Environmental nuisance exposure mediates the relationship between abattoir proximity and household enteric dermatological morbidity: a GPS-anchored cross-sectional study in Bo and Kenema Cities, Sierra Leone

In many bustling cities across sub-Saharan Africa, the places where animals are slaughtered for food often sit right next to where people live. These facilities, known as abattoirs, are essential for feeding the population, but they generate significant waste. Without proper treatment, this waste—blood, gut contents, and wastewater—can seep into the ground, flow into open drains, and attract swarms of flies and rodents. The result is a constant assault on the senses for nearby residents: a pervasive smell, the noise of activity, and the risk of contaminated water. For years, public health officials and communities have operated on a simple assumption: the closer a home is to an abattoir, the sicker the people inside will be. It seemed logical that distance alone was the danger. However, this assumption has rarely been tested with precise measurements, and it has not been clear whether the sickness comes from the physical location itself or from the specific environmental mess that location creates. Understanding the difference is vital because it changes the solution entirely. If distance is the only problem, moving the facility might help. But if the problem is the waste and the pests, then cleaning up the mess is the only way to protect health, regardless of where the building stands.

A team of researchers from Njala University and the Ernest Bai Koroma University of Science and Technology set out to test these ideas in two of Sierra Leone's largest cities, Bo and Kenema. They wanted to know if the health problems reported by neighbors were actually caused by the smell, the flies, and the dirty water, or if simply living nearby was enough to make people sick. To find the answer, they did not rely on guesses or general impressions. Instead, they went door-to-door with a GPS-enabled questionnaire, visiting 950 adults living around confirmed, operating slaughterhouses. They mapped the exact location of every household and measured the straight-line distance to the nearest abattoir. At the same time, they asked residents to rate their daily exposure to five specific nuisances: how often they smelled bad odors, how frequently they saw flies or rodents, the level of noise, how often wastewater flooded their area, and whether their water source seemed contaminated. They combined these answers into a single score to represent the total "nuisance load" a household faced. They also asked about recent illnesses, specifically looking for stomach and skin infections, which are common in areas with poor sanitation, as well as malaria, a disease spread by mosquitoes.

The results painted a clear and surprising picture. The researchers found that as the distance from the abattoir increased, the nuisance score dropped steadily. People living closer reported more smells, more flies, and more flooding than those living further away. This confirmed that distance does determine how much environmental mess a household endures. However, when the researchers looked at who was actually sick, the story changed. They found that the likelihood of a household reporting stomach or skin illness was directly tied to the nuisance score, not the distance. A household with a high nuisance score was significantly more likely to be sick, regardless of whether they lived 50 meters or 200 meters from the slaughterhouse. Once the researchers accounted for the smell, the flies, and the waste, the physical distance itself no longer mattered. The data showed that the abattoir's proximity only harmed health because it determined the intensity of the environmental nuisance. In statistical terms, the nuisance exposure completely explained the link between living near the facility and getting sick.

To ensure this finding was not just a coincidence or a result of poverty affecting both the location of homes and the health of residents, the researchers used a clever check. They looked at malaria, a disease that is also common in the region but is spread by mosquitoes in a different way than the stomach and skin infections. If the problem were simply that poorer, sicker people lived near the abattoirs, then malaria rates should have been high near the facility as well. Instead, the opposite happened. The further away people lived from the abattoir, the more likely they were to report malaria. This opposite pattern suggested that the high rates of stomach and skin illness near the slaughterhouses were not caused by general poverty or poor living conditions, but were specifically linked to the waste and pests coming from the abattoir. The study concluded that the health burden in these cities is driven by the measurable load of environmental nuisance rather than the physical distance alone.

The implications of this discovery are practical and direct. It suggests that simply moving an abattoir further away from a city might not solve the health crisis if the waste management and sanitation practices remain the same. The true driver of illness is the exposure to the waste and the pests it attracts. Therefore, the most effective way to protect public health is to focus on reducing that exposure. This means improving how the waste is handled, ensuring wastewater is contained and treated, collecting garbage daily, and controlling the populations of flies and rodents. By targeting the nuisance itself, communities can lower the risk of illness for everyone, whether they live right next door or a few blocks away. The study, conducted in July 2026, provides a clear roadmap for policymakers: fix the mess, and the health of the neighborhood will follow.