LYME DISEASE RISK ASSESSMENT, CAMP EDWARDS MASSACHUSETTS, NOV-DEC 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 (40-5) 07 OCT 1993 LYME DISEASE RISK ASSESSMENT NO. 16-61-AW41-93 CAMP EDWARDS BOURNE, MASSACHUSETTS 28 NOVEMBER - 1 DECEMBER 1992 1. REFERENCES. a. Lyme Disease Surveillance Summary, Vol. 4, No. 3, Centers for Disease Control and Prevention, June 1993. b. Armed Forces Pest Management Board Technical Information Memorandum No. 26, Lyme Disease: Vector Surveillance and Control, March 1990. c. Memorandum, USAEHA-North, HSHB-AN-P, 4 August 1992, Subject: Lyme Disease Risk Assessment No. 16-61-AL14-92, Camp Edwards, Bourne, Massachusetts. 2. AUTHORITY. AEHA Form 250-R, NGB, 2 September 1992. 3. PURPOSE. To assess the risk of Lyme disease to Camp Edwards personnel by collecting the tick vector, Ixodes scapularis (formerly named Ixodes dammini), and assaying collected ticks for the Lyme disease etiologic agent, Borrelia burgdorferi. To compare infection rates in ticks collected from white-tailed deer and those collected via environmental sampling, in order to evaluate deer-derived tick infection rates in ascribing risk. 4. GENERAL. a. Risk Definition. The term "risk", as used in this report, is a nonstatistical evaluation of qualitative and quantitative information available on Lyme disease locally. To the extent available, information evaluated includes the following elements: (1) History of Lyme disease in the area (2) The presence of the tick vector (I. scapularis) and a 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 (4) The presence of antibodies to B. burgdorferi in the mammalian host population Once gathered, this information was used to ascribe risk in the following manner: Low - Some risk elements identified in nearby areas, not locally Moderate - Some risk elements identified from the installation, or human Lyme cases reported locally High - All risk elements present on the installation b. Personnel Contacted. See Appendix A for a list of personnel contacted. c. Survey Support. The field survey was conducted by Mr. Karl Neidhardt and Mr. Ben Pagac, Entomologists, this Activity. Serum samples were assayed via Indirect Fluorescent Antibody (IFA) tests by personnel of the U.S. Army Regional Veterinary Laboratory, Fort George G. Meade, Maryland for the presence of antibody to the Lyme spirochete. Ticks were identified and assayed via polyclonal and monoclonal Direct Fluorescent Antibody (DFA) and IFA tests, respectively, by personnel of this Activity for the presence of B. burgdorferi. 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 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 documented spread of this disease. b. Epidemiological data for 1992 from the Massachusetts Department of Public Health indicate 25 confirmed human cases of Lyme disease in Barnstable County, the county where Camp Edwards is located, and 223 cases statewide. The Centers for Disease Control and Prevention (CDC) reported a slightly different figure of 212 confirmed cases in 1992. 6. METHODS. a. Deer Examinations. The head, ears, and neck of 36 hunter-shot white-tailed deer (Odocoileus virginianus) were examined during weigh-in and tagging at the Camp Edwards deer check station on 30 November. The deer hair were stroked against the natural lay, to expose the skin. If ticks (or other arthropods) were detected, they were removed, using fine- point (No. 5) jeweler's forceps. Total examination time per carcass was approximately 5 minutes. Collected ticks were placed in labeled, 20 ml humidified vials and kept cool (1.5-4.5 degrees C). Collected specimens were returned to this Activity for identification and testing. b. Environmental Collections. On the day prior to the start of hunting season (29 November), host seeking ticks were collected from woodland bushes and leaf litter by dragging a flannel cloth over the bushes and leaf litter to simulate a passing animal. The white cloth and clothing of personnel dragging the cloth were examined for ticks after every 10 paces, and ticks attached were removed using fine-point (No. 5) jeweler's forceps. Ticks were collected from eight locations across the installation. Each site was dragged for approximately one hour. Collected ticks were placed in labeled, 20 ml humidified vials and kept cool (1.5-4.5 degrees C). Collected specimens were returned to this Activity for identification and testing. c. Tick Testing. Collected ticks were tested via a two-phase fluorescent antibody assay. Ticks were first tested using a polyclonal DFA procedure that tests for the presence of spirochetes belonging to the genus Borrelia. Ticks identified as containing these Borrelia spp. spirochetes were further tested to ascertain if the spirochetes were B. burgdorferi specifically. This B. burgdorferi specific test used a H5332 monoclonal IFA procedure. Tick infection rates for the Lyme disease-causing spirochete were calculated based on test results. d. Blood Samples. Blood pooled in the deer body cavities was collected using clean 4 ml disposable plastic pipettes. Samples were placed in 7 ml labeled tubes and spun to separate sera. The sera were pipetted off and frozen (-9 degrees C) until IFA testing could be performed by personnel of the Regional Veterinary Laboratory, Fort George G. Meade, MD. 7. RESULTS. (See also Appendices B, C and D) a. Eight hundred fifty-three I. scapularis ticks were collected from 33 of 36 deer examined. Eight hundred forty-five of these ticks were tested, and 134 (16%) were found to be positive for Borrelia spp.. Follow-up species-specific antibody tests confirmed that 120 of the 134 Borrelia positive ticks were positive for B. burgdorferi, resulting in a 14% B. burgdorferi infection rate. b. One hundred thirty-six Dermacentor albipictus ticks were collected from 21 of 36 deer examined. One hundred thirty-two of these ticks were tested and none was found to be positive for Borrelia spp.. c. Four (12%) of 33 deer sera tested were positive (greater than 1:128 titer level) for B. burgdorferi antibodies. d. Two hundred fifty-four host seeking I. scapularis were collected in eight environmental samples. Two hundred fifty-three of these ticks were tested, and 141 (56%) were found to be positive for Borrelia spp.. Follow-up species-specific antibody tests confirmed that 139 (99%) of the 141 Borrelia positive ticks were positive for B. burgdorferi, resulting in a 55% B. burgdorferi infection rate. 8. DISCUSSION. a. This survey confirms evidence gathered in 1991 (reference 1.c) that the tick vector and the Lyme disease spirochete are established at Camp Edwards. This survey demonstrated specifically that the Lyme disease spirochete B. burgdorferi was present. New information from this survey indicates that using infection rates in ticks, based on assaying ticks removed from deer, underestimates the infection rate in host seeking ticks and therefore the Lyme disease risk to humans in general. b. The significance of the presence of non-burgdorferi, Borrelia spp. in tested ticks is yet to be determined. Research institutions and the CDC are currently investigating differences in Borrelia species and strains relative to their geographic occurrence, host tick species, and the pathogenic implications. 9. CONCLUSIONS. The abundance of I. scapularis, the 55% infection rate in host seeking I. scapularis, and information from the Massachusetts Department of Public Health on the epidemiology of Lyme disease in Barnstable County and surrounding areas, indicate that the present risk of contracting Lyme disease at Camp Edwards is HIGH. Participants in outdoor training and natural resources activities are all at risk for contracting Lyme disease at Camp Edwards. 10. RECOMMENDATIONS. a. Implement recommendations in accordance with guidelines in Appendix E. b. Emphasize, to all troops, outdoor workers, residents, and visitors the importance of applying risk reduction measures, as detailed in Appendices E and G. c. Conduct biennial follow-up surveillance using methods described in reference 1.b and paragraph 6, above. 11. DIRECT SUPPORT ASSISTANCE. Additional direct support in the areas of pest management, pesticide risk management, water supply management, wastewater management, hazardous waste management, ergonomic evaluations, worksite hazards management, health care hazards management, sanitation and hygiene, and installation industrial hygiene management is available, and may be requested from USAEHA-North at DSN 923-6502/5281/6205, or commercially (301) 677-6502/5281/6205. (signature of Ben B. Pagac, Jr.) for KARL NEIDHARDT Entomologist Entomological Sciences Division APPROVED BY: [signature] GEORGE J. MAGNON MAJ, MS Chief, Entomological Sciences Division APPENDIX A PERSONNEL CONTACTED 1. Ms. Elenora Babij, State Environmental Specialist, Headquarters, Massachusetts Army National Guard. 2. MAJ Arthur Gerard, Range Control Officer, Camp Edwards. 3. Mr. John Jacobson, Environmental Officer, Camp Edwards. 4. Ms. Palma, Division of Communicable Disease Control, Massachusetts Department of Public Health, Massachusetts. 5. Mr. Dick Turner, District Game manager, Southeastern Wildlife District, Division of Fisheries and Wildlife, Massachusetts. APPENDIX B TICK TESTING RESULTS CAMP EDWARDS 29-30 NOVEMBER 1992 Table B-1. Ixodes scapularis collected from 33 of 36 deer. ------------------------------------------------------------------------- Borrelia spp. B. burgdorferi --------------------- ---------------------- #COLLECTED #TEST # + % + #TEST # + % + LARVAE 0 0 0 0 0 0 0 NYMPHS 0 0 0 0 0 0 0 ADULTS 853 845 134 16 134 120 90 === === === === === === === TOTAL 853 845 134 16 134 120 90 ------------------------------------------------------------------------- Table B-2. Dermacentor albipictus collected from 21 of 36 deer. ------------------------------------------------------------------------- Borrelia spp. B. burgdorferi --------------------- ---------------------- #COLLECTED #TEST # + % + #TEST # + % + LARVAE 0 0 0 0 0 0 0 NYMPHS 31 30 0 0 0 0 0 ADULTS 105 102 0 0 0 0 0 === === === === === === === TOTAL 136 132 0 0 0 0 0 ------------------------------------------------------------------------- Table B-3. Host seeking Ixodes scapularis collected from 8 drag sites. ------------------------------------------------------------------------- Borrelia spp. B. burgdorferi --------------------- ---------------------- #COLLECTED #TEST # + % + #TEST # + % + LARVAE 0 0 0 0 0 0 0 NYMPHS 0 0 0 0 0 0 0 ADULTS 254 253 141 56 141 139 99 === === === === === === === TOTAL 254 253 141 56 141 139 99 ------------------------------------------------------------------------- APPENDIX C INFECTION RATE COMPARISON CAMP EDWARDS 29-30 NOVEMBER 1992 Table. Comparison of Borrelia burgdorferi infection rates in host seeking and attached Ixodes scapularis. ------------------------------------------------------------------------- B. spp. B. burgdorferi --------------------- ---------------------- ADULT TICKS # TESTED # + % + # TESTED # + % + ------------------------------------------------------------------------- Host Seeking 253 141 56 141 139 55 Attached (deer) 845 134 16 134 120 14 ------------------------------------------------------------------------- Notes: The infection rates for host seeking and attached ticks are significantly different (Chi-Square test P greater than .001). APPENDIX D DEER SEROLOGY RESULTS CAMP EDWARDS 30 NOVEMBER 1992 Table. SERUM SAMPLES FROM 33 DEER TESTED FOR Borrelia burgdorferi ANTIBODY ------------------------------------------------------------------------- Borrelia burgdorferi Antibody ----------------------------- #COLLECTED #TEST # + % + TOTAL 33 33 4 12 ------------------------------------------------------------------------- APPENDIX E 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 (GTA 8-5-56), 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 F 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 G 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.