November 2006

A 10-year-old child from western Pennsylvania came into the office for an erythema migrans that developed in the previous few days. He had been playing in the yard but his mother doesn’t recall a tick bite. She is concerned, however, because the rash has expanded in size over a period of days. The child complains of headache, a stiff neck and says he is tired.

Answer

The child has Lyme disease. The Infectious Diseases Society of America recently updated its Lyme disease guidelines regarding the epidemiology, clinical features, diagnosis and treatment of Lyme disease, according to Gary P. Wormser, MD, lead author of the guidelines, chief of the division of infectious diseases and vice chairman of the department of medicine at New York Medical College in Valhalla, N.Y.

According to Wormser, the new guidelines include the following:

• More information regarding the diagnosis and background of Lyme disease.
• Addition of a discussion of borrelial lymphocytoma and acrodermatitis chronica atrophicans.
• Addition of human granulocytic anaplasmosis and babesiosis, both of which are also deer tick-transmitted infections.
• The recommendation of a single dose of up to 200 mg of doxycycline as prophylaxis for certain children older than 8 who have been bitten by an engorged, nymphal-stage deer tick.
• A proposed definition for post-Lyme disease syndrome.

“The updated guidelines were an evidence-based approach and there are extensive references for the scientific evidence that formed the basis for these guidelines,” said Eugene D. Shapiro, MD, FAAP, one of the authors of the guidelines and professor at Yale University School of Medicine Department of Pediatrics.

Disease transmission

The microorganisms that cause Lyme disease, human granulocytic anaplasmosis and babesiosis are found in mice and some other small mammals. Deer ticks acquire the infection from these mammals and subsequently may transmit the microorganisms to people. Human granulocytic anaplasmosis is a tick-associated disease caused by a species of bacteria called Anaplasma phagocytophilum. The most common features of this condition are high fever and thrombocytopenia, often accompanied by myalgia and headache, according to the guidelines. Babesiosis is an infection that affects the red blood cells, and is transmitted through the bite of a deer tick. In the United States, most patients who are not immunucompromised are either asymptomatic of have only mild symptoms, the authors wrote.

Treatment

The vast majority of patients with Lyme disease are cured by a simple course of antibiotics. Occasionally, people who are treated adequately with antibiotics may have persistence of some nonspecific symptoms after the antibiotic course has been completed. The updated guidelines discuss post-Lyme disease syndrome, which generally resolves within weeks without additional antimicrobial treatment. Wormser and colleagues also discuss so-called “chronic Lyme disease,” for which the panel found no scientific evidence to support its existence.

Within both the updated and old guidelines, the researchers stated that Lyme disease is a curable disease. “Patients should be reassured that Lyme disease is a curable infection like other spirochetal infections, and long-term antibiotic therapy is neither helpful nor safe,” Wormser told Infectious Diseases in Children. “There is also no convincing scientific evidence to justify prolonged antibiotic therapy or to support the existence of antibiotic-refractory, symptomatic Borrelia burgdorferi infection, which is also known as chronic Lyme disease,” Wormser said.

According to the IDSA guidelines, some tick bites that occur in people older than 8 may be treated with one dose of doxycycline if: the Ixodes scapularis tick has been attached for at least 36 hours, if treatment can begin within 72 hours after the tick was removed, and if the ecologic information indicates the local rate of infection with B. burgdorferi bacteria is over 20%.

The major difference between both sets of guidelines is the addition of human granulocytic anaplasmosis and babesiosis as well as updated information about prophylaxis for tick bites and recommended duration of treatment. Since all three of these infections are transmitted in a similar way, it is important for people to be aware that there are other diseases in addition to Lyme disease that can be transmitted from deer ticks, the researchers wrote.

For more information:

• Wormser GP, Dattwyler RJ, Shapiro ED, et al. The clinical assessment, treatment and prevention of Lyme disease, human granulocytic anaplasmosis and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. 2006;43:000.
• Wormser GP, Nadelman RB, Dattwyler RJ, et al. Practice guidelines for the treatment of Lyme disease by the Infectious Diseases Society of America. Clin Infect Dis. 2000;31 Suppl 1:1-14.