LYME DISEASE RISK ASSESSMENT, WOODBRIDGE RESEARCH FACILITY, ADELPHI LABORATORY CENTER, ADELPHI, MARYLAND, 1991 and 1992 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) 22 JUL 1992 LYME DISEASE RISK ASSESSMENT NO. 16-61-A846-92 WOODBRIDGE RESEARCH FACILITY, ADELPHI LABORATORY CENTER ADELPHI, MARYLAND 23 AND 30 NOVEMBER, 7, 14, 21 AND 28 DECEMBER 1991, AND 4 JANUARY 1992 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. 2. AUTHORITY. a. AEHA Form 250-R, 26 June 1991. b. Conference Report on the National Defense Authorization Act for Fiscal Years 92 and 93, House Report 102-311, 102nd Congress, 1st Session, November 1991, p. 422. 3. PURPOSE. To assess the risk of Lyme disease to Adelphi Laboratory Center personnel at the Woodbridge Research Facility (WRF), Woodbridge Virginia, 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: (1) History of Lyme disease in the area. (2) The presence or absence of the tick vector (I. dammini) and the mammalian host population needed to sustain a viable population of the vector. (3) The presence of the Lyme disease-causing spirochete (B. burgdorferi) in the tick population or the mammalian reservoir host population. (4) The presence of antibodies to B. burgdorferi in the mammalian 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. Mr. Robert Wardwell, Natural Resources Manager, and Ms. Faith Hoetzer, RN, Occupational Health Nurse, both of the U.S. Army Adelphi Laboratory Center, and Dr. Margie Benko, DVM, Epidemiologist, Virginia State Health Department. c. Survey Conduct. The field survey was conducted by Karl Neidhardt, Entomologist, U.S. Army Environmental Hygiene Activity - North (USAEHA-North), Fort George G. Meade (FGGM), Maryland, on 23 November 1991. Follow-up samples were collected by Mr. Robert Wardwell on, 30 November, 7, 14, 21, and 28 December, 1991 and 4 January, 1992. Serum samples were assayed via Indirect Fluorescent Antibody (IFA) tests by personnel of the U.S. Army Regional Veterinary Laboratory, FGGM, Maryland for the presence of antibody to the Lyme spirochete. Ticks were identified and assayed via Direct Fluorescent Antibody (DFA) tests by personnel of USAEHA-North, FGGM, Maryland for the presence of B. burgdorferi. d. Technical Assistance. Technical assistance or further informal advice may be obtained by contacting Chief, 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 71 hunter-shot white-tailed deer (Odocoileus virginianus) were examined immediately before or after the weigh in and tagging at the WRF, deer check station. The deer hair was stroked contrary to the natural lay, using the hand to expose the skin. Ticks were removed, using fine-point (No. 5) jeweler's forceps, from the head, ears or neck of the 71 animals examined. Total examination time-per-carcass was approximately 5 minutes. Collected ticks were placed in labeled, 20 ml humidified vials and kept cool (1.5 - 4.5 degrees C). b. Tick Testing. Ticks were assayed via DFA testing using antibody conjugate from Kirkegaard and Perry Laboratories, to determine presence of the Lyme disease spirochete, B. burgdorferi. This conjugate is affinity absorbed to minimize cross reactivity with other spirochetes. c. Blood Samples. Blood pooled in the body cavities of 71 hunter-shot deer was collected using clean plastic (4ml) 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 Enclosure 1) a. A total of 240 ticks were collected from 71 deer examined at WRF, 167 were I. dammini. Thirty-four (48 percent) of the 71 deer examined, were infested with the deer tick, I. dammini. A total of 196 ticks were tested with 18 (9 percent) positive for spirochetes. Of the positive ticks, 11 were I. dammini, 3 were Dermacentor albipictus and 4 were Amblyomma americanum. b. Of the 71 serum samples collected and tested, 4 (6 percent) were positive (greater than 1:128 titer level) for antibodies to Lyme disease. c. Epidemiological data for 1991 from the Virginia State Health Department reports 22 confirmed human cases of Lyme disease in Prince William County, where WRF is located. In 1991 there were 2 cases in nearby King George County and 151 human cases statewide. 7. DISCUSSION. This survey provides evidence that the tick vector and the Lyme disease spirochete are established at WRF. Participants in outdoor and natural resources activities are all at risk for contracting Lyme disease at WRF. This information combined with historical evidence of Lyme disease in the surrounding area and environmental conditions necessary for the occurrence of Lyme disease, all make WRF an area warranting continued vigilance. 8. CONCLUSIONS. The presence of specimens of I. dammini on examined deer, and information from the Virginia State Health Department on the epidemiology of Lyme disease in Prince William County and surrounding areas, indicates that the present risk of contracting human Lyme disease at the Woodbridge Research Facility is Moderate. 9. RECOMMENDATIONS. a. Implement contingency planning in accordance with guidelines in Enclosure 2. b. Conduct annual follow-up surveillance using the methods described in reference 1.b and para 5 above. Provide continued monitoring and note changes in the degree of Lyme disease threat to WRF personnel. [signature of Benedict B. Pagac, Jr.] for KARL F.E. NEIDHARDT, BCE Entomologist Entomological Sciences Division APPROVED BY: [signature] GEORGE J. MAGNON CPT, MS Chief, Entomological Sciences Division Enclosure 1 DOD LYME DISEASE SURVEY U.S. ARMY ENVIRONMENTAL HYGIENE ACTIVITY-NORTH DATA SUMMARY - FALL/WINTER 1991-1992 INSTALLATION Adelphi Laboratory Center, Woodbridge Research Facility SURVEY DATES 23 and 30 November, 7, 14, 21, 28 December, 1991 and 4 January, 1992. # OF DEER EXAMINED 71 # (%) DEER WITH Ixodes dammini 34 (48%) # DEER SERUM SAMPLES TESTED 71 # DEER SERUM SAMPLES POSITIVE * 4 (6%) TICK SPECIMENS ----------------------------------- # COLLECTED # TESTED # POSITIVE Ixodes dammini ** 167 149 11 (7%) Dermacentor albipictus 27 14 3 (21%) Amblyomma americanum 46 33 4 (12%) --------------------------------- TOTAL TICKS 240 196 18 (9%) * positive screening titer levels greater than 1:128 ** Ixodes dammini vs. Ixodes scapularis determination in adult ticks is difficult. However, random samples of adult specimens from installations as far south as Virginia and North Carolina 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 presence of the pathogen. 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