Heading East? Guard Against Lyme Disease

Most savvy travelers take precautions when voyaging to distant lands, especially when their journeys take them to developing nations. These precautions are especially wise when traveling to countries or regions that have high rates of diseases that are rare elsewhere (for example, malaria and parasitic illnesses).

But foreign destinations are not the only places where these “endemic” diseases present a risk. In several regions of the United States, a potentially serious bacterial infection known as Lyme disease poses a problem. Lyme disease (which gets its name from a Connecticut town where many cases occurred) is caused by a bacteria named Borrelia, which is carried by ticks. Humans can be infected only if they are bitten by a tick that is carrying the bacteria.

About 80% of people who are infected with Borrelia bacteria develop an illness characterized by fever, headache, muscle aches, joint pain and fatigue. A rash also frequently develops at the site of the tick bite. The rash has a characteristic “bull’s-eye” pattern--a circular, reddened area surrounded by a ring of red. If the initial infection is not treated, some patients will develop more serious problems in subsequent months, including severe arthritis and neurological problems.

The particular ticks that spread Lyme disease live on the blood of deer, mice and birds, so the risk of human infection is high only where these animals are found--in forests and in residential areas adjacent to woods or overgrown brush. The overwhelming majority of Lyme disease cases in the United States occur in the Northeast, the mid-Atlantic states and the upper Midwest. A much smaller number of cases occurs in the West, including California.

Only 13 cases of Lyme disease are known to have occurred as a result of tick bites within Los Angeles County. (Other Southern California residents have been infected through tick bites that occurred elsewhere in the country.) Although the risk of Lyme disease is low locally, it is important for Southern Californians to take precautions when they are hiking through forest and brush areas or traveling to places in the United States where the problem is common.

The best way to prevent Lyme disease is by avoiding areas likely to be infested with ticks, especially during the spring and summer when young ticks are present and their biting activity is high. Ticks thrive on the ground in wooded areas and in residential areas where the brush is overgrown or leaf litter has built up. If you will be in such areas, it’s important to cover up skin that could come in contact with ticks, especially your legs (ticks cannot jump or fly). Wear long-sleeved shirts and long pants, and tuck your pants into your socks or boots to protect your ankles.

Wearing light colors makes it easier to spot any ticks that do get on your clothing, so you can remove them before they attach to your skin. You should also consider applying insect repellents, such as DEET, to your clothes and any exposed skin. Or you can apply a pesticide, such as permethrin (which kills ticks on contact), to your clothes. After every trip through “tick country,” inspect your clothing and all of your skin.

If you are bitten by a tick, it’s important to remove the insect as quickly as possible to prevent infection with Lyme disease. (The tick usually needs to be attached for at least 36 hours before infection occurs.) If a tick has attached itself to your skin, remove it immediately with fine tweezers. Grasp the tick as close to the skin as possible and simply pull its body away from the skin. Don’t be alarmed if part of the tick’s mouth remains in your skin, because the bacteria that cause Lyme disease are contained in the insect’s body. If any symptoms of Lyme develop after a tick bite--or even after you have been in a tick-infested region--talk to your doctor immediately about treatment.

If you are traveling to a part of the country where the risk of Lyme disease is high, consider another precaution: immunization. The National Advisory Committee on Immunization Practices recommends that people ages 15 to 70 (except pregnant women) consider getting a vaccination if they are traveling to such an area and anticipate frequent or prolonged exposure to ticks. Although the vaccine does not guarantee protection against Borrelia bacteria, it does reduce your risk; the vaccine is about 50% effective after two doses and 75% effective after three.

If you are planning to spend time in one of the regions where Lyme disease is prevalent, contact local health authorities ahead of time for information and advice.

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Dr. Jonathan Fielding is the director of public health and the health officer for the Los Angeles County Department of Health Services. Dr. Valerie Ulene is a specialist in preventive medicine. They can be reached at ourhealth@dhs.co.la.ca.us. Our Health runs the second and fourth Mondays.