Lyme Disease Vaccine in the Works

There’s good news for travelers worried about the risk of Lyme disease, the bacterial infection transmitted by the bite of ticks and this year most prevalent in Pacific Coastal areas, especially Northern California, where winter hiking is popular. The number of cases appears to be declining nationwide. And two vaccines under development look promising.

From January to Nov. 8, this year, 9,040 cases of Lyme disease were reported in the United States, according to the Centers for Disease Control and Prevention, compared with 13,716 during the same months of 1996. (Actual cases are estimated by some experts at five to 10 times the number of reported cases.)

Two vaccines--ImuLyme and LYMErix--have proven effective in studies, according to researchers who presented their findings at a recent meeting of the Infectious Diseases Society of America.

Both ImuLyme, made by Pasteur Merieux Connaught, and LYMErix, made by SmithKline Beecham Pharmaceuticals, were found to be more effective in younger adults than in subjects over age 60 or 65. In clinical trials involving more than 20,000 subjects, half of whom got a vaccine and half a placebo, the vaccines proved to be 90% to 100% effective in younger people after three doses, according to research studies.

In the ImuLyme trial, the vaccine was only 75% effective in those age 60 and older after three doses. But after a booster dose 12 months later, effectiveness increased. It’s not known why the vaccines are less effective in older people.

Before the end of this year, Pasteur Merieux Connaught expects to apply for Food and Drug Administration approval to market the vaccine, said Len Lavenda, a company spokesman. SmithKline Beecham has already filed for FDA approval.

Neither would estimate how soon the vaccines might be on the market, but other experts predict one or both could be generally available by 1999. It is hoped that the vaccines will eventually be approved for children too.

Until the vaccines are available, public health officials emphasize that prevention and early detection are still the best strategies, along with knowing which locations are riskiest for contracting Lyme disease.

Areas currently considered most hazardous, according to the CDC, include Pacific Coastal areas, especially Northern California, along with Massachusetts, Connecticut, Rhode Island, New York, New Jersey, Pennsylvania, Maryland, Delaware, Wisconsin and Minnesota. (In California, the number of cases reported from January through Nov. 8, was 155, up from 57 during the same period last year.)

Travelers destined for high-risk areas should wear long pants, a long-sleeved shirt and/or jacket, a hat and gloves. Tuck pants into socks or boots. Taping the area where pants and socks meet can help prevent ticks from crawling under clothing.

Walk in the center of trails to avoid hanging grass and brush, where ticks may be common. Spray tick repellent on clothing. Use insect repellents on exposed skin.

Check for ticks two times a day, paying particular attention to the neck and scalp. Wash and dry clothing at high temperatures if it is worn outdoors in areas infested with ticks.

Ticks that spread Lyme disease are much smaller than the more common dog tick, according to the CDC. In the West, the Western black-legged tick transmits the disease; in the Northwest and North Central areas, deer ticks are the carriers.

If a tick is found under the skin, use tweezers to grasp it as close to the skin as possible and pull it out. Do not use petroleum jelly over the tick or a burning match near the skin to draw it out. The match could actually cause the tick to release the Lyme disease bacteria.

Removal of a tick within 24 hours lessens the risk of getting Lyme disease, according to the CDC. Place the extracted tick in a bag or container, if possible, to help aid in its identification.

If a tick bite goes unnoticed, travelers should be alert to the usual first symptoms of Lyme disease. Often, a large, red skin rash appears around the bitten area, sometimes accompanied by flu-like fever or aching. This flat, circular, bull’s-eye rash usually occurs three to 30 days after the bite. But sometimes a skin rash is an allergic reaction to the bite, not a sign of Lyme disease. A doctor should be consulted for a diagnosis, should a rash appear.

Prompt treatment with antibiotics (given orally, intravenously or intramuscularly), can cure Lyme disease completely, according to the CDC. A delay in treatment increases the risk of related problems, such as heart rhythm abnormalities, joint pain and nervous system disturbances. Death associated with Lyme disease is rare.

The diagnosis can be made by isolating the bacteria in a lab or measuring the levels of antibodies in the blood.

The blood tests, however, are not foolproof. “A negative test is about 99% correct,” said David Weld, executive director of the American Lyme Disease Foundation, a New York-based national organization devoted to education and research. A false positive result is more likely, he said, than a false negative.

Due partly to heightened awareness about Lyme disease since it was first discovered more than 20 years ago in Lyme, Conn., fewer than 1% of people develop chronic problems, according to Weld.

For more information, call the American Lyme Disease Foundation, (914) 277-6970 or the CDC’s toll-free voice and fax information system at (888) 232-3228.

The Healthy Traveler appears the second and fourth week of every month.