LYME DISEASE RISK ASSESSMENT, FORT BRAGG, NORTH CAROLINA, 31 OCT 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) 06 AUG 1993 LYME DISEASE RISK ASSESSMENT NO. 16-61-AW44-93 FORT BRAGG, NORTH CAROLINA 31 OCTOBER 1992 1. REFERENCES. See Appendix A. 2. AUTHORITY. AEHA Form 250-R, HSC, 7 July 1992. 3. PURPOSE. To assess the risk of Lyme disease to Fort Bragg personnel by examining deer for the tick vector, Ixodes scapularis (formerly named 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 available to determine the potential to acquire Lyme disease. 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 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 areas 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 with CPT Jeffery Ryan, Commander, 714th Medical Detachment, 44th Medical Brigade, Fort Bragg, North Carolina. Ms. Susan Sinclair, Lyme disease Project, Communicable Disease Control Section, Division of Epidemiology, North Carolina Department of Environment, Health and Natural Resources (DEHNR), was contacted for epidemiological data concerning human Lyme disease cases in Cumberland County and North Carolina. LTC Kelley Mckee, Chief, Preventive Medicine Activity, Womack Army Medical Center (WAMC), Fort Bragg, North Carolina, was contacted for epidemiological data concerning human Lyme disease cases at Fort Bragg. c. Survey Support. Personnel from the 714th Medical Detachment collected samples. Ticks were identified and assayed via Direct Fluorescent Antibody (DFA) tests by personnel of this Activity. Serum samples from deer were not collected during this survey. 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 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 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. Epidemiological data for 1992 from the North Carolina DEHNR reveal 67 cases of human Lyme disease in North Carolina that met the Centers for Disease Control and Prevention (CDC) guidelines, including confirmation by isolation of B. burgdorferi. No human Lyme disease cases were reported by the DEHNR in 1992 from Cumberland County, where Fort Bragg is located. LTC Mckee, WAMC, reported no confirmed cases of human Lyme disease acquired at Fort Bragg. Most of the human Lyme disease cases in North Carolina were reported from north central Wake County (11 cases) and from coastal Onslow County (10 cases). 6. METHODS. a. Tick collection. Deer, the preferred host for the adult stage of the Lyme disease tick vector, were examined at the check station at Fort Bragg. Deer examined were local deer from or near Fort Bragg. The heads, ears, and necks of 20 hunter-shot white-tailed deer, (Odocoileus virginianus) were examined for the presence of ticks immediately before the weighing and tagging process. The hair on deer were stroked against the natural lay, using the hand edge. If ticks (or other arthropods) were detected, they were removed using fine-point (No. 5) jeweler's forceps and the specimens were returned to this Activity for identification and testing. Total examination time per carcass was approximately 5-10 minutes. b. Tick Testing. Collected ticks were tested via a two-phase DFA assay. Ticks were first tested using a purified antibody (Kirkegaard & Perry Laboratories, Inc., Gaithersburg, Maryland), for the presence of spirochetes of the genus Borrelia. One of the Borrelia, B. burgdorferi, is the causative agent for Lyme disease. Those ticks found to be positive in the Borrelia spp. test, were further tested using a B. burgdorferi, species-specific purified antibody (Kirkegaard & Perry Laboratories, Inc.). Infection rates were determined specifically for the Lyme disease-causing spirochetes. Tick assays were performed by personnel of this Activity. 7. RESULTS. (See also Appendices B and C) a. Fifty-six I. scapularis ticks were collected from eight (40%) of the 20 deer examined. One of the 56 ticks tested positive for Borrelia spp., but was found to be negative for B. burgdorferi. b. Thirteen Amblyomma americanum ticks were collected from 6 (30%) of the 20 deer examined. Two of the 13 ticks tested positive for Borrelia spp. were positive. No ticks tested positive for B. burgdorferi. c. Eight Dermacentor albipictus ticks were collected form four (20%) of the 20 deer examined. None of the eight ticks tested positive for spirochetes. 8. DISCUSSION. a. The significance of the presence of non-burgdorferi, Borrelia spp. in tested ticks is yet to be determined. Research institutions and the Centers for Disease Control and Prevention (CDC) are currently investigating differences in Borrelia species and strains relative to their geographic occurrence, host tick species, and the pathogenic implications. It cannot be assumed that spirochetes detected and identified as B. burgdorferi, using currently available methods, are the only Borrelia that may cause Lyme disease type symptoms. b. This survey provides continued evidence of the presence of the Lyme disease vector and the associated threat to personnel at Fort Bragg. Data presented in Lyme Disease Profile No. 16-61-0504-91 (reference 7) indicated spirochete presence among Ixodes spp. ticks collected on deer at Fort Bragg. Deer serology too was indicative of exposure to the causative agent of Lyme disease. Evidence of Borrelia in additional species of ticks at Fort Bragg, was demonstrated in Lyme Disease Profile No. 16-61-0507-91 (reference 8). In that survey, ticks were collected from mice and dogs. Results of this survey, using a more specific test for B. burgdorferi, indicate that these previously detected spirochetes were probably not B. burgdorferi. Although the sample of deer examined during this most recent survey did not indicate the presence of the Lyme disease-causing spirochete, the potential at-risk human population, availability of animal hosts, and history of human Lyme disease in North Carolina, warrant continued surveillance and caution. Additional study is warranted to determine if the spirochete detected is pathogenic to humans, and to sample for the presence of B. burgdorferi. 9. CONCLUSIONS. The presence of specimens of I. scapularis on examined deer, and information from the DEHNR on the epidemiology of Lyme disease in North Carolina, indicate that the present risk of contracting human Lyme disease at Fort Bragg, is Moderate. 10. RECOMMENDATIONS. a. Implement risk reduction measures in Appendix D. b. Make military, civilians, and dependents aware of information on repellents contained in Appendices E and F. c. Assist this Activity in conducting biennial follow-up surveillance using the methods described in reference 2 and paragraph 6, above. 11. ADDITIONAL 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, 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] GEORGE J. MAGNON MAJ, MS Chief, Entomological Sciences Division APPENDIX A REFERENCES CITED/CONSULTED 1. AR 40-5, Preventive Medicine, 15 October 1990. 2. Armed Forces Pest Management Board Technical Information Memorandum No. 26, March 1990, Lyme Disease: Vector Surveillance and Control. 3. Lyme Disease Surveillance Summary, Volume 3, No. 3, September, 1992, Centers for Disease Control and Prevention. 4. Morbidity and Mortality Weekly Report, Volume 42, No. 18, May 14, 1993, Centers for Disease Control and Prevention. 5. Oliver, J.H. Jr., et al. 1993. Conspecificity of Ticks Ixodes scapularis and Ixodes dammini (Acari: Ixodidae). J. Med Ent. 30(1):54-63. 6. Benenson, A.S. (ed.). 1990. Control of Communicable Diseases in Man. American Public Health Association. 532 pp. 7. Memorandum, USAEHA-North, 7 May 1991, subject: Lyme Disease Profile No. 16-61-0504-91, Fort Bragg, North Carolona, 20 October, 3 November, and 28 November 1991. 8. Memorandum, USAEHA-North, 22 October 1991, subject: Lyme Disease Profile No. 16-61-0507-91, Fort Bragg, North Carolona, 1-3 May, 25 June, and 5 August 1991. APPENDIX B DATA SUMMARY SHEET DOD LYME DISEASE SURVEY U.S. ARMY ENVIRONMENTAL HYGIENE ACTIVITY-NORTH FORT BRAGG, NORTH CAROLINA 31 OCTOBER 1992 # DEER EXAMINED 20 # DEER WITH Ixodes scapularis [1] 8 # DEER WITH TICKS 18 # HUMAN LYME DISEASE CASES, 1992 - FORT BRAGG 0 # HUMAN LYME DISEASE CASES, 1992 - CUMBERLAND CO. 0 # HUMAN LYME DISEASE CASES, 1992 - NORTH CAROLINA 67 [1] Ixodes dammini and Ixodes scapularis have been synonymized by Oliver et al. (1993). APPENDIX C RESULTS FROM 20 DEER EXAMINED AT FORT BRAGG, NORTH CAROLINA 31 OCTOBER 1992 Table C-1. Ixodes scapularis collected from 8 of 20 deer and tested via DFA for Borrelia species and Borrelia burgdorferi =========================================================================== Borrelia spp. B. burgdorferi -------------------- --------------------- #COLLECTED #TESTED # + % + # TESTED # + % + LARVAE 0 0 0 0 0 0 0 NYMPHS 0 0 0 0 0 0 0 ADULTS 56 56 1 2 1 0 0 ===== ===== ===== ===== ===== ===== ===== TOTAL 56 56 1 2 1 0 0 =========================================================================== Table C-2. Amblyomma americanum collected from 6 of 20 deer and tested via DFA for Borrelia species and Borrelia burgdorferi =========================================================================== Borrelia spp. B. burgdorferi -------------------- --------------------- #COLLECTED #TESTED # + % + # TESTED # + % + LARVAE 3 3 2 67 2 0 0 NYMPHS 6 6 0 0 0 0 0 ADULTS 4 4 0 0 0 0 0 ===== ===== ===== ===== ===== ===== ===== TOTAL 13 13 2 15 2 0 0 =========================================================================== APPENDIX C - CONTINUED RESULTS FROM 20 DEER EXAMINED AT FORT BRAGG, NORTH CAROLINA 31 OCTOBER 1992 Table C-3. Dermacentor albipictus collected from 4 of 20 deer and tested via DFA for Borrelia species and Borrelia burgdorferi =========================================================================== Borrelia spp. B. burgdorferi -------------------- --------------------- #COLLECTED #TESTED # + % + # TESTED # + % + LARVAE 0 0 0 0 0 0 0 NYMPHS 7 7 0 0 0 0 0 ADULTS 1 1 0 0 0 0 0 ===== ===== ===== ===== ===== ===== ===== TOTAL 8 8 0 0 0 0 0 =========================================================================== Table C-4. TOTAL TICKS collected from 18 of 20 deer and tested via DFA for Borrelia species and Borrelia burgdorferi =========================================================================== Borrelia spp. B. burgdorferi -------------------- --------------------- #COLLECTED #TESTED # + % + # TESTED # + % + TOTAL 77 77 3 4 3 0 0 =========================================================================== APPENDIX D 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-N, 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 E 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 U.S. Army Medical Department Tick-Borne Disease Card (7189) 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.