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Lyme disease is a spirochetal infection endemic throughout New Jersey. Case reports from 1984 through 1986 suggest different high-risk groups and different disease severity than had been observed in earlier cases in the state. Both sexes now appear equally at risk, while younger age groups, particularly children less than ten years old, appear to be at increased risk. Mild disease is usual, although classic rheumatologic and neurologic complications can occur. Informal surveys suggest Lyme disease is under-reported by a factor of five- to tenfold in New Jersey. Early recognition by physician and patient is necessary for prompt treatment to reduce complications.

Epidemiological investigations were initiated in 1984 when significant Lyme disease activity was observed within a 5-km radius of an area previously used as a non-endemic control site for Lyme disease research in New Jersey. Through 1983, collections of Ixodes dammini from vegetation and feral rodents were infrequent and no human cases were identified within a 16-km radius of the control site. In 1984, 4 human cases and 3 serologically reactive canines (greater than or equal to 1:512) were recognized within the area and adult I. dammini populations were over 3-fold greater than those at our primary study location where Lyme disease has been endemic since 1981. Using darkfield microscopy, 53.4% of adult I. dammini were infected with Borrelia burgdorferi as compared to 50.0% of adults collected during the same period at the known endemic study site. These data indicate that a focus of Lyme disease has recently become established at the previously non-endemic control site and that the establishment of new foci may occur more rapidly than once thought.

Although many aspects of Lyme disease have been intensely studied for over a decade, little research has been directed toward control of the principal tick vector, Ixodes dammini. Ecological and epidemiological investigations have provided not only an ample understanding of tick biology and behavior, they have also identified the types of areas at risk for disease transmission. The advantages and limitations of previous attempts to control I. dammini by host reduction, habitat modification, and acaricide applications have been discussed in relation to overall control strategies for high-risk areas, and an integrated approach to control proposed.

As part of continuing studies of Lyme disease, deer were surveyed during three hunting seasons in 1981 to obtain information on geographic distribution and density of I. dammini in New Jersey. I. dammini occurred throughout central and southern New Jersey. Four deer management zones (DMZs) were shown to have high tick densities. Geographical distribution and density data were independently regressed against 25 environmental and physical factors. Elevation was shown to be the most important factor in explaining the variability in both I. dammini distribution and density. Lyme disease cases were closely associated with the distribution of I. dammini and 57.3 percent of 117 Lyme disease cases occurred in the four DMZs previously identified as having the highest tick density.

From August 1984 through February 1985, 423 dogs from 43 municipalities in 7 New Jersey counties were evaluated for the presence of antibodies to the Lyme disease spirochete (Borrelia burgdorferi). Of these dogs, 34.7% with no apparent clinical symptoms were serologically reactive (IFA greater than or equal to 1:64); titers in this study ranged from non-reactive to 1:2048. Ninety percent of the dogs surveyed had a current vaccination status to Leptospira interrogans serovars canicola and icterohaemorhagiae. Dogs vaccinated to leptospirosis elicited homologous antibody titers of less than or equal to 1:16 and, therefore, did not interfere with interpretation of antibody levels to B. burgdorferi. Effects of age, degree of outdoor activity, travel history, and location of residence were evaluated. The use of serosurveys of dogs as a tool for Lyme disease surveillance is discussed.