If you live in a town where others have gotten Lyme disease, you're probably already a little paranoid about ticks. There are actually hundreds of types of ticks, but Lyme is only transmitted by two species of black-legged ticks that are known as deer ticks because deer often carry them from place to place. However, these ticks also hitch a ride on mice and other small animals, and that's where they pick up the bacterium, called Borrelia burgdorferi, which causes Lyme disease. Fortunately, Lyme disease doesn't spread from person to person, but a child can catch it more than once.
Young deer ticks, known as nymphs, cause most of the infections, partly because they're so small and hard to spot. A nymph is about the size of a poppy seed, and an adult is the size of a sesame seed. Hungry ticks often wait on blades of grass and try to grab on to an animal or a person who brushes up against them. A bite is painless, but a tick can cling to your child's skin -- feeding on the nutrients in her bloodstream -- for several days. However, even if your child gets bitten, she won't necessarily get Lyme disease, since only 10 to 30 percent of these black-legged ticks actually carry the bacteria, says John Brownstein, PhD, an epidemiologist at Harvard Medical School. And a tick usually needs to be attached for at least 36 to 48 hours before it can transmit the bacteria. If you remove it before then -- by grasping it with tweezers and pulling it straight out -- it is very unlikely that your child will become infected.
The hallmark symptom of Lyme disease is a rash called erythema migrans (EM) that appears at the site of the tick bite within about a month. It can be as small as a dime or as wide as your child's entire back, and it's often found on the thighs, groin, trunk, or armpits. While the rash is often described as looking like a bull's-eye -- with a red ring that expands outward from a clear area in the center -- it's actually more common for the rash to be uniformly red, says Eugene Shapiro, MD, professor of pediatrics at Yale University School of Medicine. About 20 percent of people develop a rash in more than one spot, which is a sign that the bacteria have already spread into the bloodstream.
Unfortunately, anywhere from 10 to 65 percent of people with Lyme disease don't recall getting the telltale EM rash, says Brian Fallon, MD, director of the new Lyme Disease Research Center at Columbia University. It's hard to nail down an exact number because some people who get a rash never notice it -- since it's not itchy or painful and might be on a hidden spot like the scalp -- or the rash may get misdiagnosed as something else. Some kids with Lyme disease get flulike symptoms. When Jake Behr, of Bethlehem Township, New Jersey, became sick with a headache and fever, his doctor initially diagnosed the 8-year-old with an ear infection. It wasn't until his parents saw a rash on his shoulder and called the doctor back that the doctor realized Jake had Lyme disease.
If the infection isn't diagnosed and treated with antibiotics, more than half of patients will eventually develop Lyme arthritis -- painful and swollen knee joints -- which can become chronic in up to 20 percent of cases, according to the National Institutes of Health. "This bacterium tends to attach itself to tissues, including nerves and brain tissue, rather than staying in the bloodstream," explains Dr. Fallon. A child with Lyme disease can have neurologic symptoms such as temporary paralysis of facial nerve muscles (Bell's palsy), a stiff neck, numbness, mood swings, and extreme fatigue. "Some kids may even appear to have ADHD because they can't pay attention in class -- and they'll only get diagnosed with Lyme disease and treated with antibiotics once they develop a more typical symptom like joint pain or nerve palsy," says Dr. Fallon.
Lyme disease is also a difficult diagnosis because blood tests alone aren't very reliable; they frequently have false-positive or false-negative results. The tests can only detect antibodies that your child has made (recently or in the past) in reaction to the bacteria, not the actual bacteria. Since the body doesn't produce measurable levels of antibodies until two to four weeks after a tick bite, tests will be negative if they're done too soon. On the other hand, if your child has an "off-the-charts" test result, that doesn't necessarily mean he has a very bad case of Lyme, says Dr. Fallon. "High antibody levels could just show that he has a strong immune system that's fighting off a present infection or has fought one in the past."