With summer — and tick season — fast approaching, there’s a new weapon available to reduce your chances of catching Lyme disease: a vaccine called LYMErix, approved by the Food and Drug Administration late last year.
Now, the bad news. The vaccine isn’t approved for kids under 15 or people over 70. It protects about 80 percent of the people who get it, and that’s if you get three shots, which, according to current FDA licensing, must be taken over 12 months. If you get only two shots, a month apart, there’s only a 50 percent chance you’ll be protected. And no one knows how long the protection will last.
Moreover, even if the vaccine were 100 percent effective, you’d still have to take the usual precautions — wearing long sleeves and pants and using tick repellents and removing attached ticks — if you live, work or play in woodsy or marshy areas. That’s because ticks that carry Lyme can also infect you with babesiosis and erlichiosis, other tick-borne infections for which there are no vaccines.
But there’s a promising new wrinkle in all this. Last fall, the vaccine manufacturer, SmithKline Beecham, reported that it’s possible to compress the timetable for the three immunizations into six months or even two and still get the same degree of protection as with the year-long schedule.
The company is not pushing this timetable — yet — because it’s still in the process of seeking FDA approval for it. But since there’s justification for accelerating the shots, it’s worth talking to your doctor about it if you’re at high risk.
Lyme disease is a nasty, though rarely fatal, illness that is both often-missed and overreported. It strikes about 12,000 to 16,000 Americans a year, mostly in the Northeast, but also in the upper Midwest, Pacific Northwest and elsewhere.
It starts with a bite from the deer tick, Ixodes scapularis. If you get the ticks off your skin within 36 to 48 hours, you’re probably safe because it takes this long for the disease to be transmitted, says David Weld, executive director of the American Lyme Disease Foundation in Somers, N.Y.
The bite causes a rash that often looks like a “bull’s eye” and flu-like symptoms — fever, chills, headache and fatigue — as well as occasional facial weakness and heart disturbances. Some people may have chronic arthritis or neurologic problems even months or years later.
In fact, scientists from Boston reported this month at an international conference that they have found a neurotoxin made by the Lyme bacterium.
The toxin “may explain memory problems and why nerves get stimulated so that they fire off and you get pain, numbness or tingling,” says Dr. Sam Donta, the lead researcher and a Lyme disease specialist at Boston Medical Center and the Boston VA Medical Center.
‘The evidence is accumulating,” he says, “that this is a subtle, chronic infection, but we have a long way to go.”
If you catch Lyme disease quickly — while you still have the rash — antibiotics often work. But not always. New evidence also presented at the conference showed that even after receiving antibiotics, some dogs with Lyme disease still harbored the bacteria that causes it, Borrelia burdorferi.
Complicating the decision about whether to get vaccinated this year (other vaccines are in the pipeline for future seasons) is the fact that scientists are unsure as to whether this tick season will be worse than usual. Some say it will be, but much of this is guesswork is based on the complicated life cycle of ticks.
Adult ticks mate in the fall on the bodies of large mammals, chiefly deer.
No disease is transmitted at this point, but after feeding on deer blood, pregnant female ticks drop off and bury themselves in leaves. Each female lays about 3,000 eggs, which then hatch — as larvae — the following summer.
The larvae are harmless at first. But they feed on mice or other rodents, and if those animals carry the Lyme bacteria, the larvae become infected, too. After feeding on mice, the larvae huddle in the ground for the winter, then emerge the following spring as nymphs that can potentially infect humans.
But a number of things can affect how many ticks there are in any given area in any year. A mild winter and a wet spring, for instance, can boost the tick population — and may this year.
So can a bumper crop of acorns two years before the ticks appear, says Rick Ostfeld, an ecologist at the Institute of Ecosystem Studies, a private nonprofit research organization in Millbrook, N.Y.
“There are two pathways by which acorns have an effect,” he says. Deer love acorns, so when there’s a bumper crop of acorns, it lures deer deep into oak forests. Mice love acorns, too.
So lots of acorns means lots of mice survive the winter, which means that “two summers after a good acorn fall you have lots of infected nymphs,” he says. Since there were bumper acorn crops in 1997 and in 1998, Ostfeld predicts “a pretty bad summer for Lyme disease in 1999 and worse in 2000.”
Dr. Ned Hayes, an epidemiologist at the Centers for Disease Control and Prevention who specializes in bacterial diseases transmitted from animals to humans, is less convinced about this year’s forecast: “I wouldn’t make any predictions.”
But he and other Lyme specialists, among them, Dr. Bela Matyas, medical director of epidemiology at the Massachusetts Department of Public Health, say that if you’re at risk for Lyme disease, you should talk to your doctor soon about getting the vaccine.
The vaccine works by stimulating the immune system to make antibodies to a protein called OspA, which is found on the surface of the bacteria in the tick’s gut. The vaccine does not attack the tick itself. But when the tick sips a person’s blood, it sucks in the antibodies, which then kill the bacteria.
This process is not foolproof, however. If bacteria enter the body despite vaccination, they quickly stick a different protein called OspC on the surface. The vaccine doesn’t work against this protein, which means that if the first line of defense fails, you may still get infected.
Next month, the Advisory Committee on Immunization Practices, a group of experts that advises the CDC on vaccine issues, is expected to recommend that anyone at high risk of Lyme disease because of frequent or prolonged exposure to tick-infested habitats should consider being vaccinated.
For people with less frequent or less prolonged exposure, it’s unclear how much added benefit a vaccine provides over standard anti-tick precautions.
People with minimal exposure to tick-infested areas need not get the vaccine.
People who have uncomplicated arthritis from a prior Lyme disease infection and are at high risk should consider getting the vaccine, the committee is expected to say. But those who have Lyme disease that has not responded to treatment should not, because the vaccine could make things worse. In healthy people, however, initial data indicate that there are no serious side effects.
The bottom line is to discuss vaccination with your doctor and remember that it takes a while for the vaccine to kick in, it doesn’t work for everyone, and even when it does, it doesn’t protect against other tick-borne illnesses. This means you still have to take precautions to avoid ticks — forever.
- Look for the deer tick on your skin or clothing after walking in fields or woods. The tick – a dark speck the size of a poppy seed – is most likely to bite in the nymph stage.
- 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.
- Use insect repellants. Permethrin kills ticks on contact, but it can be irritating, so spray it on your clothes, not your skin. You can use DEET (diethyltoluamide) on your skin and clothes. State guidelines vary, but in Massachusetts and some other states, health officials say you should not use DEET on infants, and don’t use products with more than 15 percent DEET on children. Adults should use products with no more than 30 to 35 percent DEET. High concentrations of DEET may cause severe allergic reactions and seizures.
- When you get home from a tick-infested area, shower or bathe and remove any ticks with tweezers within 24-48 hours.
- If pets have been in tick-infested areas, check them, too, as well as areas where they sit or lie.
- If you become infected – you should notice a rash and flu-like symptoms – call your doctor; antibiotics are often effective if given early, but not always.
For more information, contact:
- The Lyme Disease Foundation, 1-800-886-LYME (or 1-800-886-5963) or on the Web, www.lyme.org.
- American Lyme Disease Foundation, 914-277-6970 or on the Web, www.aldf.com.
Lyme disease in Massachusetts
The original column in the Boston Globe contained a photo and a chart. The Photo Caption read:
- With summer — and tick season — fast approaching, there’s a new weapon available to reduce your chances of catching Lyme disease: a vaccine called LYMErix, approved by the Food and Drug Administration late last year. Now, the bad news. The vaccine isn’t approved for kids under 15 or people over 70. It protects about 80 percent of the people who get it, and that’s if you get three shots, which, according to current FDA licensing, must be taken over 12 months. If you get only two shots, a month apart, there’s only a 50 percent chance you’ll be protected. And no one knows how long the protection will last.
The chart data is available at the Boston Globe on Microfilm.