These rumors are based on inaccurate scientific information. For example, the sterilization myth was based on the vaccine containing trace amounts of estrogen, which they believed would have negative health impacts. However, the concentration of this hormone is too low in the vaccine to cause medical problems.

Yet the skepticism of the public towards these vaccination attempts is not unfounded historically. The chemical company Pfizer tested its meningitis antibiotic Trovan in remote communities in northern Nigeria in 1996, resulting in the death of 11 children. As a result, the Boko Haram, an Islamic militant group, has publicly opposed vaccinations in Nigeria.

Resistance among the public to vaccination has mounting consequences. Nigeria is presently the only country in the world for which the year-to-year incidence of polio is rising, but Pakistan could soon face a similar fate if its the vaccination program is not resumed.

Vaccination campaigns are trying to integrate the distribution of mosquito nets and vitamin supplements into their program in an attempt to regain favour with the general public; but a final eradication of Polio hot-spots in some of the poorest and most remote pockets of the developing world will prove no easy task.