Area health officials warn that the most dangerous season for tick-borne diseases such as Rocky Mountain spotted fever and Lyme disease has arrived.

In the past two months, Maryland has reported 12 cases of the potentially deadly Rocky Mountain spotted fever, which starts with a rash on the hands and feet and is generally regarded as the most serious of the several diseases spread by infected ticks, according to Dr. Christina P. Lazar, chief of the state health department's division of communicable disease surveillance.

Maryland reported about 30 cases of the disease last year, a significant drop from the record 120 cases a decade ago, Lazar said.

In Virginia, the latest statewide report, through May, shows no case of the fever, said Leslie Branch, staff epidemiologist with the Virginia health department. But last year, he said, 51 cases were reported, eight in Northern Virginia. "We get most of our cases reported through the warmer months," Branch said.

The District of Columbia reported no cases last year or so far this year. "It's not a city disease," Lazar said, explaining that ticks are more prevalent in less developed and wooded areas.

Nationwide figures show that last year 750 people contracted the disease, which causes fever, muscle pains and chills, sometimes leading to kidney disorders and brain hemorrhage, said Dr. Daniel Fishbein of the federal Centers for Disease Control in Atlanta. Typically, less than 5 percent of the cases are fatal, Fishbein said.

"Deaths do occur, but not often," Fishbein said, as long as those who are bitten by ticks and develop preliminary symptoms are treated promptly.

Health officials recommend that people inspect themselves and their pets for ticks after being outside, keep their lawns mowed to prevent the insects from colonizing, and use insect repellent. "If you don't get exposed, you don't get it," Lazar said.

Children are especially at risk because they often play in wooded areas, where ticks can be found in large numbers. "This year we have seen quite a few children with the disease" in Maryland, Lazar said.

Researchers this year discovered a new tick-borne disease called Ehrlichiosis, which occurs in most of the same states as Rocky Mountain spotted fever -- the mid-Atlantic states and parts of the Southwest -- and has similar symptoms. Fishbein said the CDC has warned state health departments of the disease and may some day require physicians to report cases of the disease to public health authorities.

Ticks also spread Lyme disease, which CDC specialists say has overtaken Rocky Mountain spotted fever as the most common tick-borne disorder in the United States. Symptoms include fatigue, fever, headaches, neurological complications and arthritis.

In most states, accurate statistics on Lyme disease are not available because doctors are not required to report it. "We're interested in all cases of Lyme disease even though it's not reportable by law," Branch said.