LYME DISEASE RISK ASSESSMENT, VANDENBERG AIR FORCE BASE, CALIFORNIA, 6-10 FEBRUARY 1995 DEPARTMENT OF THE ARMY U.S. Army Center For Health Promotion And Preventive Medicine (Provisional) Direct Support Activity - West Fitzsimons Army Medical Center Aurora, Colorado 80045-5001 [Seal of Department of Defense, United States of America] REPLY TO ATTENTION OF: MCHB-AW-P (40-5f) 20 April 1995 LYME DISEASE RISK ASSESSMENT NO. 16-09-3109-95 VANDENBERG AIR FORCE BASE, CALIFORNIA 6-10 FEBRUARY 1995 1. REFERENCES. See Appendix A for a list of references. 2. AUTHORITY. USAEHA Form 250-R, Department of the Air Force, 9 January 1995. 3. PURPOSE. The purpose in performing this risk assessment was to survey for Lyme disease vectors, to determine the prevalence of the infective agent, Borrelia burgdorferi, in rodents and ticks, and to assess the risk of Lyme disease to Vandenberg Air Force Base (VAFB) personnel. See Appendix B for other assistance that can be obtained from the U.S. Army Center for Health Promotion and Preventive Medicine (Provisional), Direct Support Activity-West [USACHPPM (Prov), DSA-W]. 4. GENERAL. a. Risk Definition. The term "risk", as used in this Report, is a non- statistical determination of qualitative and quantitative information available to evaluate the potential to acquire Lyme disease. To the extent available, information evaluated includes the following elements of the Lyme disease cycle: (1) History of Lyme disease in the area. (2) The presence or absence of the tick vector, Ixodes pacificus, and the mammalian 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 or in the mammalian reservoir host population. (4) The presence of antibodies to B. burgdorferi in the mammalian host population. Criteria for risk categorization follow: Low risk - Some elements of the Lyme disease cycle identified in nearby areas but not on the installation. Moderate risk - Elements of Lyme disease cycle identified from the installation or human cases of Lyme disease identified from the local area. High risk - All elements of the Lyme disease cycle are present on the installation. b. Mr. William E. Irwin, the Project Officer, and Mr. Frederick J. Harrison, Entomological Sciences Division (ESD), USACHPPM (Prov), DSA-W, discussed major findings and recommendations with VAFB Public Health personnel regarding Lyme disease and other tick-borne diseases, as well as hantavirus. A list of personnel contacted and personnel assisting the Survey Officers during the risk assessment is found in Appendix C. c. The field survey portion of the Lyme Disease Risk Assessment was conducted at VAFB during 6-10 February 1995. d. This study also provided training for the VAFB Public Health personnel, and two State of California Department of Health Services officials. On-the-job training conducted during the field survey portion of the risk assessment included vector surveillance procedures, tick surveillance methods, small mammal trapping, and ear biopsy procedures. Vandenberg AFB personnel were exceptionally receptive to information on Lyme disease and personal protective measures for prevention of tick bites. e. Laboratory analyses of ticks and rodent ear biopsies were conducted between 13 February - 30 March 1995. 5. BACKGROUND. a. Lyme disease is a multi-systemic 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 need to protect soldiers and other personnel working on DOD installations has increased with the spread of Lyme disease. b. During 1994, there were 85 cases of Lyme disease reported from the State of California to the Centers for Disease Control and Prevention (Appendix A, Reference 1). Dr. Robert Murray, California Department of Health Services, stated that there were only 70 cases of Lyme disease confirmed from California in 1994. He also stated that only 10 cases of Lyme disease were confirmened from Santa Barbara County between 1991 and 1993, and there were no Santa Barbara County Lyme disease cases reported in 1994. c. Currently, the State of California Department of Health Services and Santa Barbara County Health Care Services are investigating a number of suspected Lyme disease cases in Santa Barbara County. According to Dr. Alan Chovil, Santa Barbara County Health Care Services, one patient originally diagnosed as having juvenile arthritis has shown a positive titer to Lyme disease. 6. METHODS. a. Field Survey Procedures. (1) Tick Surveys. The tick collecting methods at VAFB included tick flagging. A 3x3-foot piece of white flannel cloth was dragged over the tops of large vegetation (i.e., sagebrush) or was used on steep slopes. At each collection site, attached ticks were removed from the cloth and placed in a labeled vial. Approximately 3500 linear meters were covered by team members doing the flagging. Ticks were also removed from the ears of trapped rodents and several lizards (Appendix A, Reference 2 and 3). All ticks were kept alive by placing then in water-moistened vials and sent to the USACHPPM (Prov), DSA-W Entomological Sciences Division (ESD) Laboratory. For each collection site or rodent, all collected ticks were identified (Appendix A, Reference 4-6), counted, and separated into pools or processed individually. Certain ticks were sent to the National Tick Museum at Georgia Southern University, Statesboro, Georgia, for identification confirmation. (2) Rodent Surveys. Small rodents were captured to determine the presence of potential Lyme disease reservoir animals on VAFB by processing small ear biopsies to determine the presence of spirochetes in the rodents (Appendix A, Reference 3). Rodents trapped at VAFB were identified using "California Mammals" (Appendix A, Reference 7). All rodents were handled in accordance with the guidelines outlined in the National Institutes of Health Publication No. 85-23, revised 1985, "Guide for the Care and Use of Laboratory Animals", and USACHPPM (Prov), DSA-W, ESD Animal Use Protocols (Appendix A, References 8 and 9). (a) Rodents were captured alive in Sherman traps (3x3x10 inches) and in National traps (5x5x16 inches) on VAFB. At each site, several trapping locations were selected, and one or more trap lines were set in each area. The traps were usually located near the base of bushes or trees or near rodent nests or burrows with traps located approximately 10-20 meters apart. The traps were set in the evening and collected before 0900 the next morning (Appendix A, Reference 10). (b) Each rodent was anesthetized before removing any ticks or taking an ear biopsy. Each ear biopsy was placed in a labeled vial containing a glycerol/phosphate buffer solution and then frozen on dry ice. All biopsies were kept frozen until assayed for Lyme disease. (3) Specimen Handling Procedures. All ticks and ear biopsies collected were shipped overnight to the USACHPPM (Prov), DSA-W ESD Laboratory. b. Laboratory Assay Procedures. (1) BSK II Cultures: (a) Four western black-legged ticks, I. pacificus, nymphs collected from a western fence lizard, Sceloporus occidentalis, were processed for culturing. The resulting homogenate was inoculated into BSK II, liquid culture media specifically developed to promote the growth of the spirochete that causes Lyme disease. (b) Eighty-eight rodent ear biopsies were surface decontaminated and cultured in BSK II. Each inoculated culture was examined under the darkfield microscope every seventh day for 21 days for spirochete growth. If no spirochetes were found during this period, the samples were considered to be negative for B. burgdorferi. (2) Polymerase Chain Reaction (PCR): (a) Twenty-six pools of ticks were processed using PCR. These pools were set up with 1-10 individuals each. (b) Specific ear biopsy cultures were also processed using PCR. 7. FINDINGS. a. Tick Collections. During the field survey portion of this Lyme disease risk assessment, 84 ticks were collected by flags--35 adult I. pacificus and 49 adult Dermacentor occidentalis. Forty-five ticks were collected from lizards--44 I. pacificus and one D. occidentalis. Eighty- nine ticks were removed from trapped rodents (see Table). b. Rodent Collections. Seven species of rodents were captured at six sites on VAFB (see Table). The deer mouse was the most common rodent captured. c. Laboratory Results. Detailed information on the sites, species of ticks and rodents, and laboratory results are given in Appendix D. (1) Ticks. Twenty-six pools of ticks were analyzed using PCR techniques. Three pools were positive for B. burgdorferi. Two pools of ticks collected from flags at Space Launch Command 6 (SLC-6) were positive for the spirochete that causes Lyme disease--one pool of I. pacificus females, and one pool of D. occidentalis. The third positive tick pool was a single engorged I. pacificus larva collected from a Peromyscus maniculatus that was captured at Overlook Road at SLC-6. (2) Rodent Ear Biopsies. Eighty-eight rodent biopsies were cultured in BSK II media for spirochetes. While none of the cultures showed signs of spirochetes growth, nine samples were suspected of having non-motile spirochetes. These nine samples were processed and tested by using the PCR techniques. Three of these samples were positive for B. burgdorferi. These three samples included a P. californicus and a P. maniculatus captured at the San Antonio Picnic Grounds and a P. maniculatus cpatured at the Santa Yanez [sic] River site 8. LYME DISEASE RISK AND DISCUSSION. a. Lyme disease spirochetes were recovered from both ticks and from the rodent ear tissue samples collected during this assessment. b. The categorization established by the Risk Definition, as defined in paragraph 4a, was used to determine the human health risk from Lyme disease at VAFB. The data collected during this assessment indicate that all of the criteria for acquiring Lyme disease were present; the tick vector, the pathogen, and the existence of human cases in the immediate area. Although no human cases of Lyme disease have been diagnosed as originating on VAFB, personal protective measures to guard against tick bites would be prudent. Risk of contracting Lyme disease can be minimized by the proper wearing of clothing, avoiding areas known to harbor high tick populations, and the use of repellents (see Appendix E for repellent products available in the Defense General Supply Center or Self-Service System). General Lyme disease reduction measures can be found in Appendix F. c. This Activity has made collection materials available to VAFB Public Health personnel so that tick surveillance could be continued throughout the year. Ticks may be sent to our USACHPPM (Prov), DSA-W, ESD Laboratory at any time; we will identify and analyze submitted specimens for Lyme disease. Continuing studies such as these should further define the presence and distribution of ticks and the risk of acquiring Lyme disease on VAFB. Table. Number of Ixodes spp. Ticks Removed from Rodents at VAFB, California --------------------------------------------------------------------------- Ixodes I. Collection Site No. Rodent Species pacificus angustus --------------------------------------------------------------------------- San Antonio Picnic Grounds 18 Peromyscus maniculatus 10L 1L,1F (Deer mouse) 12 P. californicus 4L 0 (California mouse) 9 P. truei (Pinon mouse) 3L 0 4 Neotoma fuscipes 1N 0 (Dusky-footed woodrat) 1 Microtus californicus 0 0 (California vole) 1 Reithrodontomys megalotis 3L 0 (Western harvest mouse) Military Police Dog 11 P. maniculatus 4L 0 Training Area (Deer mouse) 2 P. californicus 0 0 (California mouse) 1 P. truei (Pinon mouse) 0 0 1 Dipodomys agilis 0 0 (Pacific kangaroo rat) Santa Ynez River at 19 P. maniculatus 1L,1F 0 13th Street (Deer mouse) 4 P. californicus 0 0 (California mouse) 2 R. megalotis 0 0 (Western harvest mouse) West of Obstacle Course 6 P. maniculatus 3L 0 (Deer mouse) 1 P. californicus 0 0 (California mouse) 2 N. fuscipes 0 0 (Dusky-footed woodrat) Space Launch Command 9 P. maniculatus 29L,1N,4F 1L,4N,4F (Deer mouse) 2 P. californicus 4L 0 (California mouse) Overlook Road at SLC 6 2 P. maniculatus 7L,1F 0 (Deer mouse) 1 N. fuscipes 1L 1F (Dusky-footed woodrat) ----- ------------------- TOTALS 108 69L,2N,6F 2L,4N,6F L - Larva, N - Nymph, F - Female --------------------------------------------------------------------------- 9. CONCLUSIONS. The western black-legged tick, I. pacificus, the tick vector species for Lyme disease in California, was collected at VAFB. Borrelia burgdorferi, the causative agent for Lyme disease, was found on the installation. Personnel training, working, or residing on VAFB are at High risk for acquiring Lyme disease. Implementation of personal protective measures for all military, civilians, and dependents using VAFB for outdoor training or recreation is recommended. [signature] WILLIAM E. IRWIN Lyme Disease Investigator APPROVED BY: [signature] FREDERICK J. HARRISON, JR. Chief, Entomological Sciences Division APPENDIX A REFERENCES 1. Morbidity and Mortality Weekly Report, Vol 43, No. 51 & 52, January 1995, Massachusetts Medical Society, p. 968. 2. U.S. Army Environmental Hygiene Agency, Direct Support Activity-West (USAEHA-W), Entomological Sciences Division (ESD) SOP No. 6, 24 April 1991, Tick Collection Procedures. 3. USAEHA-W, ESD SOP No. 8, 25 April 1991, Small Mammal Ticks and Ear Tissue Collections. 4. Webb, J.P. Jr., S.G. Bennett, and G.L. Challet, "The Larval Ticks of the Genus Ixodes Latreille (Acari: Ixodidae) of California", June 1990, Bull. Soc. Vector Ecol., 15(1): 73-124 5. Cooley, R.A. and G.M. Kohls, "The Genus Ixodes in North America", 1945, National Institute [sic] of Health Bulletin No. 184. 6. Brinton, E.P., D.E. Beck and D.M. Allred, "Identification of Adults, Nymphs and Larvae of Ticks of the Genus Dermacentor Koch (Ixodidae) in the Western United States", February 1965, Brigham Young University Science Bulletin. 7. Jameson, E.W. Jr., and H. Peters, "California Mammals", 1988, University of California Press, Berkeley, California. 8. National Institutes of Health Publication No. 85-23, revised 1985, "Guide for the Care and Use of Laboratory Animals", U.S. Department of Health and Human Services. 9. Hale, L.D., et. al., 10 May 1994, Lyme Disease Protocol 94/801A, "Laboratory Animal Clinical Investigation Project Fitzsimons Army Medical Center (Experimental)", US Army Environmental Hygiene Activity-West. 10. USAEHA-W, ESD SOP No. 7, 25 April 1991, Procedures for Trapping and Handling Small Mammals. APPENDIX B 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 Pest Management Consultant if you desire to request on-site assistance from our Activity. Technical 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 services are available from our parent organization, the U.S. Army Center for Health Promotion and Preventive Medicine (Provisional), 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 C FIELD SURVEY PERSONNEL CPT Bridget K. Carr, Chief, Public Health, 30th Medical Group/SGPM, Vandenberg AFB, CA. Mr. William E. Irwin, Project Officer, USACHPPM, DSA-West, Fitzsimons Army Medical Center, Aurora, CO. Mr. Richard M. Davis, Public Health Biologist, California Department of Health Services, Vector-Borne Disease Section, Ventura, CA. Mr. Minoo B. Madon, Public Health Biologist, California Department of Health Services, Vector-Borne Disease Section, Ontario, CA. SSG Thomas J. Martin, Public Health Technician, 30th Medical Group/SGPM, Vandenberg AFB, CA. SSG Vincent R. Paolucci, Public Health Technician, 30th Medical Group/SGPM, Vandenberg AFB, CA. SrA, Ceasar G. Garcia, Public Health Technician, 30th Medical Group/SGPM, Vandenberg AFB, CA. SrA, Mitchell T. Lawrence, Public Health Technician, 30th Medical Group/SGPM, Vandenberg AFB, CA. SrA, Rusty E. Mardis, Public Health Technician, 30th Medical Group/SGPM, Vandenberg AFB, CA. SPC Michael B. Watson, Environmental Health Technician, USACHPPM (Prov), DSA-West, Fitzsimons Army Medical Center, Aurora, CO. 1LT Ryan R. Reichenbacker, Entomologist, USACHPPM, DSA-West, Fitzsimons Army Medical Center, Aurora, CO. Mr. Fredrick J. Harrison, Jr., Chief, Entomological Sciences Division, USACHPPM (Prov), DSA-West, Fitzsimons Army Medical Center, Aurora, CO. APPENDIX D TICK LOG 1995 [Data omitted - data summarized in above report] 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 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 launderings of mosquito netting, and 6 to 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 U.S. Army Center for Health Promotion and Preventive Medicine (Provisional), Entomological Sciences Division. APPENDIX F 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. Notification in the installation newsletter, especially prior to the high-risk months (January-May). c. Making available for viewing video and 35mm slide format presentations on Lyme disease that are available from this Activity. 2. Submit any collected live tick specimens (both field-collected or ticks that have been removed from individuals) for identification and immunofluorescent staining or darkfield microscopy testing to the U.S. Army Center for Health Promotion and Preventive Medicine (Provisional), Direct Support Activity-West Entomological Sciences Division, 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 and the 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 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 Borrelia burgdorferi. Sampling should be performed in early January thru February when Ixodes pacificus nymphs (the life stage responsibile 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. Army Center for Health Promotion and Preventive Medicine (Provisional), ATTN: MCHB-MR-E, Aberdeen Proving Ground, MD 21010-5422, or by telephone at 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 dragging or flagging for ticks prior to use. Case-by-case surveillance is necessary due to the patchy distribution of I. pacificus. 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., August - November). 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