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India's carefully targeted strategy holds lessons for other countries, and for other diseases, argues Priya Shetty.
India was once one of the world's worst polio hotspots — but through a determined eradication strategy it has now taken a major step towards being free of the disease. Last week, the WHO declared the country polio-free for a year, ahead of the 2013 deadline for global polio eradication.
But the good news is confined to India. Afghanistan, Nigeria and Pakistan, where wild poliovirus transmission is still active, have seen alarming rises in polio cases, while other countries continue to see high rates of transmission. This has prompted the WHO to draft a resolution, to be discussed at the World Health Assembly this May, declaring polio a public health emergency.
Polio-ridden countries must look closely at the lessons they can learn from India's strategy for eradicating the disease, which combined the development of a highly effective vaccine with thorough targeting of high-risk groups.
And India could go further: it also needs to examine whether elements of the public health strategy that worked for polio could also work for efforts to control other infectious diseases.
Secrets of success
One major factor in India's win against polio has been its constant tweaking of the oral polio vaccine (OPV).
Early versions of the vaccine, introduced in India by the early 1990s, were trivalent — they could protect against all three strains of the virus. But once the type 2 virus was eliminated in 1999, new vaccines were rolled out that targeted only type 1. This left people vulnerable to type 3, but in 2010 a bivalent vaccine against both types 1 and 3 made an enormous difference in cutting rates of the disease.
The next challenge was to vaccinate children at highest risk. But finding them wasn't easy. Large swathes of the population in two poor states where polio was most prevalent — Uttar Pradesh and Bihar — are migrant workers, often travelling hundreds of miles out of their states in search of work.
Locate the workers, and you locate the children — so India mobilised thousands of health staff to transit points such as bus and train stations, busy highways and migrant camps. In 2011 alone, 2.3 million vaccinators immunised 172 million children.
India's focus on tracking high-risk populations — and its innovative thinking on how they could be targeted — secured success for the polio campaign.
Exporting the strategy
While India's strategy has paid off, it needs to be vigilant: the persistence of the virus in neighbouring countries means it is still at risk of the virus crossing its borders.
In 2011, Pakistan alone had nearly a third of the world's 627 cases, up from 144 in the previous year. Afghanistan had 76 cases, up from 25 in 2010. A poliovirus originating in Pakistan was recently found in China, which had been polio-free for two decades.
While these polio-endemic countries have different socioeconomic and political circumstances, they share other conditions — overcrowded populations, poor sanitation and migrant workers — suggesting that they can learn from India's experience.
India has already sent health workers trained in managing polio programmes to its neighbours, and is set to send more.
Targeting the bigger killers
Eradicating polio is a key milestone for public health in India. But other diseases, such as malaria and tuberculosis, which kill thousands of people each year, are far bigger health problems.
Mobilising health workers can help make progress against these diseases, such as by targeting migrants in the successful polio campaign.
Migrant and rural populations are hard to reach in any country, not least in countries such as Afghanistan, India and Pakistan where transport links are poor, and health systems don't keep proper tabs on people.
These populations often become pockets of infection that can hold back efforts to control disease. As with polio, young children need to be given the TB vaccine as early as possible to prevent the bacterial infection.
For both TB and malaria, diagnosis often happens too late because access to healthcare is inadequate. Again, mobilising an army of health workers can make a difference. If infections are detected early, treatment can be started at once.
It would also help health systems monitor the spread of the diseases, quickly reporting on resurgences or spikes in transmission.
Reach for the stars
Such efforts must be part of a mix of strategies. Public awareness is crucial for the success of any public health programme — for its anti-polio campaign, India poured money into TV adverts featuring Bollywood's top stars pushing people to vaccinate their children against the disease.
Similar awareness campaigns to educate people about the use of bednets, for example, and the need to clear areas of stagnant water can also make a big difference to stopping malaria transmission.
So India mustn't rest on the laurels of its success in eliminating polio. Recent reports of tuberculosis strains that are resistant to all known drugs underline the growing risk from infectious diseases.
The country has shown that despite shortages of healthcare workers, it can pull out all the stops when it wants to. Its resolve must not end with polio.
Journalist Priya Shetty specialises in developing world issues including health, climate change and human rights. She writes a blog, Science Safari, on these issues. She has worked as an editor at New Scientist, The Lancet and SciDev.Net.