Lyme Disease Risk Assessment No. 16-07-2709-95, Dover Air Force Base, Delaware, 11 November 1994 DEPARTMENT OF THE ARMY U.S. Army Center for Health Promotion and Preventive Medicine Direct Support Activity-North Fort George G. Meade, Maryland 20755-5225 [Seal of Department of Defense, United States of America] REPLY TO ATTENTION OF: MCHB-AN-ES (40-5f) 29 January 1996 MEMORANDUM FOR Commander, Dover Air Force Base, ATTN: Entomology, 436th CES/CEHO, Dover Air Borce Base, DE 19901-5516 SUBJECT: Lyme Disease Risk Assessment No. 16-07-2709-95, Dover Air Force Base, Delaware, 11 November 1994 1. There is no organized annual white-tailed deer hunt on Dover Air Force Base (DAFB). However, there are significant numbers of deer harvested during annual hunting in the areas immediately surrounding DAFB, and there is a Delaware State game checkpoint (on the Little Creek Wildlife Reservation) within a mile due east of the main runway of DAFB. It was decided that collecting sera and ticks from deer at that site should provide samples which would fairly accurately represent tick/tick-borne pathogen (especially Lyme disease) presence and prevalence in the DAFB area. 2. A total of 495 Lyme disease (LD) vector ticks, Ixodes scapularis Say, were collected from 52 of 58 deer examined at the Little Creek station, 11 November 1994. A total of seven (7) of 43 deer sera tested was positive for the presence of antibodies against the LD etiologic agent, Borrelia burgdorferi. Twenty-three (23) of the 495 ticks (4.6%) tested positive for B. burgdorferi via direct fluorescent antibody (DFA) assays. An additional 25 ticks (5.1%) tested positive for Borrelia spp. via DFA assays. 3. Results of this survey, combined with information from the Delaware Department of Health (DDH), regarding human case reports and LD vector tick collection records from sites relatively near DAFB, indicate that the risk of contracting LD in areas immediately surrounding DAFB is high. All military, civilian, and dependent personnel using DAFB for outdoor training or recreation should use personal protective measures, as addressed in Appendices D, E, and F of this report. The risk of contracting LD on DAFB itself is uncertain because of a total lack of surveillance data needed to make that determination. 4. Copies of the subject report are enclosed. Please call me on DSN- 923-7403/5281 extension 517, or at commercial (301)923-5282/6502 extension 517, if this report does not meet your needs or if you require additional information on this risk assessment or support in the areas of occupational environmental health. FOR THE COMMANDER: [signed by] RICHARD N. JOHNSON MAJ, MS Chief, Entomological Sciences Division ----- DEPARTMENT OF THE ARMY U.S. Army Center for Health Promotion and Preventive Medicine Direct Support Activity-North Fort George G. Meade, Maryland 20755-5225 [Seal of Department of Defense, United States of America] REPLY TO ATTENTION OF: MCHB-AN-ES (40-5f) LYME DISEASE RISK ASSESSMENT NO. 16-07-2709-95 DOVER AIR FORCE BASE, DELAWARE 11 NOVEMBER 1994 1. REFERENCES. See Appendix A. 2. AUTHORITY. AEHA Form 250-R, Dover Air Force Base (DAFB), 1 November 1994. 3. PURPOSE. To asses the risk of Lyme disease (LD) to DAFB personnel by examining deer for known vectors of LD, especially Ixodes scapularis Say, and to assay ticks and deer blood for evidence of the LD etiologic agent, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt and Brenner, in accordance with Department of Defense Directive (DOD Dir.) 4150.7, and Air Force Instruction (AFI) 48-102. 4. GENERAL. a. Risk Definition. The term "risk", as used in this report, is a non-statistical evaluation of qualitative and quantitative information on LD locally. To the extent available, information evaluated included the following elements: (1) History of LD in the area, (2) The presence of the principal tick vector of LD (I. scapularis) and host populations needed to sustain viable populations of this vector, (3) The presence of the LD-causing spirochete (B. burgdorferi) in the local tick population, and (4) The presence of antibodies against B. burgdorferi in the blood serum of local mammal hosts. Once gathered, this information was used to help determine the general relative risk level as follows: Low - Some elements of the LD cycle have been identified nearby, but not on the installation. Moderate - Some elements of the LD cycle have been identified from the installation or human cases of LD have been reported from the local area. High - All elements of the LD cycle have been found (are present) on the installation. b. Personnel Contacted. The purpose and methodology of this survey were discussed with Mr. Popham, Chief, Entomology Division, 436th Civil Engineering Squadron (CES), DAFB, Delaware; Staff Sergeant (SSgt) Farkas and Airman First Class (A1C) Coffman, 436th CES, DAFB; Captain (Capt) Langsten, Military Public Health Office (MPHO) and Technical Sergeant (TSgt) Clark, Preventive Medicine Section, 436th Medical Group, DAFB, DE; Lloyd Alexander, Chief, and Ken Reynolds, Deer Biologist, Division of Fish and Wildlife, Dover, Delaware; Dr. David Wolfe, Epidemiology Division, Department of Health and Human Services, Dover, Delaware; and Dr. Chad McHugh, Armstrong Laboratory, Brooks Air Force Base, Texas. c. Survey Conduct. Blood samples were collected from hunter-killed white-tailed deer, harvested in areas surrounding DAFB, by Dr. Harlan of this Activity (DSA-North) on 11 November 1994. All specimens included herein were from deer checked at the Little Creek deer check station, about one kilometer due east of the northern end of the main north-south runway of DAFB. All deer were examined for ticks. Ticks were later assayed for the presence of B. burgdorferi via direct fluorescent antibody (DFA) techniques at this Activity. Deer sera were assayed for the presence of antibodies against Lyme disease via indirect fluorescent antibody (IFA) tests by personnel of the DoD Veterinary Laboratory at Fort Sam Houston. d. Technical Assistance. Technical assistance or further informal advice may be obtained by contacting the Chief, Entomological Sciences Division, this Activity, commercial (310)677-5281/6502 or DSN 923- 5281/6502. 5. BACKGROUND a. Lyme disease (LD) is a multi-symptomatic infectious disease caused by the spirochete, Borrelia burgdorferi Say [sic], which is transmitted to humans by the bite of an infected tick. This disease is usually called Lyme disease or Lyme arthritis in the United States. Over the past few years, it has become the most prevalent arthropod- borne disease in North America. Its geographic range is expanding and the number of reported cases has continued to rise nearly every year since 1989. b. The number of LD cases reported to the U.S. Centers for Disease Control and Prevention (CDC), by the Delaware Department of Health and Human Services (DDH), have increased almost every year since 1987. There were six (6) cases in 1987, 25 cases in 1989, 54 cases in 1989 [sic], 73 cases in 1991, and 106 cases in 1994 (references 4, 6, and 7, Appendix A). The lack of a rapid, sensitive, reliable, and cost- effective diagnostic test for LD results in proactive treatment before case confirmation and, consequently, under-reporting. The increased burden of reports on medical treatment facilities may also be a factor. Personnel concerned with LD prevention and control should not assume that human risk of LD has changed based solely on numbers of reported cases. c. Epidemiologic information from the state Department of Health and Human Services (DDH) indicates that there were 106 cases of LD reported from Delaware in 1994 (including 7 cases from Kent County, wherein DAFB is located). Delaware physicians have been reporting gradually increasing numbers of human LD cases to CDC, from 6 cases in 1987 to the 106 cases reported in 1994. There were no cases of Rocky Mountain spotted fever (RMSF) reported to CDC from Delaware in 1994. No human cases of LD or any other tick-borne disease have yet been reported from DAFB itself. 6. METHODS a. Deer examinations. The heads, ears, necks, and briskets of a portion of hunter-killed white-tailed deer (Odocoileus virginianus Zimmermann) were examined for the presence of ticks. The hair of stated areas was rubbed against the direction of its normal lay, using the edge of one or both hands. If ticks were detected, they were pulled off using fine-tipped forceps, placed into plastic vials, and returned to the Activity for identification and testing. b. Serum collection and testing. Blood which had pooled in deer body cavities was collected using clean, wide-tipped 4mL., disposable plastic pipettes, into 7mL. glass tubes, held for greater than or equal to 1 hour at ambient temperature (greater than or equal to 40 degrees F; less than or equal to 90 degrees F) to clot, and spun at greater than or equal to 1,500 rpm for greater than or equal to 5 min. The serum was drawn off into small plastic vials, labeled, frozen, and shipped to this Activity on dry ice (-32 degrees C). Sera were later shipped, on dry ice, to the DOD Veterinary Laboratory, ATTN: MCVS-SCL-D, 2472 Schofield Road (Bldg. 2632), Fort Sam Houston, Texas 78234-6232. They were tested via Indirect Fluorescent Antibody (IFA) techniques to detect the presence of any antibodies that the deer may have developed against B. burgdorferi. If the sample showed a "positive" response at a 1:128 serum dilution, as compared to a known positive standard, the deer from which the sample was drawn was considered to have been infected with B. burgdorferi. c. Tick collection and testing. Ticks were collected from deer as described in paragraph 6.a., above, returned to this Activity, identified, and tested via DFA techniques, as detailed by Piesman et al. (1986; reference 8, Appendix A), for the presence of B. burgdorferi. 7. RESULTS. (Also see Appendices B and C) a. A total of 495 Lyme disease (LD) vector ticks, I. scapularis Say, were collected from 52 of 58 deer examined at the Little Creek check station on 11 November 1994. Twenty-three (23) of the 495 ticks (4.6%) tested were positive for B. burgdorferi via DFA assays. An additional 25 ticks (5.1%) tested positive for Borrelia spp. b. Seven (7) of 43 deer serum samples collected (16.3%) tested positive (titer greater than or equal to 128) for antibodies against B. burgdorferi. 8. DISCUSSION. So far, no vector ticks nor human cases of LD have been reported from DAFB. However, increasing numbers of human LD cases reported from Delaware, and at least seven (7) human LD cases reported in 1994 from Kent County (Co), in which DAFB is located, imply that the potential for LD acquisition around (and on) DAFB is increasing. This justifies continued LD surveillance and prevention efforts at DAFB. 9. CONCLUSIONS. The above surveillance results, along with the 106 human LD cases reported in 1994 from Delaware (seven from Kent Co.), and epidemiologic information discussed in Wolfe et al. (1994; reference 7, Appendix A), all support the conclusions that the risk of humans acquiring LD in the immediate vicinity of DAFB (and possibly on the base itself) is high. The total absence of surveillance information from DAFB precludes any more precise statement about such risks on the base itself. 10. RECOMMENDATIONS. a. Periodically remind and retrain all military, civilian, and dependent personnel at DAFB concerning the information on repellents which is contained in Appendices D, E, and F of this report. b. Assist this Activity, or take other steps, to ensure the conduct of periodic (suggested annual) surveys of deer, small mammals, or the environment for host-seeking ticks, and evidence of the presence and prevalence of B. burgdorferi, to determine the risk level of contracting LD at DAFB. c. Report any LD cases to HQ, AFMOA/SGPA at Bolling AFB, and to the DDH, through the local (municipal or county) public health department (AFI 48-102). The DDH Division of Public Health can be reached at (302)739-5617. 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, ergonomic evaluation, sanitation and hygiene, and installation industrial hygiene management is available, and may be requested from USACHPPM, DSA-North at DSN 923- 6502/5281/6205, or commercial (301)[677-]6502/5281/6205. [signed by] Richard N. Johnson, MAJ, MS for HAROLD J. HARLAN, Ph.D., B.C.E. O.R.I.S.E. Intern for Lyme Disease Research Entomological Sciences Division ----- APPENDIX A REFERENCES 1. AFI 48-102, Aerospace Medicine - Medical Entomology Program, 6 December 1993. 2. DOD Directive 4150.7, Department of Defense Pest Management Program, 24 October 1983. 3. Armed Forces Pest Management Board Technical Information Memorandum No. 26, Lyme Disease: Vector Surveillance and Control, March 1990. 4. Lyme Disease Surveillance Summary, Vol. 4, No. 3, Centers for Disease Control and Prevention, June 1993. 5. Oliver, J. H. Jr., M. R. Owsley, H.J. Hutcheson, A. M. James, C. Chen, W. S. Irby, E. M. Dotson, and D. K. McLain. 1993. Conspecificity of the Ticks Ixodes scapularis and Ixodes dammini (Acari: Ixodidae). J. Med. Entomol., 30(1): 54-63. 6. Summary of Notifiable Diseases, United States 1994. Morbid. Mortal. Weekly Rept., Vol. 43 (No. 53): pp. 38, 49, and 69-80 (October 6, 1995). 7. Wolfe, D., C. Fries, K. Reynolds, and L. Hathcock. 1994. The Epidemiology of Lyme Disease in Delaware 1989-1992. Delaware Med. J., Vol. 66 (No. 11): 603-606. 8. Piesman, J., T. N. Mather, S.R. Telford III, and A. Spielman. 1986. Concurrent Borrelia burgdorferi and Babesia microti infection in nymphal Ixodes dammini. J. Clin. Microbiol. 24: 446-447. 9. Barbour, A. G., S. L. Tessier, and W. J. Todd. 1983. Lyme disease spirochetes and ixodid tick spirochetes share a common surface antigenic determinant defined by a monoclonal antibody. Infect. Immunol., 41: 795-804. ----- APPENDIX B DATA SUMMARY SHEET U.S. ARMY CENTER FOR HEALTH PROMOTION AND PREVENTIVE MEDICINE DIRECT SUPPORT ACTIVITY - NORTH LYME DISEASE RISK ASSESSMENT NO. 16-07-2709-95 DOVER AIR FORCE BASE, DELAWARE 11 NOVEMBER 1994 # Deer Examined 58 # Deer with Ixodes scapularis[1] 52 # Deer with Ticks 52 # Deer Serum Samples Tested 43 # Deer Serum Samples Positive[2] 7 # Human Lyme Disease Cases, 1994 - Kent Co., DE[3] 7 # Human Lyme Disease Cases, 1994 - Delaware[4] 106 ------------------------------------------------------------------------ 1 Ixodes dammini Spielman, Clifford, Piesman, and Corwin and Ixodes scapularis Say were synonymized by Oliver et al. (1993; reference 5, Appendix A). 2 Screening dilution level greater than or equal to 1:128 (= titer greater than or equal to 128). 3 Kent Co., DE, includes all of DAFB, as well as the sites from which deer were sampled in this study. 4 Based on reference 6., Appendix A, of this report. ----- APPENDIX C TICK TESTING AND SERUM TESTING RESULTS DOVER AIR FORCE BASE, DELAWARE 11 NOVEMBER 1994 Table C-2. Ixodes scapularis collected from 52 of 58 white-tailed deer examined were tested via DFA[1] for Borrelia spp. and Borrelia burgdorferi (only adult ticks were collected). ------------------------------------------------------------------------ Borrelia spp. Borrelia burgdorferi -------------------- -------------------- # Collected # Tested # + % + # Tested # + % + MALES 206 205 8 3.9 205 4 3.4 FEMALES 290 290 17 5.9 290 1 5.6 ===== ===== ==== ===== ===== === ===== TOTAL 496 495 25 5.0 495 5 4.6 ------------------------------------------------------------------------ 1 Direct Fluorescent Antibody (DFA) testing method (see reference 8, Appendix A) Table C-2. Serum Samples from nine deer tested via IFA[2] for antibodies against Borrelia burgdorferi. ------------------------------------------------------------------------ B. burgdorferi ------------------------ # Collected # Tested # + % + TOTAL 43 43 7 16.3 ------------------------------------------------------------------------ 2 Indirect Fluorescent Antibody (IFA) testing method (see reference 9, Appendix A) ----- 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- borne diseases" cards (GTA-8-5-56), pamphlets, and fact sheets. b. Notifications in the installation newsletter, local media, and post electronic media (e.g., closed-circuit TV), especially prior to the high-risk months (April-July). c. Making available, for viewing, the videos "Lyme Disease: A Growing Threat (FAUPIN No. 504494DA, Army TVT No. 8-196) and "Application of the Arthropod Repellent System" (No. 708575, Army TVT No. 8-232). 2. Submit any collected tick specimens (both field-collected or ticks that have been removed from individuals) alive for identification and DFA testing to USACHPPM, DSA-North, Fort Meade, MD 20755-5225. 3. Stock Permethrin Arthropod Repellent (NSN 6840-01-278-1336, box of 12 cans for $36.99), and 3M[1] 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)] via the new Army medical surveillance system, 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 done in early summer when I. scapularis nymphs (the life stage responsible for most human Lyme disease infections) are actively seeking hosts. 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. Clear such sites in low risk months (January-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 non-chemical control techniques (e.g., brush removal, mowing, raking) do not provide adequate control. -------------------------------------- 1 3-M 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 prices 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), NSN 6840-01-0284-3982. This is for application to exposed skin, 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. Approximately 75% of one can should [be] applied to each field uniform, and the remainder used to treat other items (e.g., mosquito netting). This 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 of one bottle are added to 2 gallons of water and applied with a 2-gallon sprayer (like the ones in a field sanitation kit) at a pressure of 55 psi, to field uniforms, mosquito netting, or tent fabric to provide protection from ticks, biting flies, and other insects. Since many sprayers are not equipped with the required pressure gauge (NSN 3740- 01-332-8746), it may be necessary to obtain this type of pressure gauge and filter (NSN 4330-01- 332-1639), to retrofit an available sprayer. Proper application, followed by complete drying of the fabric, can provide protection for the normal life of the uniform (180 days in the field), six launderings of mosquito netting, or 6-9 months effectiveness for tent fabric, depending on the climate of deployment site(s). 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" cards (GTA 8-5-56) should be ordered through normal military publications channels. Limited numbers of these cards may be obtained from the Entomological Sciences Division, USACHPPM, DSA-North, at DSN 923-5281 or commercial (301)677-5281. ----- APPENDIX F FACT SHEET - MOSQUITO AND TICK REPELLENTS 1. Repellents containing DEET (N,N-Diethyl-3-methylbenzamide, formerly N,N-Diethyl-m-tolumide) offer good protection against mosquitoes, and are made for application to skin. 2. Repellents containing Permethrin offer excellent protection against ticks, and are formulated for application to clothing. 3. DEET also offers protection against ticks, keeping them from attaching to treated skin (sometimes for long periods). Ticks do not generally attach in exposed areas, the primary areas to which DEET is to be applied (refer to any given product's label directions). 4. Permethrin, conversely, offers considerable protection against many mosquito species, but it can't be applied to exposed skin (refer to any given product's label directions), the main area(s) mosquitoes usually bite. Permethrin is useful for treating bed netting. 5. Combined use of DEET on exposed skin (as for mosquito repellency) and Permethrin on clothing (as for tick repellency) offers maximum protection against both these (as well as many other) pests. Always read and follow the label before using any compound. 6. Do NOT use flea or tick collars. A toxic reaction can result. Humans have many sweat glands in their skin that can serve as avenues for chemical absorption. Dogs (and cats) on the other hand, do not have sweat glands in their skin and cool themselves by panting. In addition, most breeds of these pets have a thick hair layer (barrier) which protects their skin from direct contact with collars. Humans have very limited hair covering. 7. Various lotion products claim protection against mosquitoes. Professional literature both supports and refutes benefits from lotions. Controlled tests have shown that mineral oil, a major component of most such lotion products, does reduce biting by several species of mosquitoes on areas of treated skin. However, this reduction in biting is small when compared to the reduction by an equal amount of DEET in concurrent tests by USDA labs. 8. Controlled tests have shown that products containing high concentrations (greater than or equal to 50%) of DEET do not offer greater protection than products containing 30-50% DEET. 9. 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 wearing loose- fitting long-sleeved shirts in summer. - Tuck pants legs inside tops of socks or boots. - Wear light-colored clothing to make ticks easier to see as they crawl. - Plan ahead and treat clothing with permethrin before starting your outdoor activity. Permethrin binds with fabric and is persistent through several detergent washings. (Dry cleaning will remove it immediately.) - Store treated clothing in a plastic bag to help preserve repellent effectiveness, and to help identify which clothing has been treated. -----