It’s human nature to wipe a threat from our minds when we no longer see evidence of it. One simple reason: it’s difficult to worry about a disease if it rarely appears as a daily reminder. The scars of smallpox on the face of a child. A neighbor’s pronounced limp from a childhood battle with polio. In wealthier nations, these daily reminders are rare or they no longer exist.
But the absence of daily reminders doesn’t mean a disease is gone. In the case of polio, it’s quite the contrary.
Many cases are “silent,” meaning people can carry the virus asymptomatically without exhibiting clinical signs of polio. Because of this, the infection can remain within a population for years, spreading through feces and lurking in the water and sewage. Hospitals may not notice an increase in polio cases, and by the time the first case of paralysis occurs, an area could be grappling with a full-on epidemic.
This is the insidious nature of the disease, hiding away as it waits for an opportunity to wreak havoc on populations.
PATH has a strategy to find, fight, and eliminate poliovirus from the world… and we’ve already begun.
Fighting polio with immunization and vigilance
In conversation, Kutub Mahmood leans forward with a sense of urgency and gets visibly excited about the prospects of eliminating polio. Kutub heads up the polio vaccine development project at PATH, working on vaccine development, scale-up, and new inactivated polio vaccine candidates. These efforts expand vaccine manufacturers’ ability to bring more vaccines to the global market and keep costs low for poor countries.
“The most critical thing we need to do,” says Kutub, “is aggressively reach out to the unimmunized and under-immunized populations in these countries with multiple vaccination campaigns.”
But it’s not just his work in vaccine development that keeps Kutub positive.
“Along with immunization, we have more tools available than ever before. PATH is developing methods for rapid and highly sensitive detection of poliovirus in contaminated water and sewage. Technologies like GPS and cell phones assist with efforts to eliminate polio in the hard places.” He adds that alliances with partner organizations put global efforts to eliminate the disease within reach.
Polio field detectives
David Boyle’s job is to reduce risk. And when it comes to finding out if poliovirus is present, the senior research scientist in PATH’s Diagnostics Program is always asking “Is it no longer here or are we just not seeing it?”
“Instead of waiting for cases to appear,” says David, “our approach is more aggressive, we look for the early warning signals that tell if the virus is present in the environment. It’s crucial to identify the poliovirus before it has a chance to sicken a population.”
And that means looking in sewage. The search for polio can be dirty, it can be dangerous, but it’s highly vital work.
Battling polio in a war zone
When we eliminate polio across continents, such as Africa, it brings us one step closer to full eradication.
And yet, pockets of the disease are still observed in Afghanistan and Pakistan. The work is dangerous in these countries, compounded by conflicts that interfere with routine immunization, disease surveillance, and tracking.
In countries such as these, we need new tools to identify where the poliovirus is still lurking.
In Pakistan, PATH and the University of Washington (UW) School of Public Health are piloting new methods for identifying the poliovirus in contaminated water and sewage. Recently, nearly 30 Pakistani polio program staff were trained to collect samples of wastewater with a new device developed by the UW in collaboration with PATH. These samples capture poliovirus onto filters that are then shipped to labs for testing.
“Surveillance workers will be using the new sampling tool for a study that is planned to start this month,” says David. “For most of this year, we’ll be intensifying efforts to detect poliovirus across the country.” The plan is to take samples from the sewage of 10 cities each month, a substantial effort that will result in dozens of sample sets.
This ongoing work at PATH will go a long way to ensure such detection methods are low-cost and available in poor countries.
As we near the reality of a polio-free world, vaccination efforts must be ramped up in concert with efforts to hunt the virus down where it still lives. We need to continue global surveillance long after it looks as if the battle has been won. Effective tools will help confirm that the poliovirus has been eradicated at the global scale. Then, and only then, we’ll know the world is free of polio.