Before a doctor ever diagnoses a child with acute flaccid paralysis, the culprit leaves definitive clues in the sewer. At the Noguchi Memorial Institute for Medical Research, we spin bottles of wastewater in the centrifuge, pH-balance, and look for these clues. Their presence signals the return of an enemy we once thought we had defeated.

For decades, the world has rallied around the dream of eradication, the triumphant declaration that humanity has conquered this disease. The vaccines work. The numbers have tremendously reduced but what happens when the celebration fades and the virus does not? In Ghana, we are slowly learning a very bitter truth, and that eradication is not the end. The end is maintenance and this is desperately hard to fund.

Environmental Surveillance (ES) has proven to be one of the world’s most successful public health systems, working quietly in the background to bring us closer to maintenance. The clues identified by ES buy us the single most precious resource in an outbreak, time. Time to vaccinate, to alert, and to contain the spread. Far from this ideal, ES practice in West Africa is extremely handicapped.

The Noguchi Memorial Institute for Medical Research ES lab epitomizes these handicaps. The staff does remarkable work, but their effectiveness is hampered by the inadequate sewage systems in Ghana. Our ES sites operate in 14 polio surveillance sites in just seven of the 16 regions. These surveillance sites are primarily in urban centers with above average sewage systems. Financial constraints, poor sanitation infrastructure or bad sewage networks and logistical hurdles mean that a good number of rural and peri-urban populations still remain unmonitored and are continuously vulnerable to polio outbreaks. In many of these districts, there is no sewage network at all, just open drains, septic tanks, and seasonal streams that carry both water and human waste. Ghana’s 2021 census showed that while 86 percent of households in Greater Accra have access to a toilet, only about 12 percent are connected to a piped sewer. In the northern regions, that figure often drops below 2 percent. How can the global health community expect us to run a 21st-century disease surveillance program on 19th-century infrastructure?

The global narrative of eradication often concludes with the last reported case. But in countries like Ghana, we have discovered that the absence of clinical cases does not mean the absence of viral circulation, it often means the virus has fallen through the cracks. The 90-95 percent asymptomatic rate of poliovirus infection means transmission can continue invisibly.

In 2022, vaccine-derived polioviruses (VDPV2) resurfaced across West Africa, including Ghana. This resurgence was not a failure of the vaccine but a failure of infrastructure. It is a great reminder that the final step of eradication depends not only on immunization, but on the nation’s sewage infrastructure.

As health care professionals and researchers we talk endlessly about complex vaccines, multi-million-dollar funding, and cutting-edge epidemiological modeling but rarely do we talk about the mundane reality of pipes, drains, sewages and the sanitation workers who make those systems real. I have to admit that I have been guilty of this too but my time at the ES lab has shifted my perspective. Sanitation plays an extremely important role in disease control.

This problem is not unique to Ghana alone. Across low- and-middle-income countries, the sustainability of disease surveillance is constrained by sanitation systems designed for a different era. The global polio eradication initiative has poured billions into vaccines and epidemiological capacity, but relatively little into the physical structures and networks that make environmental monitoring very feasible and efficient.

I often liken this to the human body. The sewage system, much like our blood vessels, is designed to carry life and it does so by circulating what sustains and removes what could harm. When those channels are blocked or broken, the tissues suffer from lack of oxygen (ischemia) and eventually die (necrosis). Similarly, in public health, when sewage stops flowing, data starves, which in turn negatively affects the preparedness for an outbreak.

As the world edges toward the final declaration of polio eradication, I fear we are preparing to celebrate too soon. We risk declaring victory and immediately walking away from the sustained, operational investment that truly locks it in. ES has outgrown its pilot phase. It is now a cornerstone of global health security. But without bold investments in sanitation infrastructure, seamless data systems, and African-led innovation tailored to communities without proper sewage networks, we as a country risk staying forever reactive by chasing outbreaks instead of anticipating them.

The next pathogen, whether it is a new poliovirus, a drug-resistant cholera strain, or something we do not yet have a name for, will also whisper first through the sewers. Therefore, if global health truly wants to win, it must stop looking at the last case and start listening to the foundations beneath our feet.

Shirley Sarah Dadson is a medical student in Ghana.