by Centers for Disease Control (CDC)
The number of cases of Lyme disease, a tick-borne infection that can cause arthritis in humans, has reached a record level in the United States, federal health experts said on Thursday, Jan. 17.
The Centers for Disease Control and Prevention, which has launched education and disinfection programs to combat the emerging disease, said it suspected people were being exposed more often to ticks and that tick populations were becoming more dense and widely distributed.
"Both of these factors in addition to better reporting has probably led to the increased reported cases," said Stacie Marshall, an epidemiologist with the CDC's Division of Vector-Borne Infectious Diseases in Fort Collins, Colorado.
The Atlanta-based agency reported 17,730 cases in 2000, the latest year for which data was available. The figure represented an 8-percent increase from 1999 and was well above the average of 12,745 cases reported annually since 1991.
Lyme disease, which is spread to humans by tick bites, causes flu-like symptoms and a rash in its early stages. But, if untreated, it can spread to the brain, heart and joints, causing chronic arthritis and other symptoms.
It is usually treated with antibiotics.
EMERGED TWO DECADES AGO
More than 130,000 cases have been reported in the United States since the disease emerged in the early 1980s.
The CDC said most cases in 2000 were reported in Northeastern, Mid-Atlantic and North-central states. New York, Connecticut and New Jersey had the highest number of reported cases.
Connecticut, however, led the nation in incidence of Lyme disease, with 110.8 cases reported per 100,000 people. The CDC hopes to lower the incidence of the disease in states where it is endemic to 9.7 cases per 100,000 by 2010.
The agency is currently working on prevention projects with state and local officials to reduce tick populations in Connecticut, Massachusetts, New Jersey and New York, four states with high rates of the disease.
New strategies to prevent its spread include applying tick-killing devices to animals such as white-tailed deer and rodents. The CDC also said landscape-modification programs were being developed to reduce deer numbers around homes.
Most cases of Lyme disease arise from tick exposures in late spring and early summer. The CDC said children between the ages of 5 and 9 and adults between the ages 50 and 59 were at highest risk for contracting the disease.
The CDC noted that avoidance of tick-infested areas, use of insect repellents, prompt removal of attached ticks and appropriate vaccination had been shown to help prevent infection.
A vaccine licensed in 1998 is believed to be 76-percent effective in preventing the disease in people who received three doses. There is also a vaccine that can be given to all hunting, field trialing, and sporting dogs that frequent the outdoors.
Although some people claim that they became sick with arthritis-like symptoms after being vaccinated against Lyme disease, the CDC said it had seen no scientific basis to back up such reports.
The CDC says the vaccine should be considered for persons between the ages of 15 and 70 who live, work or engage in recreational activities in areas of higher or moderate risk of contracting the disease.