Final answer:
The most common cause of an abdominal mass in infants includes congenital conditions, with possible symptoms like enlarged spleen. Schistosomiasis can cause abdominal swelling due to liver and blood vessel damage. Preventable infectious diseases are a major cause of death in children under five in low-income countries.
Step-by-step explanation:
The most common cause of an abdominal mass in infants is typically related to congenital conditions, such as abdominal organ enlargement, digestive tract blockages, or cysts. For instance, in the scenario presented, the swelling and tenderness over the spleen suggests an enlarged spleen, which can be due to various conditions including infections, liver disease, or hematologic disorders. In some regions, schistosomiasis is a significant health concern, with symptoms that may include abdominal swelling due to liver and blood vessel damage. While schistosomiasis can cause such symptoms, it is important to consider that the most frequent cause of death for children under five in low-income countries, according to the World Health Organization, is often linked to preventable infectious diseases, malnutrition, and complications during birth.