Which manifestation is associated with a central nervous system infection in an infant?

Bulging fontanel is a key manifestation that can indicate increased intracranial pressure and potentially a central nervous system infection in infants. In infants, the fontanels, or soft spots on the skull, remain open to accommodate the rapidly growing brain. When there is swelling or increased pressure within the skull—often due to infection—inflation of the fontanels can occur, resulting in a bulging appearance.

While high fever, rash on the body, and lethargy can also be symptoms related to infections, they are not as specifically linked to central nervous system infections as bulging fontanel. High fever may be present in a variety of infections, lethargy is a non-specific symptom seen in many conditions, and a rash might suggest a different underlying issues, such as viral infections, rather than being directly related to a CNS infection. Therefore, bulging fontanel serves as a more specific indicator of potential complications affecting the central nervous system in infants, making it a critical symptom to assess in such contexts.