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| Lyme
Disease
Lyme disease is an infectious disease that can cause numerous different symptoms and can be extremely difficult to diagnose. It is named after Old Lyme, Connecticut where it was discovered in 1975. It is a bacterial infection caused by the bite of a very small infected tick that is called the deer tick or the black legged tick. In some parts of the country Lyme disease is very common. The highest incidence is in the northeastern United States, but it also occurs as far west as California and as far south as Florida. The real incidence in the Panhandle area of Florida is not known, but it is probably not very common. I called several different experts around the country in an attempt to see if it is very common in the Panhandle area of Florida. Etiology It is estimated that about 2-3% of the deer ticks in the southeastern United Stated are infected with the bacteria that causes Lyme disease. This bacteria is called Borrelia burgdorferi. The infected ticks are distributed around the country in pockets rather than distributed uniformly. In some parts of Connecticut, up to 70% of the ticks are infected with the bacteria and therefore capable of transmitting Lyme disease. The deer tick is about the size of a pinhead and they tend to brush off very easily as opposed to the much larger wood tick that is much more common in Florida. In order for the tick to live and spread Lyme disease, it must feed on an animal. In the northern states, the most common reservoir is the white-footed mouse. This mouse does not live in the southeastern United States so the ticks must feed on other sources. Fortunately, the ticks tend to feed on lizards which cannot support the life cycle of the bacteria that causes Lyme disease very well, so the spread of Lyme disease is much less common in the south. The ticks thrive on lizards, but the bacteria will not live in the blood of the lizard very well at all. Therefore, immature ticks are not infected with the bacteria when they feed on the lizard. This makes it difficult for the bacteria to be spread from tick to tick. It is not known to what extent the bacteria is spread by other animals. The bacteria has been found in ticks that feed on birds. Birds could carry the disease to far-off areas. Lyme disease is not transmitted from person to person. It can be transmitted to dogs, cats and horses and causes symptoms similar to that of humans. They may have fever, lameness and swollen joints. Diagnosis The screening blood test that is used for Lyme disease has a very high false positive rate. This makes it extremely important to do a confirmatory test called the Western blot method. In the past, the Western blot has not been done so there are numerous people that are incorrectly diagnosed as having Lyme disease. About 10 to 15% of all screening tests for Lyme disease come back positive. It is very important to request the Western blot if you have a positive screening test. Some commercial labs will not perform the Western blot unless it is specifically asked for. It is also important to realize that the blood test for Lyme disease may take several weeks or months to become positive after infection. Therefore you may have the typical rash and symptoms of Lyme disease, but the blood test will still be negative. In this case most physicians will go ahead and treat with antibiotics. Symptoms Stage 1 consists of a Flu-like illness staring several days after the
tick bite. Symptoms such as malaise, fatigue, chills, fever, headache,
stiff neck and backache are typical. A characteristic rash (erythema
migrans) can be recalled by 20% of patients. It is a small red papule
around the site of the tick bite that starts 3 to 30 days after the
bite. It gradually spreads in a circular fashion around the tick bite
that usually attains a size of 2 inches or more. The central area will
fade creating a "bulls-eye" type appearance. This stage of
Lyme disease it is practically 100% curable with antibiotics. Patients that are not treated may go on to develop joint, heart or nervous system manifestations. Joint manifestations are usually in the form of swelling and pain in the large joints such as the knees, shoulders and elbows. Several joints are involved at one time and the involvement is not symmetrical. Heart involvement is usually manifested as a heart block that promptly resolves after antibiotic treatment. Nervous system involvement can be in the form of meningitis, facial nerve paralysis, inflammation of the brain or painful disorders and weakness in the limbs caused by nerve inflammation. Patients with untreated Lyme disease may develop serious joint involvement of one or more joints that may not resolve with antibiotics late in the course of chronic Lyme disease.
The usual antibiotics for treating stage 1 are penicillin, a cephalosporin, doxycycline or erythromycin. Stage 2 and 3 are treated for a longer period of time and sometimes need to be treated with IV antibiotics. Stage 2 and 3 require careful monitoring over a period of several years depending on the severity of the infection. Prevention 1. Wear long pants and tuck the pants legs in socks. References * * * Readers may send questions to our email address. This column is for informational purposes only and is not a substitute for professional or medical advice. * * * |
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