LYME DISEASE RISK ASSESSMENT, CAMP RIPLEY, MINNESOTA, OCT 1992-FEB 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) 16 February 1993 LYME DISEASE RISK ASSESSMENT NO. 16-66-A1CJ-93 CAMP RIPLEY, MINNESOTA 16 OCTOBER 1992-8 FEBRUARY 1993 1. REFERENCES. a. Memorandum, this Activity, HSHB-AW-P, 21 January 1992, subject: Lyme Disease Risk Assessment, Project No. 16-66-AC56-92. b. Memorandum, this Activity, HSHB-AW-P, 25 August 1992, subject: Lyme Disease Risk Assessment No. 16-66-AF29-92, Camp Ripley, Minnesota, 21-27 June 1992. 2. AUTHORITY. AEHA Form 250, Camp Ripley, 14 October 1992. 3. PURPOSE. To identify ticks and determine if the species present are vectors of Lyme disease, and to analyze the ticks to determine the presence or absence of Borrelia burgdorferi, the causative agent for Lyme disease. See Appendix A for other assistance that can be obtained from the U.S. Army Environmental Hygiene Activity-West (USAEHA-W). 4. FINDINGS AND DISCUSSION. a. This Activity's Entomological Sciences Division has been conducting Lyme disease surveillance on military installations in 21 western states in support of our Agency's DOD Lyme Disease Program. Personnel from Camp Ripley send adult and nymphal ticks, collected on the installation, to the USAEHA-W Entomological Sciences Division Laboratory. These ticks were collected between 16 October and 1 November 1992 from deer on two separate deer hunts. The deer population is known to support a population of Ixodes dammini, the vector species for Lyme disease (see Lyme Disease Risk Assessment 16-66-AC56-92). This assessment, performed by this Activity in the fall of 1991, confirmed that the vector of Lyme disease was present on Camp Ripley. Because of the findings in this Lyme Disease Risk Assessment, the Minnesota National Guard requested a more through risk assessment be performed. A rodent survey was done in June 1992, and the spirochete that causes Lyme disease, Borrelia burgdorferi, was found in both the rodents and ticks collected at Camp Ripley. Therefore, the risk of acquiring Lyme disease was determined to be high (see Lyme Disease Risk Assessment 16-66-AF29-92). The current assessment confirms the June 1992 results. b. Of the six deer shot during the first deer hunt all were positive for Ixodes dammini. A total of 58 of the 90 deer shot during the second hunt was positive for I. dammini. When this data is compared to the previous years deer hunt data, where only 7 deer out of 70 were positive for I. dammini, it is obvious that the infestation rate of the deer with Ixodes ticks has increased. The number of I. dammini collected from deer has also increased. In the fall of 1993, only 14 I. dammini were collected from 70 deer. In the fall of 1992, 383 I. dammini were collected from 96 deer. This data provides evidence that the population of Ixodes dammini has increased from 1991 to 1992. c. In addition to the I. dammini, there were 52 winter ticks, Dermacentor albipictus, collected from deer during the two hunts. These ticks do not usually bite man and are not considered important in the epidemiology of Lyme disease. d. Our laboratory personnel processed the specimens sent to USAEHA-W and tested them for the presence of the spirochete, B. burgdorferi. All I. dammini ticks were either analyzed, saved as part of our reference collection, or frozen for future analysis. The following results were obtained. (1) There were of [sic] 175 I. dammini examined by fluorescent antibody staining. Thirteen of these ticks were positive for spirochetes. (2) Nineteen cultures of tick pools with three to seven ticks in each pool were placed up in BSK II media. Six of these cultures were positive for spirochete growth. The spirochetes in one of these cultures was confirmed by Polymerase Chain Reaction (PCR) to be Borrelia burgdorferi, the causative agent of Lyme disease. e. A copy of our computerized tick log is enclosed which shows the dates ticks were collected on your installation, the identification of the ticks, the sites where the ticks were collected, and our laboratory results (Appendix B). The tick log will be maintained by our Activity, should you need to reference this information concerning this installation in the future. Additional specimens received will be annotated in the Camp Ripley section of the log. f. It is not the intention of this report to determine the infection rate of ticks at Camp Ripley. However, the infection rate in the sample received from Camp Ripley was less than 8 percent. A previous study by USAEHA-W in June 1992 has shown infection rates as high as 36 percent in ticks collected from rodents from certain areas on Camp Ripley. In order to determine infection rates in ticks and consequently a more accurate risk assessment more ticks are needed, especially nymphal Ixodes dammini. The infection rate of questing nymphal I. dammini is unknown, and it is this stage of develpoment that is most responsible for the transmission of Lyme disease to man. Until more nymphal ticks are collected and tested throughout the installation, an accurate assessment of the infection rate of Ixodes dammini can not be made. g. Camp Ripley is an endemic area of Lyme disease, and the risk of acquiring the disease is high. Implementation of personal protective measures is warranted for all outdoor training or recreational activities. The risk of contracting Lyme disease can be reduced by implementing the guidelines in Appendices C and D. 5. CONCLUSIONS. Ixodes dammini, the vector species for Lyme disease, was present in the ticks received from Camp Ripley. Borrelia burgdorferi, the causative agent for Lyme disease, was found in the ticks examined. The use of personal protective measures against acquiring tick bites on Camp Ripley is encouraged. [signature] William E. Irwin Lyme Disease Investigator APPROVED: [signature] THOMAS P. GARGAN II MAJ, 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 943-4838 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 CAMP RIPLEY TICK LOG 1992 [Data omitted - summarized in above report] APPENDIX C 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 laundering 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 USAEHA-W, ESD. APPENDIX D 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 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 presentations on Lyme disease that are 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 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 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, 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 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 (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