Polio eradication strategy revised

Cash crisis forces mass vaccination campaign to focus.
14 May 2003

HELEN PILCHER

Polio vaccination campaigns will target the worst-affected countries. WHO

The World Health Organization is this week launching its revised campaign to rid the planet of polio. A programme of 51 intensive immunization campaigns will target 13 hotspots, including India, Egypt and Afghanistan. But some experts warn that the total eradication of polio is an unrealistic goal.

The new tactic re-routes dwindling funds, which were previously ploughed into another 80 countries, to areas where polio is rife or where people are deemed to be 'at risk' from re-infection from neighbouring countries.

"Concentrating our resources on strategic countries is crucial to root out and extinguish the remaining reservoirs of poliovirus," says Gro Harlem Brundtland, the WHO's director general. Routine, government-led vaccination plans will need to proceed as normal.

The revamped strategy is still hampered by the key concerns that surround polio eradication more generally, according to Donald Henderson of Johns Hopkins University in Baltimore, Maryland, who led the WHO's successful eradication of smallpox. "However, given the resources available, [the plan] is probably as good as can be put together," he says.

One problem is that even in areas that are now free of polio, long-term vaccination is needed to protect against the occasional immunized individuals who can carry and spread the disease. One man in Britain, for example, has excreted high levels of poliovirus for 20 years; indeed, 14 carriers have been found by chance since 1988.

What's more, the live, weakened form of poliovirus used for vaccination can mutate into a more aggressive, disease-causing form. This can be a problem in areas where vaccination levels are low and the virus can gain a foothold. In 2000, more than ten vaccine-derived polio cases were reported in the Dominican Republic and Haiti. This is further evidence, says Henderson, that "we need to plan to provide the polio vaccine indefinitely".

Poliomyelitis is a highly infectious disease that normally affects children under five and causes paralysis. The poliovirus thrives where sanitation is poor, and can be passed from unclean hand to mouth and by contaminated water. There is no cure - only vaccination can prevent the disease.

So the WHO, the US Centers for Disease Control and Prevention, Rotary International and UNICEF set up a global effort called the Polio Eradication Initiative. It hopes to rid the world of polio by the middle of 2004.

"But the persistent lack of financial resources could be the undoing of this campaign," warns Bruce Aylward, the initiative's coordinator. An extra US$275 million is needed to keep the programme running, he says.

Success story

Since 1988, mass immunization campaigns have reduced polio cases from an annual 350,000 in more than 125 countries, to just 1,919 in seven countries in 2002 - a global drop of 99%. More than 200 places are now polio-free.

Currently, 99% of the world's polio cases are concentrated in just three countries: India, Nigeria and Pakistan. Last year polio soared sixfold as India cut back on its immunization campaigns. Previously polio-free parts of the country succumbed once more.

The new tactics will shift 297 million vaccine doses and US$35 million to these countries, as well as to Egypt, Afghanistan, Niger, Somalia, Angola, Bangladesh, the Democratic Republic of Congo, Ethiopia, Nepal and the Sudan.

"The process has already started," says Aylward. Across India, health workers are going from house to house delivering two rounds of the oral vaccine to each of 180 million children. Half-a-million babies are born here each month, so a further four rounds will be given, for example, in and around the disease-ridden state of Uttar Pradesh later this year.