LYME DISEASE RISK ASSESSMENT, GUNPOWDER MILITARY RESERVATION, GLEN ARM, MARYLAND, 12-15 MAY AND 8-9 JULY 1992 DEPARTMENT OF THE ARMY U.S. Army Environmental Hygiene Agency Aberdeen Proving Ground, Maryland 21010-5422 [Seal of Department of Defense, United States of America] REPLY TO ATTENTION OF: HSHB-MR-E 03 AUG 1992 LYME DISEASE RISK ASSESSMENT NO. 16-44-AL11-92 GUNPOWDER MILITARY RESERVATION GLEN ARM, MARYLAND 12-15 MAY AND 8-9 JULY 1992 1. REFERENCES. a. AR 40-5, 15 October 1990, Preventive Medicine. b. AR 420-76, 3 July 1986, Pest Management Program. c. Memorandum, USAEHA, 9 April 1992, subject: Lyme Disease Risk Assessment, Gunpowder Military Reservation, Maryland, Project No. 16-44-AL11-92. 2. AUTHORITY. AEHA Form 250-R, NGB, 5 August 1991. 3. PURPOSE. To evaluate the risk of Lyme disease to personnel training at Gunpowder Military Reservation (GPMR), by dragging vegetation and examining white-footed mice for the tick vector, Ixodes dammini, and assay collected ticks for the etiologic agent, Borrelia burgdorferi. 4. GENERAL. a. Personnel Contacted. CW4 John Elwood, Training Site Administrator, Director of Plans Operations and Training, 5th Regiment Armory and Mr. Dick Jordon, Reservation manager, Gunpowder Military Reservation, Glen Arm, Maryland. b. Survey Performance. The field survey was conducted by 1LT Sandra Alvey, Entomologist; CPL Jemal Wafford, and SPC James Richardson, Entomological Sciences Division of this agency, on 12-15 May 1992 and 8-9 July 1992. c. Survey Site. The GPMR is located in Maryland, approximately 3 miles northeast of Parkville, in Baltimore County. The terrain is hilly, with some areas of heavy undergrowth. The installation supports year-round field training exercises for not only the National Guard and Reserves, but also active duty soldiers from Aberdeen Proving Ground located in Harford county and ROTC units from nearby colleges and universities. d. Technical Assistance. Technical assistance or further informal advice may be obtained by contacting the Entomological Sciences Division (ESD), USAEHA, Commercial Phone 410-671-3613, (DSN 584-3613). 5. METHODS. 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, and the presence of B. burgdorferi or antibodies to Lyme disease in the tick population or mammal host population respectively. Criteria for risk categorization follows: 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. Tick Collection. Sherman live capture traps baited with a peanut butter and oatmeal mixture were placed in wooded areas. The areas selected had been identified as the best woodland mouse habitats for small mammal surveys. During the period of 12-15 May a total of 150 traps were set overnight for three consecutive nights. In addition, 75 traps were set out overnight on 8 July. Mice captured were taken indoors, anesthetized, and examined under a dissecting microscope for ectoparasites. Following examination, mice were returned to the capture location and were released. During examination hair was stroked contrary to the natural lay, and ticks were removed by using fine-point (No. 5) jeweler's forceps. Collected ticks were placed in labeled, 20 ml humidified vials and kept cool (1.5 - 4.5 C). Ticks were also collected off of vegetation using a white flannel drag cloth mounted on a dowel. The cloth was checked every 10 meters for tick removal, while dragging was done in 100 meter increments. Approximately 5400 meters were dragged. Ticks were returned to USAEHA for identification and testing. c. Tick Assays. Ticks were assayed via Indirect Fluorescent Antibody (IFA) testing using a monoclonal antibody (H5332) from Kirkegaard and Perry Laboratories, Inc. and a Fluorescien Labeled (FITC) antibody to determine infection rates of the Lyme disease spirochete, B. burgdorferi. 6. RESULTS. a. A total of eight ticks were removed from cloth drags during the period of 12-15 May 1992. Six of the ticks were identified as I. dammini nymphs and two were I. dammini adult males. All were found to be negative for the Lyme disease spirochete, B. burgdorferi. b. No mice were captured during the period of 12-15 May 1992 and of the two mice captured on 8 July 1992, neither had ticks on them. c. There have been no reports of human Lyme disease at GPMR. d. Maryland Department of Health and Mental Hygiene reports 39 cases of human Lyme disease in Baltimore County and 27 cases in Harford County for 1990, thus one would expect personnel training at GPMR to be at risk for Lyme disease. 7. DISCUSSION. This survey provides no evidence that the vector and causative agent of Lyme disease are established at GPMR. However, several risk factors are present at GPMR or in the immediate area. These include: historical evidence of the presence of Lyme disease and its vector in the immediate areas and surrounding counties; there is a potential at-risk human population (troops in field training); previously known availability of suitable animal hosts (mice and deer), and environmental conditions necessary for the occurrence of Lyme disease. The presence of these factors make GPMR an area warranted for continued Lyme disease surveillance. 8. CONCLUSIONS. The low number of I. dammini collected by the drag technique, the absence of ticks on white-footed mice and negative IFA results, from the May and July 1992 surveys, would indicate low risk of contracting human Lyme disease at GPMR. However, the incidence of human Lyme disease cases in Baltimore and Harford counties would indicate that the present risk of contracting human Lyme disease is Moderate. 9. RECOMMENDATIONS. The moderate risk category dictates action. The documented spread of Lyme disease into new regions from neighboring endemic areas support contingency planning to reduce future risk to GPMR personnel. a. Implement contingency planning in accordance with guidelines 1-4 in Appendix A. b. Emphasize public awareness programs, for example: distribution of Lyme disease handouts, making available for viewing, the video, "LYME DISEASE: A growing threat" (FAUPIN No. 504494DA), and Technical Guide 174, Personal Protection. All of these resources can be obtained from this agency upon request. [signature] SANDRA L. ALVEY 1LT, MS Entomologist Entomological Sciences Division APPROVED: [signature] RICHARD D. WELLS Program Manager, Pest Management Entomological Sciences Division APPENDIX A Lyme Disease Risk Reduction Measures 1. Emphasize public awareness programs to educate troops, family members, civilian employees and visitors on personal protective measures and Lyme disease. Methods should include, but not be 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-September). c. Making available, for viewing, videos "Lyme Disease: A growing threat" (FAUPIN No. 504494DD, Army TVT number 8-196) and "Application of the Arthropod Repellent System" (No. 708575, Army TVT number 8-232). 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 Meade, Maryland, 20755-5225. 3. Stock Permethrin Arthropod Repellent (NSN 6940-01-278-1336, 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, 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)] by special telegraphic report [MED-16(R4)] for all soldiers and civilian medical care beneficiaries. 5. 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, to 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