Community Seroprevalence of Anti-Schistosoma mansoni IgG Antibodies and Associated Factors in Baddan District, Ibb Governorate, Yemen
A cross-sectional study in Baddan District, Yemen, revealed a high seroprevalence (41.1%) of anti-Schistosoma mansoni IgG antibodies among residents, significantly associated with risk factors such as swimming, lack of footwear during water contact, open defecation near water sources, absence of household sanitation, and the presence of blood in stool.
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In the highlands of Yemen, where the air is cool and the land depends on the rhythm of the seasons, a silent struggle plays out between people and a microscopic parasite. This parasite, a flatworm known as Schistosoma mansoni, cannot survive on its own; it needs a host to grow and a specific type of freshwater snail to complete its life cycle. When people come into contact with water contaminated by the waste of infected individuals, tiny, free-swimming larvae released by these snails can penetrate human skin. Once inside, they mature into adult worms that live in the blood vessels, often causing chronic illness that damages the intestines and liver. For decades, health workers have tried to break this cycle through medicine and sanitation, but in many rural areas, the disease persists. Understanding exactly how and why people in these communities are getting infected is the key to stopping the spread, yet for many remote villages, the full picture of who is at risk and why remains unclear.
In the Al-Sanahi area of the Baddan District, researchers set out to map this hidden landscape of infection. They focused on a specific group of 90 residents, ranging from young children to adults, who live in a region defined by agriculture and frequent contact with streams and irrigation canals. Instead of looking for the worms themselves in stool samples, which can be difficult to find if the infection is light, the team looked for the body's memory of the battle. They collected blood samples and tested them for antibodies, which are proteins the immune system creates to fight off the parasite. Finding these antibodies is like finding footprints in the snow; it tells you the person has been exposed to the parasite, even if they are not currently sick or if the infection happened months or years ago. By pairing these blood tests with detailed interviews about daily life, the researchers aimed to uncover the specific habits and conditions that make infection more likely in this community.
The results revealed a significant level of exposure within the village. Nearly half of the people tested, specifically 41 percent, carried antibodies against the parasite, indicating that a large portion of the population has encountered the disease. The study did not find that men were infected more often than women, nor did it find that age alone was the deciding factor, though younger participants showed slightly higher rates of exposure. Instead, the danger was tied closely to how people interacted with their environment and the state of their homes. The most powerful predictors of infection were behaviors that brought people into direct, unprotected contact with water. Those who swam in local water sources were far more likely to have been exposed than those who did not. Similarly, walking barefoot or without protective shoes while in the water drastically increased the risk, as the skin is the entry point for the parasite's larvae.
Beyond individual choices, the study highlighted the critical role of sanitation and household conditions. People who lived in homes without proper toilets, or who defecated near water sources, faced a much higher risk of infection. This behavior allows the parasite's eggs to wash back into the water, infecting the snails and restarting the cycle. The data showed that having a toilet at home was a strong shield; those without one were significantly more likely to carry antibodies. Interestingly, the education level of a child's mother emerged as a protective factor. Children whose mothers had received formal schooling were less likely to be infected, suggesting that educated mothers may be better at teaching their families about safe water practices and hygiene. Conversely, the source of drinking water, whether from a pipe or a stream, did not appear to be a major factor in this specific group, pointing instead to contact with water for swimming, farming, or washing as the primary drivers of transmission.
The researchers also looked at the physical toll of the disease. They found a strong link between the presence of blood in a person's stool and the presence of antibodies, confirming that the infection is causing tangible harm to the intestines of those affected. While the study confirmed that exposure is widespread and linked to specific, preventable behaviors, the authors were careful to note what their work could not prove. Because the study was a snapshot in time rather than a long-term observation, it could not definitively prove that these behaviors caused the infections, only that they happened together. Furthermore, because the test detected antibodies that can linger for years, the high number of positive results might include people who were infected long ago and have since been treated, rather than only those currently carrying active worms.
Despite these limitations, the findings paint a clear picture of a community where the disease remains a persistent threat due to a combination of environmental exposure and sanitation challenges. The high rate of exposure suggests that the cycle of transmission is still active in Al-Sanahi. The study concludes that to truly control the disease in this area, efforts must go beyond just giving medicine. They must include improving access to toilets, encouraging the use of shoes in the water, and educating families—particularly mothers—about the risks of swimming in contaminated streams. Without addressing these daily realities, the parasite will continue to find its way into the blood of the next generation, keeping the cycle of infection alive in the highlands of Yemen.
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