The guidelines for diagnosing and treating Lyme disease may soon be changing, although pediatricians aren't expected to readily adopt all the recommendations.
Closed in September, the comment period closed on a new set of guidelines for the prevention, diagnosis, and treatment of Lyme disease. The guidelines have several updates, but one of the primary changes is the recommendation to use doxycycline for treatment of Lyme disease infection and as prophylaxis after a high-risk tick bite—even in children. Pediatricians, however, are not used to using doxycycline in children due to concerns about damage and staining to teeth, and the authors of the guidelines anticipate pediatricians will hesitate to adopt the change, opting instead to continue prescribing other antibiotics.
Paul G. Auwaerter, MD, president of the Infectious Diseases Society of America, a Sherrilyn and Ken Fisher professor of medicine at the Johns Hopkins University School of Medicine, in Baltimore, Maryland, and co-author of the guidance, says the guidelines were drafted by a panel from the Infectious Diseases Society of America, the American Academy of Neurology, and the American College of Rheumatology, with input from a number of other organizations and experts. There is no word yet on when final recommendations will be published.
Lyme disease is found in 3 expanding regions of the United States, according to the proposed guidelines--the northeast states from Virginia to eastern Canada, the upper Midwest, and northern California. Presence of a rash is still a hallmark sign of infection following a tick bite, according to the report. The rash associated with Lyme disease—erythema migrans—is present in roughly 80% of cases and its presence is enough to warrant initiation of treatment for Lyme disease, according to the guidance. Blood testing is generally not recommended, as only about 33% of patients will have detectable antibodies along with the erythema migrans rash. The recommendations also do not suggest performing any testing on the ticks. Identifying the tick and examining whether it is engorged, indicating more prolonged attachment and feeding time, is more helpful, according to the guideline. This is because Borrelia burgdorferi, the primary bacteria that causes Lyme disease is found in a tick's midgut and is only activated some time after the tick attaches to a host and begins to feed. The bacteria must first migrate from the midgut to the mouth of the tick, and is then passed to human hosts by reflux through the tick's salivary glands during feeding. Generally, ticks must feed for more than 36 to 48 hours to pass the bacteria to its host, although infection may occur sooner.
The infection process for Lyme disease is clinically complex, with a wide range for the latent period after exposure and before an infection presents. Symptoms of Lyme infection may include localized skin lesions at the site of the bite, neuropathy, meningitis, cardiac conduction problems, and arthritis. Manifestations can occur as early as a few days after a tick bite, to as late as several months after.
Serum antibody testing is highly sensitive and the first line method of testing for Lyme disease, according to the guidance, although false negative results may occur early in the infection process as a detectable antibody response may take some time to develop. Therefore, testing isn't always recommended, particularly for patients who are asymptomatic.
Lyme disease is treated with antimicrobials including doxycycline, penicillin, amoxicillin, cefuroxime, ceftriaxone, and azithromycin. Oral antibiotics are usually sufficient and preferred, according to the guidance, but there are some indications in which intravenous antibiotics may be used.
One of the major changes in the proposed guidelines is the recommendation to use doxycycline in children younger than 8 years. Previously, doxycycline was not recommended for use in children over concerns about tooth enamel damage and discoloration. The new guidelines, however, dismiss this concern and note instead that doxycycline is effective against more than one tick-borne disease and can be given for children with broader manifestations. It is also the only oral option that is effective against Lyme meningitis outside of parenteral options, which carry additional risks. However, the guideline authors note that amoxicillin may still be more frequently used in pediatric patients simply because it is more commonly used in pediatric practice. The dosing for doxycycline is 4.4 mg/kg—maximum dose 200 mg—for children. The proposed recommendations also include post-exposure prophylaxis of a single dose of doxycycline for pediatric patients when an engorged tick has been removed. It is only recommended to use prophylactic antibiotic therapy within 72 hours of removing an identified, high-risk tick exposure, according to the guidelines. This includes bites from identified Ixodes ticks; bites that occur in highly endemic areas for B. burgdorferi-infected ticks; and when ticks are engorged and attached for more than 36 hours.
The safest bet is to prevent tick exposure and Lyme disease infection from the start. The proposal lists physical barriers such as protective clothing that is light in color to see ticks, special cleaning techniques when ticks are found on clothes, and treating pets. Repellants with N,N-Diethyl-meta-toluamide (DEET), picaridin, 380 ethyl-3-(N-n-butyl-N-acetyl) aminopropionate (IR3535), oil of lemon eucalyptus, or permethrin 381 are strongly recommended, with the authors noting that there is no evidence to support the efficacy of botanical agents or essential oils in repelling ticks. Concerns have been raised about the safety of products containing DEET, however the proposed guidelines state that there are actually very low rates of adverse effects with products containing DEET as long as they are used as labeled.
The guidelines also make suggestions on tick removal, recommending against burning attached ticks or using chemicals or petroleum products for removal. Instead, the guidance suggests removing ticks mechanically with a clean tweezer inserted between the tick's body and the host's skin.
There is still more research to be done, and official recommendations and clinical guidance won't be issued until after comments are reviewed and considered. While the guidelines cover a lot of specifics, there is also a lot of room for additional research, Auwaerter says.
"We still have questions and are advocating for more research into tick-borne diseases. In the meantime, we are updating the Lyme disease guidelines to promote safe, effective, proven treatment," Auwaerter says. "The guidelines use the best available evidence to guide decisions regarding diagnosis and treatment of B. burgdorferi infections."