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Abstract & Commentary
By Stan Deresinski, MD, FACP, Clinical Professor of Medicine, Stanford, Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center, is Editor for Infectious Disease Alert.
Source: CDC. Lyme disease — United States, 2003-2005. MMWR 2007; 56:573-576.
Synopsis: In the 10 states with the most cases, the annual incidence of Lyme disease was 29.2 per 100,000 population, but 3 counties (2 in New York, one in Massachusetts) reported rates in excess of 300 cases per 100,000.
Lyme disease is the most commonly reported vector-borne disease in the U.S., with approximately 20,000 new cases reported each year. Most cases occur in northeastern, mid-Atlantic, and north central states (see Map), with peak incidences among those ages 5 to 14 years and 45 to 54 years. CDC received 64,382 reports of Lyme disease from 46 states and the District of Colombia during 2003-2005, with 93% of cases occurring in 10 states. In those 10 states, the annual incidence was 29.2 per thousand population. However, 3 counties (Columbia and Dutchess counties in New York and Dukes county in Massachusetts) had rares in excess of 300 per 100,000 population. As expected, cases peaked during summer months, reflecting nymphal vector activity in May and June; fewer than 8% had disease onset during December through March. In the 10 states with the highest incidence of reported cases, 70% were reported to have erythema migraines, 30% had arthritis, 8% had facial palsy, 3% had radiculopathy, 2% had meningitis or encephalitis, and <1% had heart block.
The only way to prevent Lyme disease is to avoid tick bites and, failing that, to remove ticks within 24 hours after their attachment. The former can be achieved by avoiding, if possible, tick-infested areas and by using DEET-containing insect repellents (permethrin can be used on clothing). Wearing long pants, sleeves and socks and tucking pant legs into socks or boots (or taping them down) and shirts into pants is helpful. The latter can be achieved by performing self-examination (or examination by a close friend) for evidence of ticks after any potential exposure.
Surveillance Definition of Lyme Disease• Physician-diagnosed erythema migraines >5 cm in diameter OR
• At least one objective manifestation (e.g., arthritis, heart block, or a neurologic finding such as facial nerve palsy).