"We would normally expect fewer than 10 cases in the first six months of the year, but in 2003 we have already had over 50 cases reported to the Amarillo Department of Public health," said Anne Denison, a registered nurse and the city's epidemiologist. "And, of course, what we're seeing is only the tip of the iceberg. Those are the cases that are actually reported to the health department."

Meningitis, viral or bacterial, is an infection of one of the layers of the tissue that surrounds the brain.

"The most important prevention message is hand washing, and that sometimes is a difficult message for people to receive, especially kids, and that's one of the reasons they're fairly efficient spreaders of the virus," Denison said.

Some people have the virus for a time without symptoms, Denison said, making the spread of the disease very difficult to control.

The virus "can be transmitted by the respiratory route or close contact," said Dr. James Boger, associate professor of pediatrics at Texas Tech School of Medicine.

Symptoms include severe headache, fever, stiff neck, body aches and eyes unusually sensitive to light, he said.

The same symptoms apply to bacterial meningitis, a much more serious and sometimes fatal form of the disease, and the only way to tell is with a spinal tap. Anyone with those symptoms should contact a physician quickly, Boger said.

Without performing a spinal tap, he said, doctors can't tell the difference between bacterial or viral infection.

"We don't take a chance," he said.