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Lyme Disease—United States, 2000
Arch Dermatol. 2002;138:555-556.
LYME DISEASE (LD) is caused by the tickborne spirochete Borrelia burgdorferi sensu lato and is the most common vectorborne
disease in the United States. CDC initiated LD surveillance in 1982, and the
Council of State and Territorial Epidemiologists designated it a nationally
notifiable disease in 1991. This report summarizes the 17,730 cases of LD
reported to CDC during 2000, which indicates that more LD cases were reported
in 2000 than in any previous reporting year and that the reported incidence
of LD is greatest in the northeastern, mid-Atlantic, and north-central regions
of the United States. LD can be prevented by reducing tick populations, avoiding
tick-infested habitats, using repellents, promptly removing attached ticks,
and vaccination.
For surveillance purposes, LD is defined as the presence of a physician-diagnosed
erythema migrans (EM) rash  5 cm in diameter or at least one manifestation
of musculoskeletal, neurologic, or cardiovascular disease with laboratory
confirmation of B. burgdorferi infection.1 Incidence was calculated using 2000 population
data from the U.S. Census Bureau.
During 2000, a total of 17,730 LD cases (incidence [per 100 000
population]: 6.3 cases) were reported from 44 states and the District of Columbia,
an 8% increase over 1999 (16,273 cases) and a 5% increase over 1998 (16,801
cases) (Figure 1). As in previous years, most cases were reported from the
northeastern, mid-Atlantic, and north-central regions (Table 1). State incidence
was higher than the national incidence in Connecticut (110.8), Rhode Island
(64.4), New Jersey (29.2), New York (22.8), Delaware (21.3), Pennsylvania
(19.1), Massachusetts (18.2), Maryland (13.0), Wisconsin (11.8), Minnesota
(9.5), New Hampshire (6.8), and Vermont (6.6); these 12 states accounted for
16,877 (95%) of nationally reported cases. During 1999-2000, 24 states and
the District of Columbia reported increases in the number of cases, 19 reported
decreases, and seven reported no change. In 2000, no cases were reported in
six states (Colorado, Georgia, Hawaii, Montana, New Mexico, and South Dakota).
Based on data for 17,570 (99%) LD cases, 723 (23%) of 3,143 U.S. counties
reported at least one case; approximately 90% of the cases were reported from
124 counties (Figure 2). Reported incidence was >100 cases in 24 counties
in Connecticut, Maryland, Massachusetts, New Jersey, New York, Pennsylvania,
Rhode Island, and Wisconsin; the highest incidence (943) was reported in Columbia
County, New York.
Among 17,551 LD patients with age reported, distribution was bimodal
and the median age was 39 years (range: <1-98 years). The highest reported
incidence occurred among children aged 5-9 years (9.3) and adults aged 50-59
years (8.2). Among 17,663 patients with sex reported, 9,472 (53.6%) were males,
who had a higher incidence compared with females in all age groups. Among
12,977 (73.2%) patients with month of illness onset reported, 7,427 (57.2%)
occurred during June (27.3%) and July (29.9%); <5.8% occurred during January,
February, and December 2000.
Reported by:
State and District of Columbia health depts. S Marshall, MPH, E Hayes,
MD, D Dennis, MD, Div of Vector-borne Infectious Diseases, National Center
for Infectious Diseases, CDC.
Editorial Note:
During 1991-2000, the reported incidence of LD nearly doubled. Most
cases continued to occur in northeastern, mid-Atlantic, and north-central
states,2-3 and the largest
proportion of cases continued to be reported among persons aged 5-9 years
and 50-59 years, possibly as a result of greater exposure than other groups
to infected ticks, less frequent use of personal protective measures, differential
use of health-care services, and/or reporting bias. The large number of reported
LD cases during June and July reflects the seasonal peak of host-seeking activities
of infective nymphal-stage vector ticks during May and June in areas where
LD is endemic.4
The findings in this report are subject to at least three limitations.
First, because LD is reported through passive surveillance, LD is underreported,
and the distribution and demographics of reported cases could be biased. Second,
LD is underreported in areas where disease is endemic and might be overreported
in areas where disease is nonendemic. Third, not all LD patients present with
typical manifestations; other conditions might be confused with LD and laboratory
testing might be inaccurate.
LD can be prevented by reducing tick populations, avoiding tick-infested
areas, using repellents, promptly removing attached ticks, and vaccination.
Booster doses may be required, but the optimal schedule for this has not been
determined. A vaccine was licensed in 1998 that is 76% effective in preventing
LD among recipients of 3 doses.5 New strategies
for reducing tick vectors of LD include applying acaricides to the principal
animal hosts of Ixodes scapularis ticks (i.e., a
device for killing ticks on white-tailed deer and a bait box for killing ticks
on rodents)6 (CDC, unpublished data, 2001).
In 2001, community-based LD prevention projects were initiated in Connecticut,
Massachusetts, New Jersey, and New York. Through the application of integrated
prevention strategies in community-based programs, CDC and state health departments
hope to achieve the 2010 national health objective of reducing the incidence
of LD to 9.7 in states where LD is endemic (objective 14-8).
MMWR. 2002;51:29-31.
2 figures, 1 table omitted.
REFERENCES
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1. CDC. Case definitions for infectious conditions under public health surveillance. MMWR Recomm Rep. 1997;46(RR-10):1-55.
2. Orloski KA, Hayes EB, Campbell GL, Dennis DT. Surveillance for Lyme disease—United States. Mor Mortal Wkly Rep CDC Surveill Summ. 2000;49:1-11.
3. CDC. Lyme disease--United States, 1999. MMWR Morb Mortal Wkly Rep. 2001;50(10):181-185.
4. Dennis DT. Epidemiology, ecology, and prevention of Lyme disease. In: Rahn DW, Evans J, eds. Lyme Disease. Philadelphia,
Pennsylvania: American College of Physicians, 1998:7-34.
5. CDC. Recommendations for the use of Lyme disease vaccine: recommendations
of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 1999;48(RR-7):1-17, 21-25.
6. Pound JM, Miller JA, George JE, Lemeilleur CA. The "4-poster" passive topical treatment device to apply acaricide
for controlling ticks (Acari: Ixodidae) feeding on white-tailed deer. J Med Entomol. 2000;37:588-94.
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