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Current Trends Update: Lyme Disease and Cases Occurring during Pregnancy -- United States

Lyme disease is a tickborne illness caused by a spirochete, Borrelia burgdorferi. The number of cases reported to CDC has increased over the past 2 years so that Lyme disease is now the most commonly reported tickborne illness in the United States. Although it is reportable in only a few states, informal national surveillance was initiated by CDC in 1980 and has been compiled annually since 1982. In 1980, 1982, and 1983, 226, 491, and 599 cases, respectively, were reported in the United States. In 1984, a provisional total of 1,498 cases was reported (Table 2). For Lyme disease patients for whom 1983 and 1984 surveillance data are available, ages ranged from 1 year to 81 years (median 34 years). Fifty-four percent of cases occurred among males. Eighty percent of cases occurred during the 4-month period May-August, with the peak incidence in July.

Since 1980, reported cases of Lyme disease have occurred in an increasing number of states. Lyme disease was acquired in 11 states in 1980 and 1982, 18 states in 1983, and 21 states in 1984. Increasing numbers of cases have occurred in three states outside previously recognized endemic areas: Arkansas, North Carolina, and Texas. Isolated, serologically confirmed cases have been acquired in Florida, Georgia, Indiana, Michigan, New Hampshire, Virginia, and Tennessee. However, in all reporting years, over 90% of all cases were acquired in only seven states: Connecticut, Massachusetts, Minnesota, New Jersey, New York, Rhode Island, and Wisconsin. In addition to the states listed in Table 1, isolated, clinically suspected but unconfirmed cases of Lyme disease have been reported from Kentucky, Maine, Missouri, Montana, Ohio, and Vermont.

The possible association between Lyme disease during pregnancy and adverse outcome has recently received attention. Transplacental transmission of B. burgdorferi has been documented in a pregnant woman with Lyme disease who did not receive antimicrobial therapy. She delivered an infant with a congenital heart defect (1). The relationship between the intrauterine infection and congenital heart defect has not been established. In an effort to assess the risk of Lyme disease during pregnancy, the state and territorial epidemiologists and CDC have established a registry to enroll cases of Lyme disease in pregnant women before the outcome of pregnancy is known. Of the 19 pregnancies evaluated to date, none resulted in a child with a congenital heart defect. However, other adverse outcomes were found, including intrauterine fetal demise in the second trimester, prematurity, and developmental delay with cortical blindness. None of the adverse outcomes have been documented to be caused by Lyme disease. Outcomes of 14 of the pregnancies were completely normal. The risk of adverse outcome for pregnancies complicated by Lyme disease is not currently known. Reported by State and Territorial Epidemiologists; Respiratory and Special Pathogens Epidemiology Br, Div of Bacterial Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: Lyme disease, first described in 1977 (2), is characterized by a distinctive skin lesion, erythema chronicum migrans (ECM), which starts as a red macule at the site of a tick bite and expands to become an annular erythema with central clearing. Some patients develop systemic manifestations, including neurologic, cardiac, and arthritic abnormalities weeks to months after the skin lesion. B. burgdorferi has been isolated from cerebrospinal fluid (3) and visualized in synovia of patients with Lyme disease (4), suggesting the spirochetes can persist in various sites in the body and may be responsible for the systemic manifestations.

Because antimicrobial therapy decreases the morbidity from Lyme disease, it is important that cases be recognized and patients treated. In endemic areas, Lyme disease can be diagnosed if the typical ECM skin lesion is present. Serologic tests have been developed to measure antibody against B. burgdorferi (5,6). These tests, when positive, can help support the clinical suspicion of Lyme disease in atypical cases, such as those without ECM or those occurring outside recognized endemic areas. However, serologic tests are often negative, particularly early in Lyme disease. Therefore, a negative result does not exclude the diagnosis early in the course of the illness (7). Antimicrobial therapy with oral tetracycline is recommended for patients with early manifestations of Lyme disease; penicillin and erythromycin are also effective (8). Children and pregnant women should be treated with penicillin. Some of the neurologic abnormalities, as well as established arthritis, have been found to respond to high dose intravenous penicillin (9,10).

Previously, Lyme disease was recognized in three endemic areas: the coastal areas of the northeast (Connecticut, Delaware, Maryland, Massachusetts, New York, New Jersey, Pennsylvania, Rhode Island), the midwest (Minnesota, Wisconsin), and the west (California, Nevada, Oregon, Utah). Although these areas are within the range of the known tick vectors, I. dammini and I. pacificus, some areas where Lyme disease has occurred are not. However, B. burgdorferi has been found in Amblyomma americanum (11) and Dermacentor variabilis; these and other ticks may be vectors in some areas.

It is not known to what extent the increase in numbers and widening geographic distribution of cases reflect increased recognition or reporting rather than increased incidence of the disease or spread of the vectors and/or spirochete. Increased reporting is probably responsible for part of the greater than 500% increase in reported cases in Connecticut in 1984, because an active surveillance system was initiated in the state that year. Underreporting is suspected in some states, such as Massachusetts, where officials think far greater numbers of cases are occurring than are reported. CDC encourages reporting of cases of Lyme disease to state and local health departments so the geographic distribution and temporal trends can be better defined.

Since transplacental transmission of B. burgdorferi has been documented, it will be important to determine whether maternal infection with B. burgdorferi is associated with an increased risk of adverse pregnancy outcome. Cases of Lyme disease during pregnancy should be reported to state health departments and CDC (telephone (404) 329-3687) before delivery so the types and approximate frequency of any adverse outcome can be determined and appropriate diagnostic tests obtained.


  1. Schlesinger PA, Duray PH, Burke BA, et al. Maternal-fetal transmission of the Lyme disease spirochete, Borrelia burgdorferi. Ann Intern Med 1985 (in press).

  2. Steere AC, Malawista SE, Syndman DR, et al. Lyme arthritis: an epidemic of oligoarticular arthritis in children and adults in three Connecticut communities. Arthritis Rheum 1977;20:7-17.

  3. Steere AC, Grodzicki RL, Kornblatt AN, et al. The spirochetal etiology of Lyme disease. N Engl J Med 1983;308:733-40.

  4. Johnston YE, Duray PH, Steere AC. Lyme arthritis: spirochetes found in synovial microangiopathic lesions. Am J Pathol 1985;118:26-34.

  5. Craft JE, Grodzicki RL, Steere AC. Antibody response in Lyme disease: evaluation of diagnostic tests. J Infect Dis 1984;149:789-95.

  6. Russell H, Sampson JS, Schmid GP, Wilkinson HW, Plikaytis B. Enzyme-linked immunosorbent assay and indirect immunofluorescence assay for Lyme disease. J Infect Dis 1984;149:465-70.

  7. Shrestha M, Grodzicki RL, Steere AC. Diagnosing early Lyme disease. Am J Med 1985;78:235-40.

  8. Steere AC, Hutchinson GJ, Rahn DW, et al. Treatment of the early manifestations of Lyme disease. Ann Intern Med 1983;99:22-6.

  9. Steere AC, Green J, Schoen RT, et al. Successful parenteral penicillin therapy of established Lyme arthritis. New Engl J Med 1985;312:869-74.

  10. Steere AC, Pachner AR, Malawista SE. Neurologic abnormalities of Lyme disease: successful treatment with high-dose intravenous penicillin. Ann Intern Med 1983;99:767-72.

  11. Schulze TL, Bowen GS, Bosler EM, et al. Amblyomma americanum; a potential vector of Lyme disease in New Jersey. Science 1984;224:601-3.

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