New Englanders and others who live in areas plagued by Lyme disease have been eagerly anticipating the advent of a vaccine, hoping perhaps to be able enjoy the woods and marshes again without eternal vigilance.
Two vaccines are indeed on their way, but anyone who thinks they’ll put an end to Lyme disease anxiety is doomed to disappointment.
Several weeks ago, an FDA advisory panel recommended approval of a vaccine made by SmithKline Beecham. Given as a series of three shots over a year, it was 79 percent effective at preventing Lyme disease in tests involving10,936 people aged 15 to 70. The FDA isn’t bound by the panel’s vote, but approval is considered likely.
Another company, Pasteur Merieux Connaught, is expected to submit a similar vaccine with comparable efficacy — tested in 10,305 people aged 18 to 92– to the FDA by this fall.
It’s wonderful, of course, to have “any new tools of prevention,” as Dr.David Dennis, coordinator of the Lyme disease program at the federal Centers for Disease Control and Prevention, puts it.
And in areas where Lyme disease is endemic, including many parts of New England, a vaccine will “make a real difference,” agrees Dr. Allen Steere, chief of rheumatology and immunology at New England Medical Center.
But even when the vaccines become available — and SmithKline’s could be out in a few months — you won’t be able to ramble freely in the boonies if you really want to avoid Lyme disease, which strikes 12,000 to 16,000 Americans a year.
For one thing, the studies so far have tested the SmithKline vaccine in people between 15 and 70 and the Connaught vaccine in people 18 to 92.Until research in children is completed, it’s not clear how well the vaccines will work in these groups. Nor is it clear whether people with certain diseases, including rheumatoid arthritis, should get the vaccines.
Also, since the vaccine doesn’t kill the tick itself — just the bacterium
inside it — you have to watch out for ticks anyway, because the ticks that spread Lyme also carry other diseases like babesiosis and ehrlichiosis.
It’s important to remember that it takes three shots given over a year’s span to get adequate protection. The SmithKline vaccine is only 50 percent effective after two shots. This means you have to start shots in advance; even if the vaccine is approved soon, you’d have time for only two shots by next summer.
And because of the way the vaccines work, the protection wears off fast, which means you’ll need shots every year. What happens is that the vaccines stimulate your immune system to make antibodies to a protein on the surface of the bacterium (Borrelia burgdorferi), which lives in the tick’s gut.When the tick takes a drink of your blood, it sucks in these antibodies, which then kill the bacteria inside the tick before they get in your blood stream. Your immune system never encounters the whole bacterium, which would give longer lasting immunity, so the immunity gets weaker with time.[CORRECTION – DATE: Tuesday, June 23, 1998: CLARIFICATION: A description in yesterday’s Health Sense column in the Health/Science section on how a Lyme disease vaccine works was incomplete. It should have said that even with the vaccine, people should remain vigilant because the antibodies stimulated by the vaccine don’t act on the tick itself — just the bacterium inside it, and
the tick could be carrying other diseases.
If, despite vaccination, a bacterium does enter your body, it substitutes another protein on its surface, against which the vaccine would not work.So if the first line of defense fails, you may still get infected.
Some doctors also worry that in people who already have a chronic form of Lyme disease, getting vaccinated might make things worse. “I would be extremely cautious about [vaccinating] anyone who thinks they had Lyme disease,” says Dr. Sam Donta, a specialist at Boston Medical Center and the Boston Veterans Affairs Medical Center.
But it’s not always easy to tell who’s been infected, because some people do not have obvious symptoms. In fact, Lyme disease is both often-missed and overreported. If you fail to notice the rash that follows within a few days of a bite from an infected tick, the symptoms that arise in the next few weeks — fever, chills, headache and fatigue — might be mistaken for something else.
In other words, even if you decide to be vaccinated — which makes sense if you live in an endemic area, despite the shortcomings — you will still need to take precautions against ticks, says Dr. Bela Matyas, medical director of epidemiology at the state Public Health Department.
The bottom line is that “70 percent of people contract Lyme disease in their own backyard,” says David Weld, executive director of the American Lyme Disease Foundation in Somers, N.Y.
That means that you’ll have to stay vigilant — all summer long.
SIDEBAR
With Lyme disease, prevention is the key
A mild winter and a wet spring mean this will be a banner year for ticks, and the rate of new Lyme disease cases is already double last year’s.
Here’s how to protect yourself:
- Learn to look for the deer tick, Ixodes scapularis, on your skin or clothing after walking in fields or woods. The tick is most likely to bite in the nymph stage, when it’s a dark speck the size of a poppy seed.
- If you can’t avoid areas where ticks thrive — woods, marshy areas, high grass, and bush — wear long-sleeved shirts, long pants tucked into socks, and closed-toe shoes. Light colors make it easier to spot ticks on your clothes.
- Spray clothes with insect repellant. Permethrin, the most effective, kills ticks on contact, but it’s very irritating, so don’t get it on your skin.
- Standard repellants for use on skin contain DEET (diethyltoluamide) and are also effective. High dose DEET may cause nerve damage in rare cases, and more often can cause allergic reactions. Avoid concentrations higher than 30-35 percent for adults; 10-15 percent for children. Don’t use it on your face and wash your hands so it doesn’t get into your eyes if you rub them. And don’t use it on kids under a year old.
- When you get home from a tick-infested area, shower or bathe and check yourself and your children carefully for ticks.
- Remove ticks with tweezers within 24-48 hours. Grab the tick as close to the skin as possible.
- If pets have been in tick-infested areas, check them, too, as well as areas where they sit or lie.
- If you become infected, call your doctor; antibiotics are effective, especially if given early.
For more information, contact:
Lyme Disease Foundation hotline 1-800-886-LYME (1-800-886-5963) or 860-525-2000.
American Lyme Disease Foundation, Inc., 914-277-6970.
(Web site: www.aldf.com).