Sunday, January 6, 2013

Polio in Pakistan: challenges of and to eradication

In the past month, aid workers in Pakistan have been targeted by the Taliban. Six workers were killed in December and another seven were killed this past week in what is becoming a pattern of violence against polio vaccine workers in the country. According to the NPR articles, Pakistani militants have accused the vaccine program of being a Western plot to sterilize Muslim children. The CIA's use of immunization workers to uncover the location of Osama bin Laden increased hostility to the campaign. In response to the December shootings, the UN withdrew from participating in Pakistan's vaccination program, citing safety.

Polio is high on the target list for disease eradication. Smallpox is the only infectious disease that the world has successfully eradicated, and since that success--the world-wide outpouring of effort that resulted in smallpox being banished to lab experiments--other NGOs and health groups continue to dangle the goal of eradication in order to gain support for their cause. Gates Foundation has targeted malaria. Carter Center targets trachoma and guinea worm. Rockefeller Institute took up hookworm. And Rotary International has taken up the cause of polio.

What exactly is polio? Polio, or poliomyelitis, is a virus that enters the mouth and nose through contact with infected mucus, phlegm or feces and breeds in the throat and intestinal tract. It becomes absorbed into the blood and lymph systems where it incubates from anywhere from 5-35 days (one to two weeks on average) before symptoms might show. Most people, however, never show any symptoms, but they can still transmit the disease. Of those who do have symptomatic polio, most will only show mild symptoms. These include what you might expect from almost any mild flu: fever, sore throat, headache, vomiting. These will generally pass in a few days.

The polio that inspires so much work and fear and images of crippled children is when the poliomyelitis affects the central nervous system (brain and spinal cord). From there, polio causes paralysis, resulting in a lifelong problems with mobility and social stigma. (Most commonly, this paralysis affects the legs, but a relatively small percentage will die from the.) However, fewer than 1% of people who contract polio suffer from paralysis. Clinical polio, while tragic, is only fatal when it paralyzes the respiratory system, which occurs in 5-10% of the paralysis cases.

In the late 1940s and early 1950s, polio crippled almost 35,000 people a year in the United States. After Jonas Salk discovered a vaccine, the response was immediate and swift. Pictures of little girls in metal braces and crutches flooded media, urging parents to get their children immunized. The campaign worked--the fear and panic that had plagued the American people had mobilized them in participating in a mass vaccine campaign, successfully eradicating polio from the US by 1979. (The last cases of polio were in isolated Amish communities.)

Jonas Salk discovered the vaccine most of the readers will be familiar with. Four shots in the arm or leg of inactivated polio vaccine (dead polio virus bodies). In countries such as the US, these shots are given at two months of age, four months, six to eighteen months, and a booster at 4-6 years of age, part of the standard set of immunizations which American children are often required to have before entering school.

Jonas Salk had a little-known competitor, however, an Albert Sabin, who worked at Cincinnati Children's Hospital. He developed another vaccine, which he viewed as superior. Unable to get support for it in the US, he went to the USSR during the Cold War and tested it there. Sabin's vaccine is oral, two drops in the mouth, and is what is used in most mass vaccination campaigns in developing countries such as Pakistan. It is simpler to use, and, because it doesn't require an injection, runs less risk of accidental infection from non-sterile conditions.

With the elimination of polio from the US, public health campaigns grabbed the narrative of "we have this immunity, let the rest of the world have it too" to fund the Polio Eradication Initiative, a twenty-year, six billion dollar project that has involved two million people, making it history's largest public health campaign. The progress has been incredible, with only Pakistan, Nigeria, and Afghanistan still reporting cases. However, the success is tenuous, with recent outbreaks in the DRC and Chad, and children being born every minute who need to be vaccinated to keep the disease in check.

We tend to conceive of polio vaccination as being a simple four part program. But in places like Pakistan and India, ten or more doses of the vaccine spaced a month apart are required to confer immunity on a child. Poliomyelitis thrives in warm places with high population densities and poor sanitation--in other words, India and Pakistan. Svea Closser, author of the book, Chasing Polio in Pakistan: Why the World's Largest Public Health May Fail, writes:

"In 2006, surveillance data showed that in 93% of districts in Pakistan, the median number of OPV [the oral vaccine] doses that children under five had received was more than 7; it was more than three in 99 percent of districts. Put simply, if immunity to polio required, as in the United States, only three doses of vaccine, poliovirus would have already been eliminated in Pakistan."

To get the ten or more doses into every child is an incredible feat, with a lot of challenges. Next week, I draw on Svea Closser's ethnography to examine the challenges and the assumptions of polio eradication, and I'll speak some public health heresy and ask, Is it worth it?


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