Malaria among children living in flood-prone villages in the Kasese District of Western Uganda: prevalence and risk factors from a cross-sectional study

In the highlands and river valleys of western Uganda, the rhythm of life is often dictated by the seasons. When the rains come, the rivers swell, and the land that was once dry becomes a temporary wetland. For the mosquito that carries malaria, these flooded areas are a banquet. The water creates perfect breeding grounds, leading to a surge in the insect population and, inevitably, a rise in the disease they transmit. Malaria remains a heavy burden in Uganda, causing significant illness and death, particularly among children. While health workers have long known that floods can trigger outbreaks, the specific patterns of who gets sick and where the danger is highest in these flood-prone communities have remained somewhat unclear. Understanding these patterns is crucial because it allows health officials to move beyond general warnings and instead target their limited resources—like insecticide-treated nets and clean water supplies—to the exact villages and households that need them most.

To map these hidden dangers, a team of researchers traveled to the Kasese District, an area known for its steep hills and rivers flowing from the Rwenzori Mountains. Between February and May 2025, they conducted a massive survey, visiting 160 small villages that had recently experienced flooding. They focused on children between the ages of two and twelve, a group particularly vulnerable to the disease. In total, nearly 8,000 children from over 3,700 households agreed to participate. The process was straightforward but thorough: researchers visited homes, explained the study in the local language, and collected a tiny drop of blood from each child's finger. They used a rapid diagnostic test, a simple tool that can quickly detect the presence of the malaria parasite in the blood, to see who was currently infected. Alongside the blood tests, the team gathered detailed information about the children's lives, including whether they slept under a mosquito net the previous night, how old the net was, where the family got its water, and the specific geography of their home, such as its altitude and distance from the river.

The results painted a clear picture of a disease that is still actively spreading, but with distinct hotspots and specific risk factors. Overall, about 3.3% of the children tested positive for malaria. While this number might seem low at first glance, the distribution of these cases was far from random. The researchers found that the risk was not evenly shared across the district. Two specific sub-counties, Kyarumba and Karusandara, emerged as significant hotspots, where infection rates were much higher than in neighboring areas. Geography played a major role; children living in low-lying areas, below 1,000 meters in elevation, were far more likely to be infected than those living at higher altitudes. In fact, the infection rate in the lowlands was nearly eight times higher than in the highlands. This makes sense, as the lower areas are where floodwaters linger, creating the stagnant pools where mosquitoes lay their eggs.

The study also revealed surprising details about who was getting sick. Contrary to the common assumption that the youngest children are always the most at risk, the data showed that children between the ages of five and twelve were more likely to test positive than those under five. The researchers suggest this might be because older children spend more time outside the home, perhaps fetching water or playing, which increases their exposure to mosquito bites. They also found that boys were slightly more likely to be infected than girls. Fever was a strong indicator; among the children who had a high temperature at the time of the visit, the infection rate jumped to over 10%, confirming that the test was catching active, symptomatic cases.

Household conditions proved to be just as important as geography. The study found that families who did not own a mosquito net were at a significantly higher risk of having an infected child compared to those who did. Even more telling was the behavior of the family: children who did not sleep under a net the night before the test were much more likely to be infected. Water sources also mattered deeply. Families that relied on surface water, such as rivers, lakes, or irrigation channels, or water from boreholes, had much higher rates of malaria than those with access to piped water. This suggests that the act of collecting water from these sources, or the proximity of the home to these water bodies, exposes families to more mosquitoes. Furthermore, larger households with more than six people were at greater risk, likely due to the difficulty of protecting everyone in a crowded space.

The researchers concluded that while malaria transmission is ongoing, it is highly concentrated in specific areas and driven by specific, modifiable behaviors. The clustering of cases in certain villages and the strong link to water sources and net usage suggest that broad, district-wide campaigns might be less effective than targeted interventions. By focusing on the hotspots in Kyarumba and Karusandara, ensuring that every household has a working net, and improving access to clean, piped water, health officials could significantly reduce the burden of disease. The study serves as a vital map for the future, showing that in the wake of floods, the path to protecting children lies not just in treating the sick, but in understanding the precise conditions that allow the disease to thrive.