LYME DISEASE RISK ASSESSMENT, SAVANNA ARMY DEPOT ACTIVITY, SAVANNA, ILLINOIS, 25-30 JULY 1993 DEPARTMENT OF THE ARMY US Army Environmental Hygiene Activity-West Fitzsimons Army Medical Center Aurora, Colorado 80045-5001 [Seal of Department of Defense, United States of America] REPLY TO ATTENTION OF: HSHB-AW-P (40-5f) 7 September 1993 LYME DISEASE RISK ASSESSMENT NO. 16-66-A12E-93 SAVANNA ARMY DEPOT ACTIVITY SAVANNA, ILLINOIS 25-30 JULY 1993 1. REFERENCE. See Appendix A for a list of references. 2. AUTHORITY. a. AEHA Form 250-R, U.S. Army Health Services Command, 7 July 1992. b. Memorandum, USAEHA, HSHB-ME, 21 September 1992, subject: U.S. Army Environmental Hygiene Agency Scehdule of Field Services, FY 93. 3. PURPOSE. The purpose in performing this risk assessment was to survey for Lyme disease vectors, to determine the prevalence of the infective agent (Borrelia burgdorferi) in rodents and ticks, and to assess the risk of Lyme disease to Savanna Army Depot Activity (SVADA) personnel. See Appendix B for other assistance that can be obtained from the U.S. Army Environmental Hygiene Activity-West (USAEHA-W). 4. GENERAL. a. This Activity's Entomological Sciences Division has been providing educational training to give people a better understanding of Lyme disease. During this survey, a video tape, "Lyme Disease, A Growing Threat", was shown to the Agronomist, the Safety and Occupational Health Manager, the Jo Daviess County Department of Health Sanitarian, and nine SVADA personnel. b. Risk Definition. The term "risk", as used in this report, is a non- statistical determination of qualitative and quantitative information available to evaluate the potential to acquire Lyme disease. To the extent available, information evaluated includes the following elements of the Lyme disease cycle: (1) History of Lyme disease in the area. (2) The presence or absence of the tick vector, the black-legged tick, Ixodes scapularis, 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 in the mammalian reservoir host population. (4) The presence of antibodies to B. burgdorferi in the mammalian host population. The criteria for risk categorization are: Low risk - Some element of the Lyme disease cycle identified in nearby areas but not on the installation. Moderate risk - Some elements of Lyme disease cycle identified from the installation or human cases of Lyme disease identified from the local area. High risk - All elements of the Lyme disease cycle are present on the installation. c. Dr. Lester D. Hale and SFC Hampton Wright, the Survey Officers, discussed the findings and recommendation with SVADA personnel. See Appendix C for a list of personnel contacted. d. The field survey portion of the Lyme Disease Risk Assessment was conducted at SVADA, 26-30 July 1993. The laboratory analyses of ticks and rodent ear biopsies were conducted between 2-17 August 1993. 5. BACKGROUND. a. Savanna Army Depot Activity is located in Jo Daviess and Carrol counties, seven miles north of Savanna, Illinois. The installation is bordered on the west by the Mississippi River and on the east side by Illinois State Highway 84. The installation encompasses approximately 13,000 acres, much of it covered by grass, shrubs, and oak trees. The primary mission of the installation is to store ammunition and associated explosive/pyrotechnic materials. Approximately 5000 Illinois National Guard and Reserve personnel train annually on the installation. b. Illinois reported 27 confirmed cases of Lyme disease for 1992 (Reference 1). No cases of Lyme disease have been reported from Jo Daviess or Carrol counties. No cases of Lyme disease have been reported from SVADA. 6. METHODS. a. Field Survey Procedures. (1) Tick surveys. The tick collecting methods at SVADA included using tick drag cloths, tick flags, and carbon dioxide traps. Ticks were also removed from the ears of trapped rodents. All ticks were kept alive by placing them in water-moistened vials as described in the USAEHA-W, Entomological Sciences Division (ESD) Standing Operating Procedures (SOP) No. 6 and No. 8. For each collection site, all collected ticks were identified, counted, and placed into a marked vial. Ticks collected at different sites were kept segregated and placed into separately marked vials and hand-carried to the USAEHA-W, ESD Laboratory. (a) Tick Drag Techniques. 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. Ticks were then removed from the cloth and placed in a marked vial for that particular dragging operation. (b) Tick Flag Technique. A 3x3-foot piece of white flannel cloth was dragged over the tops of large vegetation, i.e., bushes or was used on steep slopes. Attached ticks were then removed from the cloth and placed in a marked vial for each collection site. Approximately 17,000 linear meters were covered by team members doing the dragging and the flagging. (c) Carbon Dioxide Traps. A 2x2-foot piece of white flannel cloth was placed on the ground with the edges weighted down with stones. An aluminum foil covered pie plate was placed upside down in the middle of the cloth. Approximately 2 pounds of dry ice were wrapped in newspaper and placed on top of the plate. The area around each trap and the cloth were checked for ticks after 2 to 3 hours. (2) Rodent Surveys. Rodents trapped at SVADA were identified using " A Field Guide to the Mammals, North America, north of Mexico" (Reference 4). All rodents were handled in accordance with the guidelines outlined in the National Institutes of Health Publication No. 85-23, Revised 1985, "Guide for the Care and Use of Laboratory Animals" and USAEHA-W, ESD SOP No. 7. (a) Small mammals were captured in live traps (3x3x10 inches) on SVADA. At each site, several trapping locations were selected and one or more trap lines were set in each area. The traps were usually located near ponds and on wooded hillsides with traps located approximately 10 meters apart. From 20 to 40 traps were set at each location for a single night. (b) Each rodent was anesthetized before removing any ticks or taking an ear biopsy. The ear biopsy was placed in a labeled vial containing a phosphate buffer solution and then frozen on dry ice. (3) Specimen Handling Procedures. The ticks collected from rodents and from dragging and flagging vegetation during 27-30 July were hand-carried to the USAEHA-W, ESD Laboratory for identification and analysis. b. Laboratory Assay Procedures. (1) All rodent ear biopsies were surface decontaminated, cut into small pieces, and placed in BSK II, a liquid culture medium specially developed to promote the growth of B. burgdorferi. If any of the trapped rodents were serving as the reservoir hosts for Lyme disease, the spirochetes should grow in the medium. (2) Ticks collected from the rodents and from vegetation were processed by using either darkfield or immunofluorescent microscopy or by using the Polymerase Chain Reaction (PCR) technique. 7. FINDINGS AND DISCUSSION. a. Tick Collections. One American dog tick, Dermacentor variabilis, was collected at the Crim Road Wooded Area (Site 7) from dragging and flagging over the vegetation and no ticks were collected from carbon dioxide traps. The table shows 12 I. scapularis and 17 D. variabilis were removed from the 63 captured rodents. b. Rodent Collections. Two species of rodents were captured at seven sites on SVADA (see table). The deer mouse was the most common rodent captured. TABLE . Number of Ixodes scapularis and Dermacentor variabilis Ticks Removed from Rodents at Savanna Army Depot Activity, Savanna, Illinois. --------------------------------------------------------------------------- RODENTS -------------------------- I. D. SITE No. SPECIES scapularis variabilis --------------------------------------------------------------------------- K Road Pond 8 Peromyscus maniculatus 0 2N,1L (Area 1) (Deer mouse) Grassland K Road 18 Peromyscus maniculatus 0 3N (Area 2) (Deer mouse) 3 Peromyscus leucopus 0 1N (White-footed mouse) Spencer Road 6 Peromyscus maniculatus 0 4N (Area 3) (Deer mouse) Bunker C-501 Wooded Area 13 Peromyscus maniculatus 12L 5N (Area 4) (Deer mouse) Around Bunker F-105 1 Peromyscus maniculatus 0 0 (Area 5) (Deer mouse) 807 Wooded Area 5 Peromyscus maniculatus 0 0 (Area 6) (Deer mouse) Crim Road Wooded Area 9 Peromyscus maniculatus 0 1N (Area 7) (Deer mouse) ----- --------------- TOTAL 63 12L 16N,1L N - Nymph, L - Larva. --------------------------------------------------------------------------- c. Laboratory Results. Detailed information on the laboratory results, are given in Appendix D. (1) Ticks. The I. scapularis and D. variabilis examined by darkfield microscopy, immunofluorescent microscopy were negative for B. burgdorferi. (2) Rodent Ear Biopsies. Sixty-three rodent ear biopsies were cultured in BSK II media for spirochetes. All samples were negative for B. burgdorferi, suggesting that the spirochete had not circulated within the small number of rodents sampled at SVADA. d. Lyme Disease Risk. (1) During the field survey portion of this Lyme disease risk assessment, only one tick was collected by dragging and flagging, and no ticks were collected from carbon dioxide traps. This information reflected comments from installation personnel that few ticks were encountered by people exposed to outdoor field environments on LCAAP. (2) No Lyme disease spirochetes were recovered from either the ticks or from the rodent ear biopsies collected during this assessment. (3) The categories defined in paragraph 4b were used to describe the human health risk from Lyme disease at SVADA. The data collected during this assessment indicated that only one criterion for acquiring Lyme disease were present, the tick vector, I. scapularis. No human cases, however, have been documented as originating on the installation or from Jo Daviess and Carrol counties. While the Risk Definition criteria suggests a Moderate risk, the actual risk to SVADA personnel in the field is probably Low based on the low number of I. scapularis collected on the installation and lack of cases in the local area. (4) Although no human cases of Lyme disease have been diagnosed as originating on SVADA, personal protective measures to guard against tick bites would be prudent. Risk of contracting any tick-borne diseases such as Lyme disease, and Rocky Mountain Spotted Fever (also found in Illinois) can be minimized by the proper wearing of clothing, avoiding areas known to harbor high tick populations, and by using repellents (see Appendix E for repellent products available in the Defense General Supply Center or Self-Service Supply System). General Lyme disease reduction measures can be found in Appendix F. (5) Ticks may be sent to our USAEHA-W, ESD Laboratory; we will identify and analyze submitted specimens for Lyme disease. Continuing surveillance should further define the presence and distribution of ticks and the risk of acquiring Lyme disease on SVADA. Additional collections of ticks should be made from deer during the hunting season in the fall of 1993. Collection kits will be sent to the Safety and Occupational Health Manager at SVADA. 8. CONCLUSIONS. The black-legged tick, I. scapularis, a competent vector of Lyme disease in the state of Illinois, was collected at SVADA. Borrelia burgdorferi, the causative agent for Lyme disease, was not found on the installation. Personnel training, working or residing on SVADA are at Low risk for acquiring Lyme disease; however, implementation of personal protective measures for all military, civilians, and dependents using SVADA for outdoor training or recreation is recommended as a good preventive medicine practice. [signature] LESTER D. HALE Entomologist APPROVED BY: [signature] THOMAS P. GARGAN II MAJ, MS Chief, Entomological Sciences Division APPENDIX A REFERENCES 1. Morbidity and Mortality Weekly Report, Volume 41, No. 51, December 1993, Massachusetts Medical Society. 2. USAEHA-W, ESD SOP No. 6, 24 April 1991, Tick Collection Procedures. 3. USAEHA-W, ESD SOP No. 8, 25 April 1991, Small Mammal Tick and Ear Tissue Collections. 4. Burt, W. H. and R. P. Grossenheider, A Field Guide to the Mammals North America, north of Mexico, Third Edition, Houghton Mifflin Company, Boston, 289pp. 5. National Institutes of Health Publication No. 85-23, Revised 1985, Guide for the Care and Use of Laboratory Animals, U.S. Department of Health and Human Services. 6. USAEHA-W, ESD SOP No. 7, 25 April 1991, Procedures for Trapping and Handling Small Mammals. APPENDIX B TECHNICAL ASSISTANCE Technical advice and/or consultation on pest management problems, to include on-site assistance, may be obtained by telephone from our Activity at DSN 943-8090. Please inform your Major Command Pest Management Consultant if you desire to request on-site assistance from our Activity. Technical services that we can assist you with are as follows: 1. Entomological laboratory support 2. Environmental laboratory support 3. Hazardous waste management 4. Industrial hygiene management 5. Medical systems safety and health 6. Sanitation and hygiene 7. Wastewater management 8. Water supply management 9. Worksite hazards management 10. Cholinesterase testing management For assistance in any of the above listed programs, please call: Environmental Health and Engineering Division - DSN 943-8100 Field sanitation and hygiene; potable, recreational and wastewater quality; hazardous waste management; document/design reviews. Industrial Hygiene Division - DSN 943-8881 Industrial hygiene; hazard communication; protective equipment programs; document/design reviews. Environmental Laboratory Division - DSN 943-3293 Routine and emergency analysis of water, soil, and occupational health- related samples. Cholinesterase Laboratory Division - DSN 943-3318 Testing of red blood cell-cholinesterase (RBC-ChE) specimens and quality assurance consultations and training for RBC-ChE labs. During non-duty hours calls will be recorded by an answering machine and returned the next day. Many additional services are available from our parent organization, the U.S. Army Environmental Hygiene Agency, and are described in AEHA Pamphlet 40-2, Directory of Services (published annually). We will gladly coordinate any additional services you request and that we cannot provide with our parent organization. APPENDIX C PERSONNEL CONTACTED 1. Ms. Bridgette Cottral* Safety and Occupational Health Nurse DSN 585-8838 2. Mr. Gordon Coursen Sanitarian Jo Daviess County Health Commercial (815) 777-0283 3. Ms. JoAnne Deacon* Occupational Health Nurse DSN 585-8216 4. Mr. Bob Speaker* Agronomist DSN 585-8533 5. MAJ Richard R. Thibodeau* Commanding DSN 585-9311 --------- * Individual received an exit briefing. APPENDIX D Savanna Army Depot Activity TICK LOG 1993 [Data omitted - data summarized in above report] APPENDIX E 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) NSN 6840-01-0284-3982. The lotion 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 through six normal launderings. 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 the USAEHA-W, ESD. APPENDIX F 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-7189), 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 (April - September). c. Making available for viewing video and 35mm slide format presentations on Lyme disease; both are available from this Activity. 2. Submit any collected live tick specimens (both field-collected ticks or those that have been removed from individuals) for identification and immunofluorescent staining or darkfield microscopy testing to the Entomological Sciences Division, U.S. Army Environmental Hygiene Activity- West, Fitzsimons Army Medical Center, Aurora, CO 80045-5001. 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, 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 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 spring when Ixodes scapularis nymphs (the life stage responsible for most human Lyme disease infections) are active. 6. 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 telephone DSN 584-3613 or Commercial (410) 671-3613. 7. 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. scapularis. 8. 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., November - February). 9. 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