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Monday, June 16, 2014

Lyme Disease QA: Prevention and Testing

 Each year, about 30,000 cases of Lyme disease are reported to the CDC, although health officials believe the actual case number is higher. To learn more about prevention and testing for the disease, WebMD Senior News Health Editor Ashley Hayes talked to CDC Lyme disease expert Paul Mead, MD, MPH, and to Beth Daley of the The New England Center for Investigative Reporting. The center today  published a report that looks at issues around Lyme disease testing.  Please return  here at noon on Wednesday, June 18 for a live chat with Mead, Daley and Dr. Arefa Cassoobhoy of WebMD about Lyme disease.

Warmer weather, from spring to early fall, means ticks are at their most active. That increases your chances of a tick bite and your risk of Lyme disease.

Lyme disease is spread through the bite of a blacklegged tick.  Most U.S. infections happen in the Northeast and mid-Atlantic states, from northeastern Virginia to Maine; North-Central states, mostly Wisconsin and Minnesota; and on the West Coast, particularly Northern California.

Here’s what you need to know:

What are the symptoms?

The “classic symptom” of early Lyme disease is a red, expanding rash, says Paul Mead, MD,  medical officer with the CDC. The rash, which can have a bulls-eye appearance, isn’t always present; it’s seen in 60% to 80% of cases, he says.

The rash develops at the site of a tick bite, although a person may not be aware they’ve been bitten. Lyme disease is usually transmitted by nymph ticks, and those are very small, Mead says.

Also, flu-like symptoms — muscle aches and pains, a fever of about 101 degrees or so, headaches, and “that kind of yucky feeling” — are common, with or without a rash, Mead says. If you live in an area where Lyme disease is common and have these symptoms, you and your doctor should consider it a possible culprit.

In later stages of the disease (usually starting a couple of weeks after a bite) people can have Bell’s palsy, a type of partial facial paralysis. The disease can also spread to the joints, causing arthritis. In rare cases, complications such as inflammation of the heart, leading to an irregular heartbeat, are seen, Mead says.

What do I do if I find a tick on my body?

Ticks can attach to any part of the body, but may often be found in hard-to-see areas such as the groin, armpits, or scalp, the CDC says. It’s important to remove a tick as soon as possible, as it has to remain attached for at least 24 hours to transmit Lyme disease.

Remove an embedded tick with fine-tipped tweezers, Mead says. “Grab it as close as you can to the skin, and simply sort of pull directly away from the skin” using a slow and steady motion.

In some cases, a bit of the tick’s head or mouth parts may remain, he says. Clean the site of the bite and “typically, those will fall out.”

If you develop a rash or fever within several weeks, see your doctor — and be sure to mention the bite.

 A tick bit me. Do I have Lyme disease?

It depends on the type of tick, where you acquired it, and how long it was attached, the CDC says. Always remove ticks promptly and, if you live in a high-risk area, check your body daily.

“It’s not true that every single tick bite is going to pose a risk, but you don’t really know, so you have to remove the tick,” Mead says.

Remember, too, that ticks can carry other diseases besides Lyme disease.

How can I prevent tick bites?

Ticks tend to live in wooded and bushy areas with high grass and leaf litter, so take steps to clear your yard. Blacklegged ticks “like cool, dark, moist areas like leaf litter — they don’t like sunny, dry, open areas,” Mead says. Gravel or wood-chip barriers between patios and kids’ play areas and forested areas can also help.

Use repellents on skin (use a product with 20% to 30% DEET) and on clothing and gear (use products containing 0.5% permethrin).

Bathe or shower within 2 hours of coming indoors, if possible, to easily find and wash off ticks — research has shown it may lessen your risk of infection, Mead says. Do full-body checks using a hand-held or full-length mirror. Parents should check children for ticks under the arms, in and around the ears, inside the belly button, behind the knees, between the legs, around the waist, and especially in the hair.

Don’t forget to check your gear (such as coats or backpacks) and pets. “Pets can be vehicles for ticks to come into the house,” Mead says. Using pet tick control can help.

How do I get tested for Lyme disease?

You must visit your doctor to be tested.

The CDC recommends that only FDA-approved tests be used to diagnose Lyme disease.  Reporter Beth Daley recommends asking your doctor what test he or she uses to diagnose Lyme disease and whether it’s FDA-approved. If you have a bulls-eye rash, your doctor may diagnose you without testing, she says.

Some alternative tests have been developed, but can lead to misdiagnoses, Mead says.

“I think patients get information from those and have difficulty understanding the limitations of those tests,” he says. “Patients are eager to get answers, but a misleading answer is not really helpful.”

The CDC says on its web site that before it recommends new tests, “their performance must be demonstrated to be equal to or better than the results of the existing procedure, and they must be FDA-approved.”

What tests for Lyme disease are valid?

An FDA-approved test uses a two-step method. The first test looks for increased disease-fighting antibodies in the blood that react to Lyme disease bacteria, according to Daley. If that test is positive (meaning you have the increased antibodies), a second test called a “Western Blot” is used to more accurately identify antibodies specific to the Lyme disease bacteria. Results are considered positive only if both tests are positive, according to the CDC. The tests need to be done together.

A person can test negative and still have Lyme disease. That’s because antibodies take a few weeks to develop, and the test can be done too early, the CDC says. The test will likely pick up Lyme disease after 4-6 weeks; if you test negative but still are having symptoms, you can be retested.

Posted by: WebMD Blogs at 1:20 pm

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