Re-Infection Rates and The Therapeutic Efficacy of Praziquantel Against Schistosoma Mansoni Among Selected Primary School Children in Jimma Town, Southwest Ethiopia

In the warm, slow-moving waters of many tropical regions, a microscopic threat waits just beneath the surface. It is a parasite called Schistosoma mansoni, a type of flatworm that spends part of its life cycle inside specific snails and the rest inside humans. When people come into contact with water contaminated by the parasite's free-swimming larvae, these tiny creatures can pierce the skin and travel through the body, eventually settling in the intestines. There, they lay eggs that cause inflammation, pain, and long-term damage to the liver and gut. Because the parasite relies on fresh water to move from snail to human, communities without safe water access or proper sanitation are most at risk. To fight this, health workers rely on a single, powerful medicine called praziquantel. It is the standard treatment used worldwide to clear these infections from children and adults alike. However, in places where the water remains contaminated, a treated person can easily get sick again. The critical question for public health is not just whether the medicine works, but how well it works over time and how quickly the infection returns in real-world settings.

In the town of Jimma, located in the southwest of Ethiopia, researchers set out to answer these questions among primary school children. The town is crisscrossed by rivers and streams, including the Awetu River, which flows right through the center of the community. Children here use these waterways for swimming, bathing, and washing clothes, creating frequent opportunities for the parasite to find new hosts. The study team, led by scientists from Jimma University and other local institutions, focused on five primary schools to see how well the standard treatment held up and how often the children became re-infected. They began by collecting stool samples from 521 students to check for the presence of parasite eggs. This initial screening revealed that nearly a quarter of the children, specifically 22.5 percent, were carrying the infection. Among those infected, the majority had a light burden of the parasite, though some carried moderate to heavy loads.

Once the infected children were identified, the researchers administered a single dose of praziquantel, carefully calculated at 40 milligrams for every kilogram of the child's body weight. The drug was given under direct supervision to ensure every child took the full dose. Three weeks later, the team returned to check the results. They found that the medicine was remarkably effective. Of the 92 children who were re-examined, 90 were completely free of the parasite, representing a cure rate of 97.8 percent. Furthermore, the number of eggs found in the stool of the remaining children dropped by 99.3 percent, a figure known as the egg reduction rate. This high level of success suggests that the drug is performing exactly as intended in this specific community, clearing the infection from the vast majority of those treated.

However, the story did not end with the first round of treatment. Because the water sources remained contaminated, the researchers wanted to know how quickly the children would get sick again. Six months after the initial treatment, the team returned to test the children who had been successfully cured. They found that the infection had returned in a small but measurable number of cases. Out of 79 children who were tested, five had become re-infected, resulting in a re-infection rate of 6.33 percent. While this rate is relatively low, it confirms that the parasite is still active in the environment and that a single dose of medicine, while highly effective at clearing current infections, does not provide long-term immunity against future exposure.

The study also looked closely at the behaviors that put children at risk. The data showed a clear pattern: boys were significantly more likely to be infected than girls. In fact, male students were more than three times as likely to carry the parasite. The researchers also identified a specific habit that increased the danger. Children who crossed rivers or streams barefoot were more than twice as likely to be infected compared to those who did not. This makes sense biologically, as the parasite's larvae can penetrate bare skin directly from the water. Other activities, such as swimming or bathing in the rivers, were also linked to infection in the initial analysis, but crossing the water without shoes emerged as the strongest independent predictor of risk.

The findings from Jimma offer a clear picture of the current battle against this parasite in the region. The infection level among the school children is considered moderate, falling within a range that requires continued attention but is not the highest seen in Ethiopia. The medicine used to treat the disease works exceptionally well, curing almost all children who take it. Yet, the low but persistent rate of re-infection highlights a fundamental challenge: as long as children continue to have direct contact with contaminated water, the cycle of infection will continue. The study confirms that while the drug is a powerful tool, it must be part of a broader strategy that includes understanding local behaviors, such as the habit of crossing rivers barefoot, to truly protect the health of the community.