Lyme disease is an illness caused by Borrelia burgdorferi, a member of the spirochete or spiral-shaped bacteria family. It was first officially recognized in the United States in 1975, after an unusual cluster of arthritis cases broke out in children from Lyme, Connecticut. What we now know as Lyme disease was reported in a grouse hunter from Taylor County, Wisconsin in 1969. It wasn?t until 1979 that additional cases of Lyme disease were reported in Wisconsin. The bacterium Borrelia burgdorferi was not even identified until 1982. There are about 12,000-16,000 cases of Lyme disease reported each year in the United States. Lyme disease has been reported in almost every state in the country, although most cases are concentrated in the coastal northeast, from Massachusetts to Maryland, the north-central states, especially Wisconsin and Minnesota, and the west coast, particularly northern California. Since 1980, there have been 6,089 cases of Lyme disease reported in Wisconsin, most of them coming from the northwestern or west central part of the state. I chose this topic because I knew that Lyme disease was an illness common to Wisconsin and I wanted to learn how to protect my friends and family from the disease.
Lyme disease is spread by the bite of ticks of the genus Ixodes that are infected with Borrelia burgdorferi. The deer tick is responsible for transmitting Lyme disease bacteria to humans in the northeastern and north-central United States. On the west coast, the bacteria are transmitted to humans by the blacklegged tick. Ixodes ticks are much smaller than common dog and cattle ticks. In their larval and nymphal stages, they are no bigger than a pinhead. Adults are only slightly larger. Ticks can attach to any part of the human body but often attach to the more hidden and hairy areas such as the groin, armpits, and scalp. For the most part, ticks transmit Lyme disease to humans during the nymph stage because they are more likely to feed on a person and they are rarely noticed because of their small size. Therefore, these nymphs have plenty of time to feed on blood and transmit the infection. This usually takes 2 or more days to occur. Tick larvae are smaller than the nymphs, but they rarely carry the infection at this stage and do not contribute in the spread of Lyme disease to humans. Adult ticks can transmit the disease, but since they are larger and more likely to be seen and removed they are less likely than the nymphs to transmit the infection. Ticks search for host animals from the tips of grasses and shrubs and transfer to animals or people that brush against the vegetation. Ticks do not fly or jump, they can only crawl. They feed on blood by inserting only their mouthparts into the skin of a host. The tick slowly enlarges as it feeds for several days. Although in theory Lyme disease could spread through blood transfusions or other contact with infected blood or urine, no cases have been documented. There is no evidence that a person can get infected from sexual contact, the air, food, or water, or directly from wild or domestic animals. Another untrue myth about Lyme disease is that insects such as mosquitoes, flies, and fleas can transmit the infection. Campers, hikers, outdoor workers, and others who frequently go through wooded, brushy, and grassy places are commonly exposed to ticks, which increase their chances of becoming infected with the Lyme disease bacteria.
Knowing the complex life cycle of the ticks that transmit Lyme disease is important in understanding the risk of obtaining the disease and finding ways to prevent it. The life cycle of these ticks takes 2 years to complete. It begins by adult ticks feeding and mating on a host in the fall and early spring. The female tick then drops off the host to lay eggs on the ground, which will hatch into larvae by summer. The larvae feed on mice and other mammals in the summer and early fall and then are inactive until the next spring when they molt into nymphs. The nymphs feed on small rodents and mammals in the late spring and summer and molt into adults in the fall, completing the 2-year life cycle. Larvae and nymphs become infected with Lyme disease bacteria when they feed on infected small animals, especially the white-footed mouse. The bacteria remain in the tick as it changes from larva to nymph or nymph to adult. These infected ticks then bite and transmit the bacteria to other rodents, animals, and humans all in their normal feeding behavior.
There are several symptoms and signs of early Lyme disease. These include fatigue, chills, fever, headache, muscle and joint pain, swollen lymph nodes, and the most common of all, a skin rash resembling a bull?s eye, called erythema migrans. Erythema migrans is a red circular patch that appears at the site of the bite 3-30 days after the bite of an infected tick. The rash then expands, sometimes spreading to other parts of the body. Common sites are the thigh, groin, torso and back, and the armpits. Some symptoms and signs of Lyme disease may not appear until weeks, months, or years after a tick bite. In late Lyme disease, arthritis may appear as brief spells of pain and swelling, most commonly in the knees and other large joints. About 10-20% of untreated patients will go on to develop chronic arthritis. Some people may develop complications involving the heart and nervous system. Some specific complications include heart blockages and heart rhythm irregularities. Nervous system abnormalities can include pain, numbness, Bell?s palsy, meningitis, encephalitis, and other peripheral nerve conditions. In some people the rash never forms and they only experience arthritis and others sometimes only have nervous system problems. In rare cases, Lyme disease contracted during pregnancy may lead to infection of the fetus and possibly causing a stillbirth to occur.
Lyme disease is often difficult to diagnose because its symptoms and signs copy those of many other diseases. The fever, muscle aches, and fatigue of Lyme disease can be easily mistaken for viral infections, such as the flu or mononucleosis. Joint pain can be mistaken simply for rheumatoid arthritis, while neurological signs can mimic those of multiple sclerosis. At the same time, other types of arthritis or neurological diseases can be misdiagnosed as Lyme disease. The only distinctive mark unique to Lyme disease is the erythema migrans rash, but is absent in at least ? of the people who become infected. The antibody blood test used most often in detecting Lyme disease bacteria is called an ELISA test. When an ELISA test is positive, it should be confirmed with a second, more specific test, called a Western blot. These tests are most useful in later stages of illness, but even then they may give inaccurate results. Laboratory tests for Lyme disease have not yet been standardized nationally because they are still working on better, more accurate tests. When diagnosing Lyme disease one should take into account the possible exposure to ticks, the symptoms and signs, and the results of blood tests taken for the determination of whether the patient has antibodies to Lyme disease bacteria or not.
Nearly all Lyme disease patients can be effectively treated with antibiotic therapy. If Lyme disease is diagnosed during the early stage, it is usually easily treated with antibiotics such as tetracycline, penicillin, and erythromycin. Antibiotics, like doxycycline, cefuroxime axetil, or amoxicillin taken orally for a few weeks can speed the healing of the erythema migrans rash and usually prevent other symptoms such as arthritis or neurological problems. Lyme disease patients with neurological symptoms are usually treated with the antibiotic ceftriaxone given intravenously once a day for a few weeks. Most patients recover fully. Lyme arthritis can be treated with oral antibiotics, but patients with severe arthritis may be treated with ceftriaxone or penicillin given intravenously. These patients may also be given anti-inflammatory drugs to ease their discomfort and aid to their healing as well. To treat Lyme disease heart symptoms, doctors use the antibiotics ceftriaxone or penicillin given intravenously for 2 weeks. If these symptoms persist, patients may also be treated with corticosteroids or given a temporary pacemaker. People with Lyme disease rarely experience long-term heart damage.
There are a few things you can do to prevent Lyme disease. After being outdoors, check yourself for ticks, so you can remove them before they embed and have the chance to transmit the bacteria. Wear light-colored clothing so it is easier to spot ticks. Tuck your pants into your boots; wear long-sleeved shirts and a hat to protect yourself. You should also use a tick/insect repellent with DEET to further ward off ticks. Recently, in 1999, a vaccine was produced to help prevent Lyme disease. The vaccine can be given to people 15-70 years old. It is given as an injection, involving 3 doses. The 1st dose can be given at any time, preferably early in the year. The 2nd dose should be given 1 month after the 1st one. Finally, the 3rd dose of the vaccine should be given 12 months after the first one. Since it is not known how long the vaccine protects you, no plan or schedule for giving any booster doses has been set. Until we can find a complete cure, researchers are developing effective strategies for ridding areas of deer ticks completely.
Lyme disease has only been around for about 25 years, yet science has made great advances in developing preventative tools, the most recent being the creation of the Lyme disease vaccine. I learned a lot about Lyme disease from the transmission of it to the treatment and preventative measures you can take against it. Lyme disease is often taken very lightly, but I have learned that it can cause a rash, arthritis, and even neurological problems, which should not be taken lightly at all. The key to not contracting the disease is to be careful and inspect yourself after being outdoors, especially when near wooded areas.
U.S. Department of Health and Human Services. Lyme Disease Vaccine. Washington, D.C.: National Immunization Program, November 1999.
U.S. Department of Health and Human Services. Lyme Disease. Washington, D.C.: National Institutes of Health, April 1998.
Wisconsin Department of Health. Lyme Disease. Madison, WI: Bureau of Communicable Diseases, March 1999.