AFP was first used as a surveillance tool in 1985 when the Pan American Health Organization decided to end polio in the Western Hemisphere. Polio is a difficult disease to diagnose; many other afflictions look a lot like it. So, instead of leaving it to doctors and ill-trained medical workers to spot its symptoms, a decision was made to collect stool from every case that looked like polio. Basically, every AFP case. WHO soon recommended the same strategy, and India followed suit in 1997.
But things didn’t go as expected. Since polio was the biggest cause of AFP in the nineties, the assumption was that the AFP burden would shrink as polio declined. The WHO even estimated the number it would drop to non-polio AFP cases for every 100,000 children under 15 years (NPAFP rate) ought to shrink to around 1-2 each year, it said.
Total AFP Cases
This happened in countries such as the US and Sri Lanka. But in India, AFP numbers rose. Between 2001 and 2011, for example, India’s NPAFP rate grew from 1.88 to 16.14. Total AFP cases, which include NPAFP as well as confirmed and suspected wild poliovirus infections, jumped from over 7,000 to 60,000 per year. And the numbers still haven’t fallen to WHO’s estimate. Even in 2018, polio-free India had an NPAFP rate of 9.73.
Polio experts have proposed several explanations for this spike. The most common one is that India has an exceptionally intensive AFP surveillance network—one of the best in the world. And around 2003, already struggling with a huge number of cases, India dialed its surveillance up a notch, counting even borderline cases as AFP. Further, it began increasing the number of centers that reported AFP cases—from over 20,000 in 2004 to over 35,000 in 2012. And some of the reporting sites weren’t hospitals at all, but even temples and quacks, where families often took stricken children.
The consequence of this was that a number of mild cases, and cases which weren’t even paralysis, were caught in the AFP net, some experts say. “Even a slight injury, which leads to 2-3 days of limping, gets reported by hospitals because surveillance is intense,” says Jagadish M Deshpande, who previously headed the Enterovirus Research Centre and worked on polio surveillance systems in India. This would mean that a number of AFP cases may not be paralysis at all.
National Polio Surveillance Project
Yet, there are other children who do become permanently disabled. And neither the National Polio Surveillance Project (NPSP), nor any other Indian agency has any idea of how many cases fall in this category. This is because of a blindspot in India’s AFP monitoring. “Once the sample is negative for polio, the story ends,” says Govindakarnavar Arunkumar, a virologist at the Manipal Centre for Virus Research in Karnataka. The negative samples are typically not investigated further by NPSP, although external researchers like Durga Rao have conducted occasional studies.
The patchy data that exists, however, suggests that a significant number of AFP cases end in permanent paralysis.
A critical blindspot
Over a decade ago, C Sathyamala, a researcher from Delhi’s Council for Social Development, sought information on the number of children with long-term symptoms under India’s Right to Information Act. She found that in 2006, NPSP had tracked some 2,043—around 18%—AFP cases in Uttar Pradesh. Out of these, 989 had residual paralysis and 244 died.
Based on this, Sathyamala argued in a letter to the Indian Journal of Medical Research that intensive surveillance systems couldn’t fully explain the high number of AFP cases in India.
Of course, the information received by Sathyamala pertains to UP alone; nothing is known about NPAFP elsewhere. This paucity of information even when NPSP collects samples from all paralysis cases is disturbing, says T Jacob John, a Vellore-based virologist known for his work on polio. “Doing AFP surveillance from the late 1990s, and not knowing the exact clinical diagnosis of every case even in 2019 is diagnostic of a paralyzed health management system,” he says.