WASHINGTON – Confirmed cases of Lyme disease in Maryland increased more than threefold in the 1990s, giving the state the fifth-highest number of cases in the nation by 1999, according to the Centers for Disease Control and Prevention.
And Maryland health official said cases may increase again this summer, when relatively warm and wet weather conditions could lead to a “bumper crop” of the ticks that carry the disease.
The CDC this week said Lyme disease cases in Maryland grew from 238 in 1990 to 899 in 1999, the last year for which statistics were reported. Maryland’s cases increased 36 percent from 1998 to 1999, the report said, even as cases nationwide decreased slightly.
Most Maryland cases were reported in central and northern counties, with lower incidence rates in Western Maryland and the Lower Shore. Anne Arundel County had the most cases in 1999 with 115, followed by Harford with 90 and Howard with 89.
Officials attributed the increase to several factors, including growing numbers of deer, which carry the ticks that spread the disease, and a greater number of people living and playing near woods and grassy areas where the ticks are.
Maryland’s deer population increased about 25 percent since 1990, to an estimated 250,000 today, said Paul Peditto, of the state Department of Natural Resources.
Another reason could be “the reporting factor,” said Karon Damewood, chief of zoonotic diseases at the state health department. She said doctors and patients have become more aware of Lyme disease in the past decade and, therefore, are more likely to report it.
Damewood said there may be an increase again this year.
“This is not a disease to be laughed at,” she said. “People need to take steps to protect themselves from any tick attachments.”
Although Lyme disease is not fatal like other tick-borne diseases such as ehrlichiosis and Rocky Mountain spotted fever, it can cause devastating arthritic, neurologic, and cardiovascular problems if not treated.
Symptoms of Lyme disease include a growing rash where the tick attached itself, fever, muscle pains and lethargy. It is treated with a regimen of antibiotics. Unlike other diseases, people do not develop immunity to it and can become infected repeatedly.
The ticks, which often are smaller than a sesame seed, attach themselves to humans for four to five days. Normally, they need to be attached for at least 36 hours before risk of infection, and the risk grows the longer the tick stays attached.
“That’s why we recommend that people make a daily tick check,” said David Weld, executive director of the American Lyme Disease Foundation.
He said the disease can be avoided by using repellents, wearing appropriate clothing, including long pants and shirts, and by getting a vaccine that has been available since 1998.
Lyme disease first was identified in Lyme, Conn. in 1975, and the CDC has tracked it since 1990. The vast majority of cases occurred in the Northeast and the Midwest. Nine states, including Maryland, account for 90 percent of the cases, the CDC said.
Lyme disease occurs primarily from May through September. There is no spraying for the ticks, so it’s ultimately an individual’s responsibility to stay alert, Weld said.
“Just make sure you keep your eyes open in another month or so,” he said.