Hilary Duff revealed that her 16-month-old daughter Mae James Bair has hand, foot and mouth disease. Learn why the actress is feeling "so weird" after Mae's diagnosis.

Complications from Hand-Foot-and-Mouth Disease. ... While rare, an uncommon and serious form of coxsackievirus can make its way to the brain and cause more severe complications like: ...

Hand, foot and mouth disease is a highly contagious infection, most commonly caused by the coxsackie group of viruses. While highly contagious, most cases will be relatively mild.

While hand, foot and mouth disease in adults is rare, it can happen, according to the Cleveland Clinic. Hand, foot and mouth disease in children under 10 is far more common.

In rare cases, hand, foot and mouth disease can lead to serious complications like viral meningitis (swelling around the brain and spinal cord) and encephalitis (swelling of the brain).