Minnesota Department of Health

News Release

May 9, 2003

Contact information

Lyme disease reported at record level in 2002 in Minnesota
Warmer weather brings seasonal warning from health officials

Reported cases of Lyme disease in Minnesota were at an all-time high in 2002, prompting state health officials today to warn Minnesotans to protect themselves when spending time in tick country.

Minnesota recorded 867 cases of the illness in 2002, compared with 461 cases in 2001 and 465 the previous year. Reports of the illness have been on the increase in recent years – only 283 cases were reported to the Minnesota Department of Health (MDH) as recently as 1999. Altogether, 4,337 cases of Lyme disease have been reported in Minnesota since 1983.

While MDH officials were not able to identify any single reason for the recent increase, they say the large number of Lyme cases underscores the importance of taking steps to protect yourself from tick-related diseases.

“This is the peak time of year for Lyme disease – the time when the risk of being exposed to the illness is greatest,” said David Neitzel, an epidemiologist with the Acute Disease Investigations and Control Section at MDH. “Eighty percent of Minnesotans who develop Lyme disease are exposed to the illness between mid-May and mid-July. Now that the weather is finally warming up, and people are starting to spend more time outdoors, it’s vitally important that they take appropriate precautions.”

According to Neitzel, it’s especially important to protect yourself if you spend time in areas of the state where the risk of exposure is highest – areas that provide habitat for Ixodes scapularis, better known as the "deer tick.”

Deer ticks carry the bacteria that cause Lyme disease, and they can also transmit two other serious illnesses as well – human granulocytic ehrlichiosis (HGE) and babesiosis. During 2002, both of these illnesses were also at record levels in Minnesota, with 149 cases of HGE and 7 cases of babesiosis reported.

Although deer ticks are typically active from April through October, the weeks between mid-May and mid-July represent the period of greatest activity for the nymph stage of Ixodes scapularis. The ticks are most likely to spread disease during the nymph stage, when they are very small and can feed without being detected.

Deer ticks are commonly found in wooded, brushy areas in 18 east-central and southeastern Minnesota counties. About 70 percent of the people who get Lyme disease in Minnesota are exposed to the illness in those 18 counties. Most of the other cases (23 percent of total) involve Minnesota residents who were exposed in western Wisconsin.

Protecting yourself from tick bites is still the first line of defense against tick-related illnesses, according to MDH officials. It’s also important to be alert for possible symptoms of these diseases if you’ve spent time in an area where you could have been exposed, so you can seek prompt medical attention. Although a vaccine was previously available for Lyme disease, the manufacturer has since withdrawn it from the market.

Deer ticks are smaller – and darker in color – than the common wood ticks that people may encounter this time of year. They also lack the wood tick’s characteristic white markings, and the back end of the female deer tick is reddish in appearance.

Areas of the state where you’re most likely to find deer ticks include Aitkin, Anoka, Cass, Chisago, Crow Wing, Isanti, Kanabec, Mille Lacs, Morrison, Pine and Washington counties; eastern Sherburne County; the southern portions of Carlton and St. Louis counties; the eastern portions of Houston, Wabasha and Winona counties, and the northern tip of Ramsey County. Much of the Twin Cities area lies outside this “high-risk” zone.

To protect yourself from tick bites, health officials suggest that you:

• Avoid possible tick habitat. Deer ticks are found in wooded, brushy areas. Unless you spend time in that kind of setting, simply being in a high-risk county won’t place you at risk.
• Use a good tick repellent. Products containing permethrin – which are used on clothing – are especially recommended for people who will be spending an extended period of time in possible tick habitat. Permethrin products are marketed under names like Permanone® and Duranon®, and are available in stores that sell camping and hunting supplies, and other outdoor gear. Standard DEET-based products are another option – but use a product containing no more than 30 percent DEET, and follow the manufacturer’s directions.
• Wear clothes that will help to shield you from ticks. Long-sleeved shirts and long pants are best. Tuck your pants into the top of your socks or boots, to create a “tick barrier.”
• Check frequently for ticks, and try to remove them promptly. Ticks actually have to bite you – and remain attached for at least a day to transmit Lyme disease. Some research suggests that HGE may be transmitted more quickly.
• Remove ticks slowly and gently, using a pair of tweezers or specially designed tick forceps. Avoid folk remedies like Vaseline, nail polish remover or burning matches – they are not a safe or effective way to remove ticks.

If you do develop a tick-related illness, you should see a physician right away, Neitzel emphasized. Early symptoms of Lyme disease typically include a characteristic “bulls-eye” rash, consisting of a reddened area, sometimes with a clear area in the middle, at the original site of the tick bite. The rash may expand in size to cover a very large area (usually greater than two inches), or even appear in several places on other parts of the body.

Not everyone develops the rash, however, so it’s also important to be alert for other symptoms of Lyme disease – fever, headache, chills, and pain in the muscles or joints – if you've spent time in “tick country” during the past month.

The symptoms of HGE and babesiosis do not include a rash, but they are otherwise similar to the symptoms of Lyme disease. Symptoms of HGE can include a sudden onset of fever of 102 degrees or more, chills, shaking, severe headache and muscle aches. Babesiosis is characterized by high fever, muscle aches, fatigue and loss of appetite. Some people can be infected by more than one disease at a time; 20 of the 149 HGE cases in 2002 also had evidence of Lyme disease.

More information about Lyme disease and other tick-borne diseases is available on the MDH Web site.

Also, for more information about:

• Signs and symptoms, diagnosis, treatment and prevention of Lyme disease, ehrlichiosis or babesiosis, call the Minnesota Department of Health at (612) 676-5414.
• Deer ticks in the Twin Cities Metropolitan Area, call the Metropolitan Mosquito Control District at (651) 645-9149.

-MDH-

For more information, contact:

Doug Schultz
MDH Communications
(651) 215-1303

David Neitzel
Acute disease investigations
(612) 676-5414

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