Before any physician diagnoses a child with acute flaccid paralysis, the offender leaves clear signs within the sewage. At the Noguchi Memorial Institute for Medical Research, we spin wastewater bottles in the centrifuge, adjust pH levels, and search for these indicators. Their existence signals the resurgence of an adversary we once believed we had vanquished.
For many years, the global community has united around the aspiration of eradication, the victorious pronouncement that humanity has triumphed over this affliction. The vaccines are effective. The statistics have significantly decreased, but what occurs when the festivities dim and the virus persists? In Ghana, we are gradually confronting a harsh reality: eradication is not the conclusion. The conclusion is ongoing maintenance, which is incredibly challenging to finance.
Environmental Surveillance (ES) has emerged as one of the globe’s most effective public health systems, operating subtly in the background to help us move closer to maintenance. The clues discovered by ES grant us the single most valuable commodity during an outbreak: time. Time to vaccinate, raise alarms, and limit the spread. Unfortunately, ES efforts in West Africa are significantly hindered.
The Noguchi Memorial Institute for Medical Research ES lab exemplifies these obstacles. The team produces exceptional results, yet their efficiency is stifled by Ghana’s inadequate sewage systems. Our ES operations take place at 14 polio surveillance sites across only seven of the 16 regions. These sites are mainly located in urban areas with above-average sewage systems. Financial limitations, subpar sanitation infrastructure or poor sewage networks, and logistical challenges mean many rural and peri-urban communities remain unmonitored and are perpetually at risk for polio outbreaks. In several of these districts, there is no sewage system whatsoever—only open drains, septic tanks, and seasonal streams that carry both water and human waste. Ghana’s 2021 census revealed that while 86 percent of households in Greater Accra have access to a toilet, merely around 12 percent are linked to a piped sewer. In the northern regions, this figure often falls below 2 percent. How can the global health community expect us to operate a 21st-century disease surveillance program using 19th-century infrastructure?
The worldwide narrative of eradication often concludes with the last reported case. However, in countries like Ghana, we have learned that the absence of clinical cases does not indicate a halt in viral circulation; it often means the virus has slipped through the cracks. The 90-95 percent asymptomatic rate of poliovirus infection allows transmission to proceed unseen.
In 2022, vaccine-derived polioviruses (VDPV2) reemerged throughout West Africa, including Ghana. This resurgence was not a failure of the vaccine but rather a breakdown in infrastructure. It serves as a significant reminder that the ultimate phase of eradication relies not solely on immunization, but on the nation’s sewage infrastructure.
As health professionals and researchers, we often engage in extensive discussions about intricate vaccines, multi-million-dollar funding, and state-of-the-art epidemiological modeling, yet we seldom address the everyday reality of pipes, drains, sewage systems, and the sanitation laborers who bring those systems into existence. I acknowledge my complicity in this oversight, but my experience in the ES lab has altered my viewpoint. Sanitation is crucial in controlling disease.
This issue is not exclusive to Ghana. Throughout low- and middle-income nations, the sustainability of disease surveillance is restricted by sanitation systems that were designed for another time. The global polio eradication initiative has invested billions in vaccines and epidemiological capabilities, but comparatively little in the physical infrastructure and networks that facilitate effective and efficient environmental monitoring.
I frequently compare this to the human body. The sewage system, akin to our blood vessels, is designed to sustain life by circulating essentials and removing potential hazards. When these channels are clogged or damaged, tissues suffer from a lack of oxygen (ischemia) and eventually perish (necrosis). Similarly, in public health, when sewage ceases to flow, data is deprived, adversely affecting outbreak preparedness.
As the world approaches the final declaration of polio eradication, I worry that we might be preparing to celebrate prematurely. We risk proclaiming victory only to immediately abandon the continuous, operational investment that secures it. ES has matured beyond its initial phase and is now a vital element of global health security. However, without courageous investments in sanitation infrastructure, integrated data systems, and African-led innovations tailored to communities lacking proper sewage networks, our nation risks remaining perpetually reactive, pursuing outbreaks rather than anticipating them.
The next pathogen, whether a new poliovirus, a drug-resistant cholera strain, or something yet to be identified, will also first make its presence known through the sewers. Thus, if global health genuinely aims to triumph, it must cease fixating on the last case and begin heeding the foundations beneath our feet.
Shirley Sarah Dad