LYME DISEASE RISK ASSESSMENT, UNITED STATES MILITARY ACADEMY, WEST POINT, NEW YORK, 15-18 JUNE 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 (40-5f) 10 SEP 1992 LYME DISEASE RISK ASSESSMENT NO. 16-61-A851-92 UNITED STATES MILITARY ACADEMY WEST POINT, NEW YORK 15-18 JUNE 1992 1. REFERENCES. a. Lyme Disease Surveillance Summary, Volume 3, No. 1, March 1992, Centers for Disease Control. b. Burt, W. H. and R. P. Grossenheider, A Field Guide to the Mammals North America north of Mexico, Third Edition, 1976, Houghton Mifflin Company, Boston, 289 pp. c. Installation Pest Profile No. 16-61-0555-90, United States Military Academy, West Point, New York, 27 March-13 November 1989. d. AFPMB Technical Information Memorandum No. 26, Lyme Disease Vector Surveillance Control, March 1990. 2. AUTHORITY. a. Conference Report on the National Defense Authorization Act for Fiscal Years 92 and 93, House Report 102-311, 102nd Congress, 1st Session, 13 November 1991, p.422. b. USAEHA Form 250-R, HSC, 7 August 1991. 3. PURPOSE. To assess the risk of Lyme disease to United States Military Academy (USMA) personnel by examining rodents for the tick vector, Ixodes dammini and to assay collected ticks for the Lyme disease causative agent, Borrelia burgdorferi. 4. GENERAL. a. Risk definition. The term "risk", as used in this report, is a non-statistical 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. Risk categorization criteria are: Low risk - Some risk elements identified in nearby areas but not on the installation. Moderate risk - Some risk elements identified from the installation or human cases of Lyme disease reported from the local area. High risk - All risk elements present on the installation. b. Personnel Contacted. (1) The purpose and methodology of this assessment were discussed with LTC Heiko Volkmann, Chief, Veterinary Services, USMA. (2) Dr. Dennis White, Branch of Communicable Disease, New York State Department of Health, was contacted for Lyme disease statistics. c. Survey Conduct. First Lieutenant Jamie A. Blow, Entomologist, this Activity; SPC Barbara Cyrus, Preventive Medicine Specialist, this Activity; and PFC Kathy Erlund, Preventive Medicine Specialist, Veterinary Services, USMA conducted this assessment. 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 Chief, Entomological Sciences Division (ESD), this Activity, Commercial Phone (410)-677-5281/6502 or DSN 923-5281/6502. 5. BACKGROUND. a. Lyme disease is a multi-systemic infectious disease caused by the spirochete, B. burgdorferi, which is transmitted to humans by the bite of an infected tick. The disease is most often referred to as Lyme disease or Lyme arthritis in the United States. Lyme disease has become the most prevalent arthropod-borne illness in North America. Its geographic range is expanding and the number of reported cases continues to rise each year. The Office of the Surgeon General reported 379 cases of Lyme disease contracted on Department of Defense (DOD) installations from 1987 through 1991. During 1990, there were 78 cases of Lyme disease treated in military hospitals from all the Armed Services of which 26 of the cases were either dependents or retired members. During 1991, there were 81 cases of Lyme disease treated in miltary hospitals of which 31 of the cases were either dependents or retired members. Three soldiers were reported to have permanent disabilities caused by Lyme disease during 1991. The need to protect soldiers and other personnel working on DOD installations has increased with the spread of Lyme disease. b. In 1991, the State of New York Department of Health reported 3,811 cases of Lyme disease statewide that meet the Centers for Disease Control (CDC) guidelines. There were 40 reported cases meeting CDC guidelines in 1991 in Orange County where USMA is located. c. In an Installation Pest Profile (Reference c) performed by this Activity in 1989, 32 I. dammini ticks were collected for analysis. All were negative for the Lyme Disease organism, B. burgdorferi. d. United States Military Academy is located on the west bank of the Hudson River in the southeastern corner of Orange County. United States Military Academy contains housing, training, and recreational areas. 6. METHODS. a. Survey Procedures. (1) Tick Surveys. Ticks were collected using tick drags and from the ears and bodies of trapped rodents. (a) Tick Drag Technique. Two narrow boards (1X2X36-inch) were attached on opposite ends of a 3X3-foot white flannel cloth. A cord was fastened to the ends of one board. The cloth was then pulled slowly over vegetation for approximately 10 meters before examination for attached ticks. This procedure was repeated 10 times at the Lake Frederick bivouac area. Any ticks collected were removed from the cloth and placed in a 20 ml humidified vial, labeled for that particular dragging operation, and kept cool. (2) Rodent Trapping. Small mammals were captured in live traps. Nine trapping locations were selected at USMA and two trap lines were set at each location. Traps were located near brush piles, downed logs, rock walls, rocks, and anywhere else offering harborage for rodents. Rodents trapped at USMA were identified using "A Field Guide to the Mammals of North America, North of Mexico", (Reference b). All animals were anesthetized with ketaset before removing ticks. All animals were examined with dissecting microscope for ticks. Ticks found on animals were removed, using fine-point (No. 5) jeweler's forceps and were retained for bioassay. Collected ticks were placed in labeled, 20 ml humidified vials and kept cool. (3) Laboratory Assay Procedures. Ticks were assayed via DFA testing using antibody conjugate from Kirkegaard and Perry Laboratories, Inc. to determine presence of the Lyme disease spirochete, B. burgdorferi. This conjugate is affinity absorbed to minimize cross reactivity with other spirochetes. 7. RESULTS. (See also Appendix A). a. Trapping success was high with a total of 79 White-footed mice (Peromyscus leucopus) and 1 Fox Squirrel (Sciurus niger) captured. A total of 12 ticks (1 Ixodes angustus and 11 Dermacentor variabilis) were collected from 12 of the 79 (15 percent) mice. No ticks were collected on area drags. b. Spirochetes indicative of Lyme disease were observed by DFA staining in 1 of 11 (9 percent) D. variabilis. However, D. variabilis has not been implicated in the transmission of Lyme disease. No spirochetes were observed in the 1 I. angustus. c. Areas trapped include bivouac areas, range, training and recreational sites. Dragging was done at the Lake Frederick bivouac area with no ticks collected. 8. CONCLUSIONS. While previously collected, the Lyme disease tick vector, Ixodes dammini, was not collected at USMA during this Survey. Spirochetes indicative of B. burgdorferi, the causative agent for Lyme disease, were found in 1 of 11 (9 percent) D. variabilis ticks, collected from the USMA. Orange County, where USMA is located, reported 40 confirmed cases of Lyme disease in 1991. This information indicates that the present risk of acquiring Lyme disease at USMA is MODERATE. Implementation of personal protective measures for all military and civilians using USMA for training, bivouac, and recreation is recommended. 9. RECOMMENDATIONS. The moderate risk category and conditions at USMA dictate the need for continued prevention programs and increased surveillance. a. Implement guidelines in Appendix B. The risk of contracting Lyme disease can be minimized by the proper wearing of clothing, by avoiding areas known to harbor high tick populations, and by the proper use of repellents. (See Appendix C for repellent products available in the Defense General Supply Center or Self Service System). b. Conduct annual follow-up surveillance using the methods described in reference d (TIM 26) and para. 6 this report. [signature of Karl Neidhardt] for JAMIE A. BLOW 1LT, MS Entomologist APPROVED BY: [signature] GEORGE J. MAGNON CPT(P), MS Chief, Entomological Sciences Division APPENDIX A DOD LYME DISEASE SURVEY U.S. ARMY ENVIRONMENTAL HYGIENE ACTIVITY-NORTH DATA SUMMARY Table 1. Ticks collected from animal hosts, West Point, New York, 15-18 JUNE 1992. =========================================================================== Host #Hosts Ticks ---------------------------------------------------- I. angustus D. variabilis Total Stage C / T / P / %(1)C / T / P / % C / T / P / % --------------------------------------------------------------------------- larva none 11 /11 / 1 / 9 11 /11 / 1 / 9 White-footed Mouse ---------------------------------------------------- P.leucopus 79 nymph 1 / 1 / 0 / 0 none none ---------------------------------------------------- adult none none 1 / 1 / 0 / 0 --------------------------------------------------------------------------- larva none none none Fox Squirrel ---------------------------------------------------- S. nigra 1 nymph none none none ---------------------------------------------------- adult none none none --------------------------------------------------------------------------- Total 80 all 1 / 1 / 0 / 0 11 /11 / 1 / 9 12 /12 / 1 / 8 --------------------------------------------------------------------------- Table 2. Ticks collected from habitat surveys, West Point, New York, 16-18 JUNE 1992. =========================================================================== Host #Hosts Ticks ---------------------------------------------------- I. angustus D. variabilis Total Stage C / T / P / %(1)C / T / P / % C / T / P / % --------------------------------------------------------------------------- larva none none none ---------------------------------------------------- Drag 10 nymph none none none ---------------------------------------------------- adult none none none --------------------------------------------------------------------------- Total 10 all none none none --------------------------------------------------------------------------- (1) C / T / P / % = # Collected / # Tested / # Positive / % Positive for spirochetes. APPENDIX B 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's newsletter and post electronic media (e.g., closed-circuit TV), especially prior to the high-risk months (May-November). c. Making available, for viewing, video Lyme Disease: A growing threat (FAUPIN No. 504494DA). A 35 mm slide format presentation on Lyme disease is also available from this Activity. 2. Submit any collected tick specimens (both field-collected or ticks that have been removed from individuals) alive for identification and DFA testing to the Entomological Sciences Division (ESD), U.S. Army Environmental Hygiene Activity-North (USAEHA-North), Building 4411, Fort George G. Meade, MD 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 and 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 message using the Disease Alert Report Format for all soldiers and civilian 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 Borrelia burgdorferi. Sampling should be performed in early summer when Ixodes dammini nymphs (the life stage responsible for most human Lyme disease infections) are active. Post DA Poster 40-5, and thereby identify high risk areas. DA Poster 40-5 can be obtained by writing to the Commander, U.S. Environmental Hygiene Agency, ATTN: HSHB-MR-E, Aberdeen Proving Ground, MD 21010-5422 or by telephone: DSN 584-3613 or Commercial (410) 671-3613. 6. Avoid high tick population areas for troop training or recreation. Such areas can be identified by dragging or flagging for ticks 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. 8. Prepare, as a contingency, to treat high-use areas with pesticides 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 APPENDIX C REPELLENTS 1. Several repellent products are available through the Defense General Supply Center (DGSC) or Self Service Supply System. When used in accordance with label directions and in conjunction with the proper wearing of the uniform, they provide personal protection against a wide variety of medically important insect/arthropod pests. Availability and current pricing can be obtained by calling the DGSC at DSN 695-4865: a. Insect/Arthropod Repellent Lotion (cream, 2 fluid ounces). The lotion, NSN 6840-01-284-3982, is not labeled for ticks, but will repel chigger mites and many biting flies. b. Permethrin Arthropod Repellent, Insect Repellent, Clothing Application (aerosol, 6 ounces) NSN 6840-01-278-1336. Seventy-five percent of the can is used to apply to the field uniform and the remainder is used to treat mosquito netting. The product provides protection from ticks and mosquitoes for a maximum of five weeks or five launderings. Use more repellent frequently if "buddy checks" reveal attached ticks. c. Insect Repellent Fabric Treatment (liquid, 5.1 fluid ounces) NSN 6840-01-334-2666. The contents are added to 2 gallons of water and applied with the 2-gallon sprayer from a field sanitation kit at a pressure of 50 pounds per square inch to field uniforms, mosquito netting, and tent fabric to provide protection from ticks, biting flies, and other insects. Since most sprayers are not equipped with the required pressure gauge (NSN 3740- 01-332-8746), it will be necessary to obtain a pressure gauge and filter (NSN 4330-01-332-1639), in order to complete the retrofitting. Proper application can provide protection for the normal life of the uniform, six launderings of mosquito netting, and 6-9 months of treatment for tent fabric, depending on the climate. 2. Detailed directions for the use of these and other repellents can be found in the U.S. Army Environmental Hygiene Agency Technical Guide (TG) 174, Personal Protective Techniques Against Insects and Other Arthropods of Military Significance. 3. The U.S. Army Medical Department Tick-Borne Disease Card (7189) is available from USAEHA-North, ESD.