August 15, 2009

Polio On The Rise In Nigeria

Polio is spreading in Nigeria and health officials say that the vaccine used to fight it has caused it, in some cases.

The World Health Organization (WHO) issued a warning in July that this vaccine-spread virus might extend beyond Africa.  So far there have been 124 Nigerian children that have become paralyzed this year from the disease, which is about twice those afflicted in 2008.

Polio is a dreaded paralyzing disease that has been stamped out in the industrial world.

This problem is just the latest challenge to global health authorities trying to convince wary citizens that vaccines can save them from the dreaded disease. 
Myths have abounded for years about the viruses, with some saying that the Western world's plan to sterilize Africans or give them AIDS was through vaccines. The sad polio reality fuels misguided fear and also underscores the challenges authorities face using a flawed medicine.

Nigeria, along with other poor nations, uses an oral polio vaccine because it is cheaper, easier, and protects entire communities.

However, it is made from a live polio virus that carries a small risk of causing polio for every million or so doses given.  In rare instances, the virus in the vaccine mutates into deadlier versions that ignite new outbreaks.

The vaccine that is used in the U.S. and other rich countries is in the form of a shot, which uses a killed virus that cannot cause polio.
In 2007, health experts said that amid Nigeria's ongoing outbreak of wild polio viruses, 69 children had been paralyzed in new outbreaks caused by the mutation of a vaccine's virus.

The WHO said back then that the outbreak would swiftly be taken care of, yet two years later the cases continue to build. 

Officials are worried that the polio epidemics in India and Africa will not be put to an end this year, after missing several earlier deadlines. 

"It's very disturbing," said Dr. Bruce Aylward, who heads the polio department at the World Health Organization.

The number of polio cases so far this year caused by the vaccine has doubled, leaving 124 children paralyzed.  In 2008, 62 children were paralyzed out of the 42 million children that were vaccinated.

Nigerian leaders suspended the vaccine in 2003, saying that it would sterilize their children and infect them with HIV.  Nigeria exported polio to about two-dozen countries worldwide, making it as far away as Indonesia.

In 2004, vaccinations were resumed after tests showed the vaccine was not contaminated with estrogen, anti-fertility agents or HIV.

Experts have speculated that epidemics unleashed by a vaccine's mutated virus would not last since the vaccine only contains a weakened strain of the virus.  However, experts now say that once viruses from vaccines start circulating, they become just as dangerous as wild viruses.

"The only difference is that this virus was originally in a vaccine vial," said Olen Kew, a virologist at the U.S. Centers for Disease Control and Prevention.

Children that have been vaccinated pass the virus into water supply through urine and feces.  Children that then play in or drink that water pick up the vaccine's virus, which gives them some protection against polio.

However, in rare instances the viruses pass through unimmunized children and mutates into a strain dangerous enough to ignite new outbreaks, particularly if immunization rates in the rest of the population are low.

Kew said a genetic analysis shows that mutated viruses from the vaccine have caused at least seven outbreaks in Nigeria.

Although Nigeria's coverage rates have improved, 15 percent of children in the north have not yet been vaccinated against polio.  Officials need to reach 95 percent of the population to eradicate the disease.

Experts say that Nigeria's vaccine-linked outbreak underlines the need to stop using the oral polio vaccine as soon as possible because it creates the epidemics it was designed to stop.  WHO is researching other vaccines that might work better.

WHO and U.S. CDC officials say the oral vaccine is the best available tool to eradicate polio and that when inoculation rates are nearly 100 percent it works normal.

"Nigeria is almost a case study in what happens when you don't follow the recommendations," Kew said.

Officials have slashed the disease's incidence by over 99 percent since WHO and partners began attempts to rid the world of polio in 1988.

However, a number of deadlines have been missed and the numbers of cases have been at a virtual standstill since 2000. 

"Eradication is a gamble," said Scott Barrett, an economist at Columbia University who has studied polio policies. "It's all or nothing ... and there is a very real risk this whole thing may fall apart."

Polio still exists in Afghanistan, Pakistan, India, Chad, Angola and Sudan.

Aylward said Nigeria's situation was another unwelcome hurdle, but eradication is possible.

"We still have a shot," he said. "We're throwing everything at it including the kitchen sink."


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