LYME DISEASE RISK ASSESSMENT, FORT DIX, NEW JERSEY, 28 DECEMBER 1991 DEPARTMENT OF THE ARMY U.S. Army Environmental Hygiene Activity - North Fort George G. Meade, Maryland 20755-5225 [Seal of Department of Defense, United States of America] REPLY TO ATTENTION OF: HSHB-AN-P (40-5) 15 APR 1992 LYME DISEASE RISK ASSESSMENT NO. 16-61-A848-92 FORT DIX, NEW JERSEY 9, 10, 28 DECEMBER 1991 1. REFERENCES. a. Lyme Disease Surveillance Summary, Vol. 3, No. 1, Centers for Disease Control, March 1992. b. Technical Information Memorandum No. 26, Lyme Disease: Vector Surveillance and Control. Armed Forces Pest Management Board, March 1990. c. AR 40-5, Preventive Medicine, 15 October 1990. 2. AUTHORITY. AEHA Form 250-R, HSC, 7 August 1991. 3. PURPOSE. To assess the risk of Lyme disease to Fort Dix personnel by examining white-tailed deer for the tick vector, Ixodes dammini, and to assay collected ticks for the Lyme disease etiologic agent, Borrelia burgdorferi. 4. GENERAL. a. Risk Definition. The term "risk", as used in this report, is a nonstatistical evaluation of qualitative and quantitative information available to determine the potential to acquire Lyme disease. To the extent available, information evaluated includes the following elements: Past history of Lyme disease in the area, the presence or absence of the tick vector and the mammalian host population needed to sustain a viable population of the vector, the presence of B. burgdorferi in the tick population or the presence of antibodies to B. burgdorferi in the mammal host population. Criteria for risk categorization follow: Low risk - Some elements of the Lyme disease cycle identified in nearby areas but not on the installation. Moderate risk - Elements of Lyme disease cycle identified from the installation or human cases of Lyme disease reported from the local area. High risk - All elements of the Lyme disease cycle present on the installation. b. Personnel Contacted. Captain Daniel Cunningham, Environmental Science Officer, Preventive Medicine Service, U.S. Army Medical Department Activity, Fort Dix. c. Survey Conduct. The Field survey was conducted by CPT Daniel Cunningham and CPT Thomas Burroughs, this Activity, on 9 and 10 December 1991. Additional ticks and serum samples were collected on 28 December by CPT Cunningham. Serum samples were assayed via Indirect Fluorescent Antibody (IFA) tests by personnel of the U.S. Army Regional Veterinary Laboratory, Fort George G. Meade, Maryland, for the presence of Lyme disease antibody. Ticks were identified and assayed via Direct Fluorescent Antibody (DFA) tests by personnel of this Activity for the presence of B. burgdorferi. d. Technical Assistance. Technical assistance or further informal advice may be obtained by contacting the Entomological Sciences Division (ESD), USAEHA-North, Commercial Phone 410-677-5281/6502, (DSN 923-5281/6502). 5. METHODS. a. Tick Collection. The head, ears, and neck of 42 hunter-shot white-tailed deer (Odocoileus virginianus) were examined immediately before or after the weigh in and tagging at the Fort Dix deer check station. The deer hair was stroked contrary to the natural lay, using the hand to expose the skin. If no ticks were observed on the head, ears or neck of the animals examined, additional time was spent looking for ticks on other regions of the deer carcass. Total examination time-per-carcass was between 5 and 10 minutes. b. Blood Samples. Blood pooled in the body cavities of 42 hunter-shot deer was collected using clean plastic (4 ml) disposable pipettes. Blood samples were not taken from carcasses that were rinsed with water or otherwise treated in a manner which might contaminate or invalidate the sample. Samples were placed in 7 ml labeled tubes, spun, sera were collected, and frozen (-8.5 degrees C) until IFA testing could be performed. 6. RESULTS. (See also Enclosure 1) a. Ixodes dammini were found on all 42 deer examined. b. Thirty-one percent of the Ixodes dammini and 25 percent of the total number of ticks tested were positive for the spirochete causing Lyme disease. c. Seven serum samples tested from 42 deer were positive (greater than 1:128 titer level) for Lyme disease antibody. d. The Center for Disease Control reports 852 cases of Lyme disease in New Jersey for 1991. 7. DISCUSSION. Fort Dix has a well established Lyme disease record and an on-going prevention program and high command interest. It is tied for second highest in cases reported to the Office of the Army Surgeon General, among DOD installations listed as the source of human infection. The area where Fort Dix is located is considered to be a hyper-endemic area for Lyme disease by Lyme disease professionals. In a previous survey conducted by this Activity in 1990, 48 percent of 354 ticks tested were positive for B. burgdorferi. This is in keeping with expected tick infection rates in hyper-endemic areas. The somewhat depressed, 31 percent tick infection rate noted in this survey may not be representative and warrants continued surveillance in light of historical information. There is no corroborating evidence for New Jersey indicating a real decreasing Lyme disease threat. The Center for Disease Control reports 852 confirmed cases of Lyme disease for New Jersey in 1991, down approximately 200 cases from 1990. Continued surveillance and prevention programs are needed to determine if the decline from 1990 to 1991 is real or only a statistical fluctuation. 8. CONCLUSION: The preponderance of information available indicates that the present risk of contracting Lyme disease at Fort Dix is high. The potential at-risk human population (those engaged in field training, natural resources activities etc.), along with availability of suitable animal hosts and environmental conditions, makes Fort Dix an area warranting the use of protective measures and continued vigilance. 9. RECOMMENDATIONS. The high risk category and conditions at Fort Dix dictate the need for continued prevention programs and increased surveillance. a. Continue existing efforts, programs and plans in accordance with guidelines in Enclosure 2. b. Conduct follow-up surveillance using the methods described in reference 1.b and para 5, above, on an annual schedule. Provide continued monitoring and note changes in the degree of Lyme disease threat to Fort Dix personnel. [signature of James T. Kardatzke] for THOMAS M. BURROUGHS CPT, MS Entomologist APPROVED BY: [signature] JAMES T. KARDATZKE, PhD, BCE MAJ, MS Chief, Entomological Sciences Division Enclosure 1 DOD LYME DISEASE SURVEY U.S. ARMY ENVIRONMENTAL HYGIENE ACTIVITY-NORTH DATA SUMMARY - FALL/WINTER 1991 INSTALLATION Fort Dix, New Jersey SURVEY DATE(S) 9, 10, 28 December 1991 # OF DEER EXAMINED 42 # (%) DEER EXAMINED WITH Ixodes dammini 42 (100%) # DEER SERUM SAMPLES TESTED 42 # DEER SERUM SAMPLES POSITIVE * 7 (17%) TICK SPECIMENS ----------------------------------- # COLLECTED # TESTED # POSITIVE Ixodes dammini ** 719 386 118 (31%) Dermacentor albipictus 141 112 15 (13%) Amblyomma americanum 37 30 1 (3%) --------------------------------- TOTAL TICKS 897 528 134 (25%) * positive screening titer levels (greater than 1:128) for Lyme antibody ** Ixodes dammini vs. Ixodes scapularis determination in adult ticks is difficult. However, samples of adult Ixodes specimens from Fort Dix were all identified as I. dammini by The Curator of Ticks, U.S. National Tick Collection, at the Institute of Arthropodology and Parasitology at Georgia Southern University. Enclosure 2 Lyme Disease Risk Reduction Measures 1. Emphasize public awareness programs to educate troops, dependents, civilian employees and visitors on personal protective measures and Lyme disease. Methods should include, but are not limited to: a. distribution of printed Lyme disease handouts, such as tick identification cards (USAMD-7/89), pamphlets, and fact sheets. b. notifications in the installation newsletter and post electronic media (e.g., closed-circuit TV), especially prior to the high-risk months (May-November). c. making available, for viewing, the video LYME DISEASE: A growing threat (FAUPIN No. 504494DA). 2. Submit any collected tick specimens (both field-collected or ticks that have been removed from individuals) alive for identification and DFA testing to USAEHA-North, Fort George G. Meade, MD, 20755-5225. 3. Stock Permethrin Arthropod Repellent (NSN 6840-01-278-1336, box of 12 cans for $36.99), and 3M [Trademark] Insect Repellent (NSN 6840-01-284- 3982, box of 12 tubes, $29.30) for distribution. Emphasize tick habitat avoidance and the proper wearing of clothing and use of repellents. 4. Report all confirmed and suspected cases of Lyme disease [e.g., suspicious febrile illnesses, arthralgias, rashes, (Erythema Migrans)] to the appropriate medical authority for all military personnel and civilian beneficiaries. 5. Perform deer check surveillance to monitor adult tick presence and the presence of pathogens. Identify high risk foci in cantonment areas via tick dragging/flagging, small mammal trapping, deer checks and the assaying of collected ticks for B. burgdorferi. Sampling should be performed in early summer when I. dammini nymphs (the life stage responsible for most human Lyme disease infections) are active. Post DA Poster 40-5 (or equivalent), and thereby identify high risk areas. 6. Avoid high tick population areas for troop training or recreation. Such areas can be identified by tick dragging or flagging prior to use. Case by case surveillance is necessary due to the patchy distribution of I. dammini. 7. Eliminate tick habitat in heavily used, infested areas (e.g., wooded recreation areas) by removing low brush and leaf litter. Tick infestations should be verified via tick flagging or dragging prior to habitat modification. Clearing should be done in low risk months (i.e., January and February). 8. Prepare, as a contingency, to treat high-use areas with pesticides to decrease tick numbers if surveillance reveals high tick numbers and if nonchemical control techniques (e.g., brush removal, mowing, raking) do not provide adequate control. --- Trademark 3M is a registered trademark of Minnesota Mining and Manufacturing Co., St. Paul, MN 55133-3053