What complication arises from untreated cases of measles in children?

Subacute sclerosing panencephalitis (SSPE) is a rare but serious complication that can occur in children who have measles. This condition typically arises years after the initial measles infection, often between 7 to 10 years later, and is a progressive neurological disorder that can lead to severe cognitive decline, seizures, and eventually death. SSPE is thought to result from a persistent infection of the central nervous system with the measles virus, which is not cleared effectively by the immune system.

In contrast, the other conditions listed in the options, such as acute respiratory distress syndrome, asthma development, and chronic obstructive pulmonary disease, are not direct complications associated with untreated measles. They may be related to other respiratory infections or chronic conditions but do not have the specific association with measles that SSPE does. This underscores the importance of prompt diagnosis and vaccination against measles to prevent complications, including this severe neurological outcome.