Molecular identification, quantification and phylogeny of non-polio enteroviruses: A wastewater-based epidemiology from northeastern Nigeria

Viruses that infect the gut often travel through the water we use and the waste we discard. Among these are a large family of germs called enteroviruses. While many of these infections cause no symptoms or only a mild fever, some specific strains can lead to serious neurological problems, including a condition that causes sudden weakness in the limbs. Because these viruses shed into the environment long before a person might feel sick enough to visit a doctor, scientists have learned to look for them in sewage. This approach, known as wastewater-based epidemiology, acts like a wide net cast over a community, catching evidence of viral circulation that clinical hospitals might miss. It allows researchers to see not just if a virus is present, but how much of it is there and what genetic variations are moving through the population.

In a recent study focused on northeastern Nigeria, researchers turned this method toward a group of viruses called non-polio enteroviruses. These are related to the poliovirus but are distinct types that can still cause severe illness. The team collected sewage samples from six different states in the region, an area where security challenges and varying sanitation infrastructure make monitoring difficult. They processed four hundred samples, concentrating the liquid to find any viral particles hidden within. Using cell cultures that mimic human tissue, they grew the viruses to confirm their presence, then measured the amount of genetic material to determine how heavily the water was contaminated. Finally, they sequenced the genetic code of the viruses to identify exactly which types were circulating and how they were related to strains found elsewhere.

The investigation revealed that these viruses are widespread in the region's sewage. Overall, more than forty percent of the samples tested positive for non-polio enteroviruses. The contamination was not evenly distributed; one state, Gombe, showed the highest rate of detection, with more than half of its samples testing positive. This suggests that local conditions in that area, such as population density or sanitation access, may be driving higher levels of viral spread. The researchers also measured the quantity of virus in the water. They found significant differences in viral loads between the various states. One state, Borno, had the highest average amount of virus, while another, Taraba, showed levels similar to the others. In two other states, Yobe and Taraba, the differences in viral amounts between specific sampling sites were not statistically significant, indicating that the virus was present at relatively consistent levels across those locations.

Beyond simply counting the virus, the team looked at the genetic makeup of the strains they found. They identified a specific type known as Echovirus E19 in several locations. When they compared the genetic sequences of these viruses to a database of known strains, they found a striking connection. One sample from Borno State was genetically very similar to a strain that had been identified more than a decade ago in Ibadan, a city in southwestern Nigeria. This finding suggests that the virus has been moving across the country, likely carried by people traveling between regions or through environmental pathways. The presence of such diverse and high levels of these viruses in the sewage indicates that they are circulating actively within the community, even if they are not always showing up in hospital records.

The study highlights the value of looking at the environment to understand public health risks. By analyzing sewage, the researchers were able to map the presence of these viruses across a large, complex region and identify specific hotspots where the viral load is highest. The genetic links they discovered between distant parts of the country underscore the need for a coordinated national system to track these germs. Continuous monitoring of wastewater, combined with detailed genetic analysis, offers a powerful way to detect emerging strains early and understand how they move. This approach provides a clearer picture of the viral landscape than clinical surveillance alone, offering essential data to guide public health efforts and manage the risk of serious illness in Nigeria and similar settings.