Lyme Disease Worsens in Endemic States

ATLANTA, June 18 -- Borrelia burgdorferi are winning the Lyme disease war, at least in 10 endemic states that were targeted by Healthy People 2010 for a sharp reduction. Instead, with a vaccine no longer available, Lyme rates worsened, said the CDC.

By 2005, the number of tick-borne Lyme cases in the 10 states with high disease rates had already increased to about three times the Healthy People 2010 target, which had been established with the expectation of a vaccine, according to a CDC report.

The average annual incidence in these high-endemic states for the recent three-year period was 29.2 cases per 100,000 population, although the target of Healthy People 2010 was 9.7 new cases per 100,000 in the 10 states, researchers reported in the June 15 issue of the CDC's Morbidity and Mortality Weekly Report.

Somewhat diluting this, however, is a CDC perception that states have improved detection methods.

During the 2003-2005, 93% of the cases (59,770) in the country occurred in 10 endemic states, said the CDC. These were Connecticut, Delaware, Maryland, Massachusetts, Minnesota, New Jersey, New York, Pennsylvania, Rhode Island, and Wisconsin.

However, GlaxoSmithKline pulled Lymerix off the market on Feb. 26, 2002, citing poor sales. Others said the vaccine had unspecified adverse effects.

Lyme cases per 100,000 population in the 10 states were 29.1 in 2003, 26.8 in 2004, and advancing to 31.6 in 2005.

Annual rates for the 10 states in 2005 were Delaware (66.58), Connecticut (51.56), New Jersey (38.58) Massachusetts (36.51), Pennsylvania (34.49), New York (28.90), Wisconsin (26.35), Maryland (22.05), Minnesota (17.87), and Rhode Island (3.62).

With approximately 20,000 new cases reported each year, Lyme is the most common vector-borne disease in the U.S., the researchers said. From 2003 to 2005 the CDC received reports of 64,382 Lyme cases from 46 states and the District of Columbia.

From 2003 to 2005, three counties had annual rates above 300 cases per 100,000 population in all three years. They were Columbia and Dutchess counties in New York and Dukes County in Massachusetts.

Median age of the patients was 41, with most cases occurring among patients ages five to 14, and 45 to 54. Males accounted for 54% of the reported cases overall and 61% of the cases among children. According to the available records, 97% of the patients were white, 2% black, and less than 1% were other groups.

About 50% of the patients met the criteria for symptom evaluation. A history of erythema migrans was reported for 70%, arthritis for 30%, facial palsy for 8%, radiculopathy for 3%, meningitis or encephalitis for 2% and heart block for less than 1%.

Cases peak during summer months, reflecting transmission by nymphal vector ticks during May and June, the researchers said.

Findings in this report are subject to certain limitations. First, Lyme surveillance is complicated with both underreporting and over diagnosis of cases.

Second, differences in patient demographics, such as age and sex, among states with above- and below-average incidence suggest variation in diagnostic and reporting practices among states.

Finally, clinical information on symptoms was not verified independently and often was incomplete.

The researchers advised patients living in Lyme disease-endemic areas to reduce their infection risk by doing daily self-examination for ticks, by using insect repellents containing DEET (N, N-diethyl-m-toluamide), employing simple landscaping practices (cleaning brush and leaf litter, for example) that reduce tick populations in yards and play areas, and avoiding tick-infested areas.

For persons who are infected, prompt diagnosis and treatment are important to prevent serious illness and long-term complications, the researchers said.