HERSHEY – Spring and summer are the peak times for Lyme disease in the United States. That’s when the Ixodes tick, which transmits Lyme disease, is most actively looking for a meal. The only time infected ticks can pass on Lyme disease is during feeding, and only this tick can transmit Lyme disease, not the American dog tick or the lone star tick.
Lyme disease is named for Lyme, Conn., where it was first identified as a disease. While Connecticut has the most cases per 100,000 population, New York and Pennsylvania had the greatest number of total cases in 2005. It is a fairly common illness in the northeastern United States with thousands of cases reported annually, but it is quite rare elsewhere.
Tick eggs hatch and form larvae that attach to small animals, such as mice. They feed, drop off and spend the winter in the soil, during which time they become nymphs. In spring they emerge and climb onto grasses and shrubs awaiting a passing mammal, such as another mouse, a deer, dog or human. They cannot jump but depend on the animal or person passing close enough for them to grab on with their front legs. They crawl around their host for hours looking for a spot to attach. Once attached, they stay in place for two to three days and then begin to feed, taking blood from the host and swelling to many times their previous size. Then they drop off, grow in the ground into adults and repeat the process of climbing onto a host, feeding and, if female, laying eggs.
Ticks can become dehydrated easily in the summer sun, so they tend to stay around higher grasses and brush. For that reason, it is unusual to pick up a tick in well-tended lawns. It’s more likely to get a tick in areas where grass is higher and around shrubs and woods. Dogs can carry ticks indoors on their coats. Only about a third of tick nymphs carry Lyme disease, and they do not pass the disease until the end of feeding. Because it takes hours to attach and a couple days to feed, there is plenty of time to find ticks if people look over their entire bodies after being outside near tick-infested areas.
Ticks are less likely to latch onto a person wearing an insect repellent with 20 to 30 percent DEET on the clothing. Insecticide containing permethrin, which is derived from chrysanthemums, applied to clothing is rapidly fatal to ticks and to other insects, such as bees. It is safe for humans and dogs but toxic to cats. Long sleeves and pants with legs tucked into socks can deter ticks from getting on the skin.
If a tick is crawling on the skin, pick it up with tweezers or a tissue or paper towel. If it is attached, do not attempt to burn it or smother it. Simply grasp it with tweezers near the skin and gently apply traction. It might take a minute, but with the gentle pulling, the tick will release its jaws and come away. There might be a thin bit of paper-like adhesive that comes away with the tick.
If the tick is not swollen, it did not feed and there is no risk of Lyme disease. No treatment is needed except for cleansing of the skin. If the tick is swollen, contact a doctor. If it is clearly a tick that can carry Lyme, it might be appropriate to take a one-time dose of antibiotic to prevent Lyme. Otherwise, antibiotic treatment is of no benefit.
Sometimes the tick is not noticed because, even when engorged, nymphs are very tiny. In three to 30 days after infection, about 70 to 80 percent of people get a red rash that tends to form a single or double ring that expands around the site of the bite. This is called erythema chronicum migrans or ECM. Flu-like symptoms — joint and muscle pains, fever, fatigue, chills and swollen lymph nodes — can develop. Meningitis-like symptoms of stiff neck and headache can also occur. The presence of an ECM rash is sufficient to begin treatment in someone who lives in an area where Lyme disease is likely. If no rash is present or if it is not clearly an ECM rash, a blood test can be done to help make the diagnosis.
Treatment of Lyme disease is with oral or intravenous antibiotics for two to four weeks depending on the degree of illness and the person’s other health status. There is currently no evidence that longer courses of therapy are necessary, and such treatment is not supported by the Infectious Diseases Society of America or the Centers for Disease Control and Prevention.
Untreated, Lyme disease can cause a destructive inflammation of the joints that looks like rheumatoid arthritis or can affect the heart. So-called chronic Lyme disease does not occur if treated with appropriate antibiotic therapy. Continued joint pains, swollen lymph nodes and fatigue are not due to persistent infection but are likely the result of an overactive immune system.
Advanced planning can reduce the risk of getting a tick. Light-colored, long-sleeved shirts and long pants tucked in, topical insecticide or repellents, and thorough inspection of one’s entire body once indoors are important parts of prevention of Lyme disease. For information on Lyme disease, visit here or here on the Web.