LYME DISEASE RISK ASSESSMENT, FORT LEONARD WOOD, MISSOURI, 5 MAY - 22 JULY 1994 DEPARTMENT OF THE ARMY U.S. 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: MCHB-AW-P (40-5f) 8 August 1994 LYME DISEASE RISK ASSESSMENT NO. 16-66-A3GY-93 FORT LEONARD WOOD, MISSOURI 5 MAY - 22 JULY 1994 1. REFERENCES. a. Memorandum, this Activity, HSHB-AW-P, 22 January 1992, subject: Lyme Disease Risk Assessment No. 16-66-AF35-92, Fort Leonard Wood, Missouri, 16- 17 November 1992. b. Memorandum, this Activity, HSHB-AW-P, 15 April 1994, subject: Tick Collections No. 16-66-A36V-94, Fort Leonard Wood, Missouri, 20 November 1993. c. Dr. Dorothy Feir, Dr. Robert Hall, and Mr. Michael Fobbs, personal communication, 3-4 May 1994. d. Oliver J. et al, Unusual Tick Isolates of Borrelia burgdorferi from Southeast Missouri Associated Geographically and Temporally with Human Lyme Disease, Bologna, Italy, June 19-22, 1994. 2. AUTHORITY. AEHA Form 250, Fort Leonard Wood, MO, 19 April 1994. 3. PURPOSE. To collect ticks for analysis by Polymerase Chain Reaction (PCR) to determine the presence or absence of Borrelia burgdorferi. To send a representative sample of these ticks to the Centers of Disease Control and Prevention (CDC) for additional tests. 4. GENERAL. a. This Activity's Entomological Sciences Division has been conducting Lyme disease surveillance on military installations in 21 western states in support of the U.S. Army Environmental Hygiene Agency's Department of Defense Lyme Disease Program. Ticks were collected at Fort Leonard Wood from drags, walks, and dry ice traps at three locations in late spring 1994. b. CPT Michael Quintana and Mr. William Irwin, the project officers, collected ticks at Fort Leonard Wood on 5 May 1994. Subsequent tick collections were made by SGT Kerry McKinley, Preventive Medicine Service (PVNTMED Svc), Fort Leonard Wood MEDDAC; these ticks were snet to this Activity on 7 June 1994. 5. BACKGROUND. a. In January 1992, 112 ticks of the species Ixodes scapularis collected from deer on Fort Leonard Wood were analyzed in our laboratory with fluorescent antibody (FA) stains for B. burgdorferi. Forty of these ticks were positive (Reference 1a). In November 1993, 5 of 56 I. scapularis collected from deer on Fort Leonard Wood produced DNA fragments when analyzed with PCR. These amplified fragments were sequenced with the resulting nucleotides almost in total alignment with a reference strain of B. burgdorferi from the northeastern United States. However, we have not been able to culture this spirochete from either ticks or ear biopsies (Reference 1b). b. Dr. Dorothy Feir of the University of Saint Louis and Dr. Robert Hall of the University of Missouri have found what appears to be the same spirochete in two other species of ticks collected in Missouri. Approximately 2 percent of Dermacentor variabilis and Amblyomma americanum analyzed for Lyme disease at their laboratories were positive using FA staining. Dr. Feir analyzed some of these ticks with PCR and sequenced the resulting fragments. Her sequences were almost identical to the same reference strain of B. burgdorferi used in our analysis. Attempt to culture spirochetes from these ticks also failed (Reference 1c.). c. The inability to culture spirochetes from these ticks and rodent ear biopsies suggests that the spirochete detected by PCR and FA from Missouri ticks is different from other B. burgdorferi isolates. To date, there is no evidence that these spirochetes cause human infection, but the possibility exists. According to Mr. Michael Fobbs, Missouri Department of Public Health, some people in Missouri have displayed symptoms which are similar to those exhibited by Lyme disease patients in other parts of the country (Reference 1c.). d. Dr. James Oliver at Georgia Southern University has identified a potential enzootic cycle of Lyme disease involving Ixodes dentatus collected from rabbits in Southeast Missouri. He has been able to grow spirochetes from this tick in culture and has described the bacteria as an isolate of B. burgdorferi. However, I. dentatus does not normally bite humans and is not believed to be transmitting this spirochete to man (Reference 1d.). 6. FINDINGS AND DISCUSSION. a. Three species of ticks were collected during two days of sampling and included: One I. scapularis, 28 D. variabilis, and 272 A. americanum. b. Personnel from the United States Army Environmental Hygiene Activity-West (USAEHA-W) analyzed the single I. scapularis, all 28 of the D. variabilis, and 186 A. americanum for the spirochete B. burgdorferi using PCR. Seventy-nine A. americanum were sent to the CDC for analysis. (1) Ixodes scapularis. The single I. scapularis was negative. (2) Dermacentor variabilis. Twenty-eight D. variabilis were separated into 8 pools of 2 to 10 ticks each and analyzed using PCR. Two pools were positive. (3) Amblyomma americanum. One hundred and eighty-six A. americanum were separated into 21 pools of 1 to 25 ticks and analyzed using PCR. Two pools were positive. (4) The results on the A. americanum sent to the CDC in Fort Collins, Colorado are still pending. Attempts are being made at the CDC laboratory to culture spirochetes from these ticks in various media. c. Ixodes scapularis is the major vector of Lyme disease in the United States. However, this tick does not readily bite humans in Missouri and may not play an important role in transmitting diseases to humans in the state. Our findings do suggest that I. scapularis may be vectoring a spirochete to wild mammals that is genetically similar to an isolate of B. burgdorferi from the northeastern United States. It is believed that this same spirochete is also found in both D. variabilis and A. americanum. d. D. variabilis and A. americanum are thought to be poor vectors of Lyme disease. However, both these ticks can be found in large numbers in Missouri, and readily bite humans. These ticks should therefore be considered potential vectors of the spirochete that was detected at Fort Leonard Wood during this study. e. A copy of our computerized tick log which shows our laboratory results, the dates these ticks were collected on your installation, the identification of the ticks, and the sites where the ticks were collected can be found in Appendix B. The tick log will be maintained by our Activity, should you need to reference this information concerning your installation in the future. Additional specimens received will be annotated in the Fort Leonard Wood section of the log. A complete log of all ticks identified from Fort Leonard Wood by this Activity from 1991-1994 has been sent to the MEDDAC Environmental Science Officer at his request. 7. CONCLUSIONS. The vector of Lyme disease in the United States, I. scapularis, has been found on Fort Leonard Wood. A genetically similar spirochete to B. burgdorferi have also been found on the installation. Two other tick species, A. americanum and D. variabilis, may not be an important vector of Lyme disease in other parts of the United States, but evidence exists that suggest these ticks may be involved in transmitting spirochetes to humans in Missouri that may be pathogenic. Personnel training or recreating at Fort Leonard Wood should take every precaution to avoid tick bites. All personnel at Fort Leonard Wood should be informed regarding the tick problem that exists on post. Appendices C and D show personal protective measures that are useful in preventing tick bites. If tick bites occur, medical attention should be sought. [signature] WILLIAM E. IRWIN Lyme Disease Investigator APPROVED: [signature] MICHAEL QUINTANA CPT, MS Chief, Entomological Sciences Division APPENDIX A TECHNICAL ASSISTANCE Technical advice and/or consultation on pest management problems, to include on-site assistance, may be obtained by telephone from our Activity, DSN 943-8090. Please inform your Major Command Consultant if you desire to request on-site assistance from our Activity. Other 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 occupational and environmental health related 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 B Fort Leonard Wood TICK LOG 1994 [Data omitted - data summarized in above report] APPENDIX C 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. Notification 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 that are available from this Activity. 2. Submit any collected live tick specimens (both field-collected or ticks that have been removed from individuals) for identification and immunofluorescent staining or darkfield microscopy testing to the U.S. Army Environmental Hygiene Activity-West, Entomological Sciences Division, Fitzsimons Army Medical Center, Aurora, CO 80045-5001. 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 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)] 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 the spring when Amblyomma americanum nymphs (the life stage responsibile for most human Lyme disease infections) and adults 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. Army Environmental Hygiene Agency, ATTN: HSHB-MR-E, Aberdeen Proving Ground, MD 21010-5422, or by telephone at 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. Surveillance is necessary due to the patchy distribution of A. americanum. 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., November - 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 APPENDIX D REPELLENTS 1. Several arthropod repellents 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 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 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 U.S. Army Environmental Hygiene Activity-West, Entomological Sciences Division.