LYME DISEASE RISK ASSESSMENT, FORT DRUM, NEW YORK, 28 JUNE - 2 JULY 1993 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) 28 OCT 1993 LYME DISEASE RISK ASSESSMENT NO. 16-61-A11L-93 FORT DRUM, NEW YORK 28 JUNE - 2 JULY 1993 1. REFERENCES. See Appendix A. 2. AUTHORITY. AEHA Form 250-R, HSC, 2 March 1993. 3. PURPOSE. To assess the risk of Lyme disease to Fort Drum personnel by examining deer for the tick vector, Ixodes scapularis (formerly Ixodes dammini) and to assay ticks for the Lyme disease etiologic agent, Borrelia burgdorferi, in accordance with AR 40-5, paragraph 10-7.f. 4. GENERAL. a. Risk Definition. The term "risk," as used in this report, is a non-statistical evaluation of qualitative and quantitative information on Lyme disease locally. To the extent available, information evaluated includes the following elements: history of Lyme disease in the area, the presence or absence of the tick vector (I. scapularis) and the mammalian host population needed to sustain a viable population of the vector, the presence of the Lyme disease-causing spirochete (B. burgdorferi) in the tick population, and the presence of B. burgdorferi or antibodies to B. burgdorferi in the mammalian host population. Criteria for risk categorization follow: Low - Some elements of the Lyme disease cycle identified in nearby area, but not on the installation Moderate - Some elements of Lyme disease cycle identified from the installation or human cases of Lyme disease reported from the local area High - All elements of the Lyme disease cycle present on the installation b. Personnel Contacted. The purpose and methodology of this assessment were discussed in briefings with the following personnel at Fort Drum: CPT Theresa Cutler, Environmental Science Officer, Preventive Medicine Service (PVNTMED Svc), Fort Drum Medical Department Activity (MEDDAC), and Mr. Jim Hessil, Biologist, Directorate of Engineering and Housing. Preliminary results of this survey were discussed with CPT Cutler and Mr. Hessil at the conclusion of the field work. Dr. Dennis White, Entomologist, New York State Department of Health, and Dr. Durland Fish, Director, Medical Entomology Laboratory, New York Medical College, were also consulted regarding the results of this survey. c. Survey Conduct. Mr. Benedict Pagac, Entomologist, this Activity, conducted this assessment. Assistance was provided in the field by CPT Cutler, SGT Aaron Mueller, and SGT Russell Wolfe, all of the PVNTMED Svc, Fort Drum MEDDAC. This survey was planned to coincide with the expected I. scapularis nymphal population peak. This survey was also designed as a follow-up to an identical survey conducted in mid-June of 1991 by this Activity. Ticks were identified and assayed via Direct Fluorescent Antibody (DFA) tests by personnel of this Activity. Animal tissue samples were assayed for B. burgdorferi spirochetes by personnel of the U.S. Army Environmental Hygiene Activity-West, Fitzsimons Army Medical Center, Aurora, Colorado. d. Technical Assistance. Technical assistance or further informal advice may be obtained by contacting Chief, Entomological Sciences Division, this Activity, commercial (301) 677-5281/6502 or DSN 923- 5281/6502. 5. BACKGROUND. a. Lyme disease is a multi-symptomatic infectious disease caused by the bacterial 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 Army Surgeon General reported 379 cases of Lyme disease contracted on Department of Defense (DOD) installations from 1987 through 1991. During 1991, there were 81 cases of Lyme disease treated in military hospitals, of which 31 of the cases involved either dependents or retired members. The need to protect soldiers and other personnel working on DOD installations has increased with the spread of this disease. b. New York health authorities reported a provisional statewide total of 3,370 confirmed human cases of Lyme disease during 1992, a decrease of 574 cases from 1991. 6. METHODS. a. Animal Trapping. Animals were trapped using Sherman live capture traps baited with peanut butter and rolled oats. At least 45 traps were set at each of nine different sites within areas having appropriate habitat. Baited traps were put out in the late afternoon and collected early the next morning. Captured animals were anesthetized, examined microscopically (60X-300X) for parasites, ear biopsies were taken, and the animals were then returned alive to their respective trapping sites. Trapping took place in three major vicinities: Fargo, Natural Bride, and Indian Lake. Maps showing specific trapping locations are on file at PVNTMED Svc, Fort Drum and at this Activity. b. Tick Testing. Ticks were assayed via DFA testing to determine number of ticks infected with the Lyme disease spirochete, B. burgdorferi. c. Tissue sampling. Ear biopsies were taken from captured animals. The tissue was washed in decontamination solution, placed in a labeled vial containing a phosphate buffer solution, and frozen until laboratory analysis could take place. Ear biopsies were cultured in the laboratory using BSK II media which is specific for B. burgdorferi spirochetes. 7. RESULTS. a. A total of 67 animals were caught in 406 traps set, yielding a trapping success rate of 17 percent. The breakdown and number of species trapped were as follows: White-footed Mouse (Peroymyscus leucopus) - 56; Woodland Jumping Mouse (Napaeozapus insignis) - 3; Eastern Chipmunk (Tamias striatus) - 2; Voles (Microtus pennsylvanicus, Pitymys pinetorum) - 5; and Shorttail Shrew (Blarina brevicauda) - 1. b. One I. scapularis larva was obtained from a White-footed Mouse trapped near Fargo on the evening of June 29. The I. scapularis larva was negative when tested for the Lyme disease causative agent, B. burgdorferi. Although other ectoparasites (fleas, mites, and lice) were found on some of the captured animals, the majority of the animals were free of any ectoparasites, including other tick species. c. None of the 66 ear biopsies resulted in the culture of B. burgdorferi spirochetes. 8. DISCUSSION. Lyme disease surveillance done in June and November of 1991 revealed one I. scapularis larva present on one of 49 small animals trapped and no ticks on 10 deer shot by hunters (References 5 and 6, respectively). The present survey revealed no evidence of a dramatic change in the epidemiology of this disease at Fort Drum, when compared to the previous results. The significance of finding one larval I. scapularis specimen must be weighed against what is observed in Lyme-endemic regions (Reference 3). For example, ongoing trapping of P. leucopus done in Westchester County, New York, a hyperendemic area, reveals most, if not all mice are infested with I. scapularis in mid-June (Dr. Durland Fish, pers. comm.). The large potential at-risk human population (troops in field training) along with the availability of suitable animal hosts and environmental conditions necessary for the occurrence of Lyme disease all make Fort Drum an area requiring continued vigilance. 9. CONCLUSIONS. The presence of I. scapularis, the recognized tick vector of Lyme disease, was confirmed at Fort Drum. However, based upon the quantitive results of this survey, along with information from previous field work done at Fort Drum and epidemiological information from the State health authorities, the present risk of contracting human Lyme disease at Fort Drum remains LOW. 10. RECOMMENDATIONS. Because the results of this survey reveal that the present risk of contracting Lyme disease at Fort Drum is low, formal recommendations for immediate implementation are not presented. However, due to the documented pattern of spread of this disease agent and vector into regions which had been previously uninvolved, familiarity with risk reduction measures (Appendix B) should be part of contingency planning for reducing the future risk of Lyme disease at Fort Drum. Biennial surveillance of small mammals using the methods described in paragraph 5 above, would be invaluable in providing an early warning to Fort Drum personnel and would allow the timely implementation of preventive measures. 11. ADDITIONAL DIRECT SUPPORT ASSISTANCE. Additional direct support in the fields of pest management, pesticide risk management, water supply management, wastewater management, hazardous waste management, worksite hazards management, health care hazards management, ergonomic evaluation, sanitation and hygiene, and installation industrial hygiene management is available, and may be requested from U.S. Army Environmental Hygiene Activity-North at commercial (301) 677-6502/5281/6205 or DSN 923-6502/5281/6205. [signature of Melissa K. Miller] for BENEDICT B. PAGAC, JR. Entomologist Entomological Sciences Division APPROVED BY: [signature of Karl Neidhardt] for GEORGE J. MAGNON MAJ, MS Chief, Entomological Sciences Division APPENDIX A REFERENCES CITED 1. AR 40-5, Preventive Medicine, 15 October 1990. 2. Armed Forces Pest Management Board Technical Information Memorandum No. 26, Lyme Disease: Vector Surveillance and Control, March 1990. 3. Lyme Disease Surveillance Summary, Vol. 4, No. 3, Centers for Disease Control and Prevention, June 1993. 4. Oliver, J.H., et al. 1993. Conspecificity of Ticks Ixodes scapularis and Ixodes dammini (Acari: Ixodidae). J. Med. Ent. 30(1):54-63. 5. Memorandum, USAEHA-N, HSHB-AN-P, 9 August 1991, subject: Lyme Disease Profile No. 16-61-0508-91, Fort Drum, New York, 17-21 June 1991. 6. Memorandum, USAEHA-N, HSHB-AN-P, 24 February 1992, subject: Lyme Disease Risk Assessment No. 16-61-A375-92, Fort Drum, New York, 1-3 November 1991. 7. Personal communication between Dr. Durland Fish, Director, Medical Entomology Laboratory, New York Medical College, Armonk, New York and Mr. Pagac, USAEHA-North, 15 June 1993. APPENDIX B 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, video "Lyme Disease: A growing threat" (FAUPIN No. 504494DA). A 35mm 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 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. scapularis 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. scapularis. 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 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 directions on the label and in conjunction with the proper wearing of clothing, 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 or commercial (804) 790-4865. Repellents available for use are described below: a. Insect/Arthropod Repellent Lotion (cream, 2 fluid ounces) for application to exposed skin. 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. Apply more 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 55 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 (180 days in the field), 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, June 1991. 3. The Tick-Borne Diseases Card (GTA 8-5-56) is available from the Entomological Sciences Division, USAEHA-North, by calling DSN 923-5281 or commercial (301) 677-5281. APPENDIX F FACT SHEET - MOSQUITO AND TICK REPELLENTS * DEET (N,N-Diethyl-m-tolumide) containing repellents offer good protection against mosquitoes, and are formulated for application to exposed skin. * Permethrin containing repellents offer excellent protection against ticks, and are formulated for application to clothing. * DEET will also offer protection against ticks, keeping them from attaching to treated skin. However, ticks generally do not attach in exposed areas, the only areas DEET may be applied to. * Permethrin, on the other hand, will also offer protection against mosquitoes, but may not be applied to exposed skin where mosquitoes bite. It is useful for treating bed netting. * Combined use of DEET on exposed skin for mosquito repellency and Permethrin on clothing for tick repellency offers maximum protection against both pests. Always read and follow the label before using any compound. * Do not use tick and flea collars. A toxic reaction can result. Humans have sweat glands in their skin that serve as an avenue for chemical absorption. Dogs on the other hand, respire by panting, lacking sweat glands. In addition, pets have a thicker hair barrier than most humans to protect them from direct contact with the collars. * Various lotion products claim protection against mosquitoes. Professional literature both supports and refutes benefits from lotions. However, there is a consensus that mineral oil, a component of many lotions, does substantially reduce mosquito bites on treated skin. * Tests have shown that DEET products containing a high concentration (greater than 50%) of DEET do not offer greater protection than those products containing 30-50% DEET. * The following practices enhance the effectiveness of protection against mosquitoes and ticks when used in conjunction with repellents: - Cover as much exposed skin as possible. Consider loose fitting long- sleeved shirts in summer. - Tuck pants inside socks or boots to keep ticks out. - Wear light-colored clothing to make seeing ticks easier. - Plan ahead and treat clothing with permethrin before your outdoor activity begins. Permethrin binds with fabric and is persistent through several washings. - Store treated clothing in a plastic bag to help preserve repellent effectiveness and identify treated clothing.