Mosquito and Tick-Borne Diseases: Lyme Disease

Lyme Disease

In 1977, a group of children in and around Lyme, Connecticut, developed similar cases of arthritis. Research showed that this was an infectious disease caused by a bacterium that is transmitted to people via tick bites.

Ticks ingest the bacteria that cause the disease from deer or rodent carriers. Not all species of ticks carry Lyme disease, but any tick bite should be considered suspicious.

Ticks feed by inserting their mouths into skin and slowly sucking blood. It usually takes 36 hours of tick attachment before transmission occurs, so it is very important to check for ticks after being outside, especially in the spring.

Lyme is mostly, but not exclusively, found in the Northeast United States. There are around 16,000 cases of the disease in the United States each year. Lyme is the most common tick-borne infection in the United States and effects people in almost every state.

People who live or work in places near woods or overgrown brush are at risk.

Hiking, camping, fishing, and hunting can also be risk factors for the disease.

Reported Lyme disease cases by state (1999).

Symptoms of Lyme

After a tick bite where transmission occurs, the person often develops a small red bull's-eye-shaped rash. Other symptoms that follow are fever, fatigue, headache, and muscle and joint aches. The incubation time is seven to fourteen days, but symptoms can show up as quickly as three days after transmission or as long as 30 days later. Some people don't really get many symptoms at all and others experience very generalized symptoms.

If the bacteria get into the nervous system, they can cause meningitis and palsy. If they get into the musculoskeletal system, they can cause severe muscle and joint pain. In the rare instances when they get into the heart, they can cause a variety of blockages. Undiagnosed Lyme can cause joint swelling, sleep disturbance, fatigue, and even personality changes.

Licking Lyme

Diagnosis is based primarily on the appearance of symptoms, particularly if the person knows they've been bitten by a tick. Blood tests help to confirm exposure. Because antibodies to Lyme stay in the system for months and even years, the blood tests aren't always accurate and false positives can occur.

Lyme disease is difficult to diagnose. Doctors diagnose Lyme disease based on symptoms, history, and blood test results. If there is a tick bite and a rash, that is strong evidence of infection. However, not all victims get a rash, and not everyone remembers being bitten. Blood tests, also known as Lyme titers, cannot diagnose the disease alone, but they are used to confirm a diagnosis.

The most common tests look for antibodies to the bacteria that causes Lyme disease. However, it takes two to six weeks after infection for those antibodies to be made, so a blood test right after a tick bite may show a false negative. Other bacterial infections may also cause a blood test to be positive when the patient doesn't have Lyme.

To confuse the issue even more, antibodies to the bacteria that causes Lyme disease persist in the body for months and even years after an infection—even if the infection was treated successfully—so the presence of antibodies doesn't always make it clear that an active infection is present.

PCR tests to detect the bacteria itself might work, but they haven't yet been standardized for Lyme disease.

Lyme disease is effectively treated with antibiotics when it is caught early. The treatment usually lasts for three to four weeks. Later stage disease may require intravenous antibiotics for four weeks or more, depending on how bad it is.

Prevention Plays a Key Role

Preventive measures can help reduce the risk of exposure. It is important to avoid infested areas, especially in the spring. Ticks thrive in moist, shaded environments where deer and rodent hosts are abundant.

Wearing light-colored clothing makes it easier to find ticks before they bite. Long-sleeved shirts, tucking pants into boots or socks, and wearing boots that come up above the ankles can also help. Bug sprays that contain DEET or permethrin are also effective ways to prevent tick bites.

A New Vaccine

A vaccine for Lyme disease, called Lymerix, received FDA approval and it was used in the United States for a few years. However, as of February, 2002, the vaccine was taken off the market in the United States. The manufacturer says that demand was very low, but there has also been some controversy about whether the side effects, like arthritis and muscle pain, were too similar to the symptoms of the disease. In other words, some who got the vaccine thought it gave them the disease. Although there was low demand for the vaccine, the number of Lyme cases has not dropped, indicating that there is still a need for a safe and effective Lyme vaccine.

Excerpted from The Complete Idiot's Guide to Dangerous Diseases and Epidemics © 2002 by David Perlin, Ph.D., and Ann Cohen. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.