CLINTON DIAGNOSED WITH PNEUMONIA

Nick Merrill, a spokesman for Clinton, said Clinton would remain at her home in Chappaqua, N.Y., to rest. A planned trip to California for events Monday and Tuesday was canceled, he said.

Pneumonia can be caused by viruses or bacteria, and it refers to an infection that gets into the lungs. Bacterial pneumonia is common, usually not serious and easily treated with antibiotics.

These mild bacterial infections can cause a cough and sometimes a mild fever.

People often feel well enough to go about their business, especially once they start taking antibiotics. And once they've been taking antibiotics for a day or so, they are unlikely to infect anyone else.

But the infection can take a toll, making patients prone to getting tired and dehydrated. And since people often don't realize they have an infection, they can go for days or weeks before they seek treatment — all time for the infection to wear them out even more.