PEST MANAGEMENT STUDY, IOWA ARMY AMMUNITION PLANT, MIDDLETOWN, IOWA, 29 JULY-2 AUGUST 1991 DEPARTMENT OF THE ARMY US Army Environmental Hygiene Activity-West Fitzsimons Army Medical Center Aurora, Colorado 80045-5001 [Seal of Department of Defense, United States of America] REPLY TO ATTENTION OF: HSHB-AW-P (40-5F) 18 November 1991 PEST MANAGEMENT STUDY NO. 16-66-5037-91 IOWA ARMY AMMUNITION PLANT MIDDLETOWN, IOWA 29 JULY-2 AUGUST 1991 1. REFERENCES. See Appendix A for a list of references. 2. AUTHORITY. AEHA Form 250-R, U.S. Army Materiel Command, 12 February 1991. 3. PURPOSE. The purpose in performing this study was to survey for Lyme disease vectors, determine the prevalence of the infective agent, Borrelia burgdorferi, in rodents and ticks, and to determine the potential for Lyme disease to become endemic on Iowa Army Ammunition Plant (IAAP). See Appendix B for other assistance that can be obtained from the U.S. Army Environmental Hygiene Activity-West (USAEHA-W). 4. GENERAL. a. This study was conducted by Dr. Lester D. Hale, Entomologist and Mr. William Irwin, Biological Laboratory Technician, this Activity. The Survey Officers discussed major findings and recommendations with IAAP personnel. A list of personnel contacted is found in Appendix C. b. Personnel assisting Dr. Hale and Mr. Irwin during the study were: Mr. Allen Buren, Security Specialist and Lyme Disease Coordinator; Mr. Steven Busse, Area Safety Engineer III; Ms. Vicki Dreckmeier, Mail Clerk; and Ms. Kelly Vogel, Mail Clerk, Mason & Hanger - Silas Mason Co., Inc. c. The field survey portion of the Lyme disease study was conducted at IAAP on 29 July-2 August 1991. d. This study also provided training for IAAP personnel. On-the-job training conducted during the field survey portion of the study included: vector surveillance procedures, tick surveillance methods, small mammal trapping, and ear tissue biopsy sample methodology. A Lyme disease video on the epidemiology of Lyme disease and the personnel protective measures for this disease was shown to the IAAP personnel. 5. BACKGROUND. a. Lyme disease is a multi-systemic infectious disease caused by the spirochete, Borrelia 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 220 cases of Lyme disease contracted on Department of Defense (DOD) installations from 1987 through 1989. During 1989/1990, three U.S. Army soldiers (one from New Jersey and two from Wisconsin) received medical discharges attributed to the effects of Lyme disease. b. The need to protect soldiers and other personnel working on DOD installations (particularly in the east) has increased with the spread of Lyme disease. c. There were 16 provisional cases of Lyme disease reported to Centers for Disease Control from Iowa in 1990. Two cases of Lyme disease were reported from Des Moines County (one in 1983 and one in 1987). One human case of Lyme disease was reportedly acquired on IAAP by a National Guardsman during training exercises in April 1987. The Des Moines county Public Health Nurse stated that no additional cases have been reported in Des Moines County since the 1987 case. d. The IAAP is located 11 miles west of the Mississippi River in Des Moines County, Iowa. It measures approximately 30 square miles in area. It is comprised of rolling terrain with interspersed hardwood, deciduous forest, and open land and pasture land which was leased for agriculture. Most administrative and industrial operations are located on the northern half of the installation. The southern half is more wooded, being deeply cut with streams draining into the Skunk River along the southern boundary. Iowa Army Ammunition Plant is used by U.S. Army National Guard and Reserve Component military units for maneuvers and training. The primary users of IAAP were National Guard and Army Reserve units from Iowa and Illinois. Over the past three years, the volume of training supported by IAAP has averaged about 7,000 soldiers per year. Mason & Hanger - Silas Mason Co., was the contract operator of the Government-owned, contractor-operated ammunition plant. 6. METHODS. a. Field Survey Procedures. (1) Tick Surveys. Ticks were collected using tick drag cloths and/or tick flags, and carbon dioxide traps. Ticks were also removed from the ears of trapped rodents on IAAP. All ticks were kept alive by placing them in water moistened vials as described in the USAEHA-W, Entomological Sciences Division (ESD) Standing Operating Procedures (SOP) No. 6 and No. 8. For each collection site, all collected ticks were identified, counted, and placed into marked vials. Ticks collected at different collection sites were kept segregated and placed into separate marked vials. The collected ticks were hand-carried to the USAEHA-W, ESD Laboratory. (a) Tick Drag Technique. Two narrow boards (1x2x36-inch) were attached on opposite ends of a 3x3 foot of white flannel cloth. A cord was fastened to the ends of one board. The cloth was then pulled slowly over vegetation for approximately 10 meters before examination for attached ticks. Ticks were then removed from the cloth and placed in a marked vial for that particular dragging operation. Approximately 1200 linear meters were covered by team members at the different collection sites. (b) Tick Flag Technique. 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. Attached ticks were then removed from the cloth and placed in a marked vial for each collection site. Approximately 400 linear meters were covered by team members doing the flagging. (c) Carbon Dioxide Traps. A 2x2 foot piece of white flannel cloth was placed on the ground and the edges were weighted down with stones. An aluminum-foil covered pie plate was placed upside down in the middle of the cloth. Approximately 2 pounds of dry ice were wrapped in newspaper and placed on top of the pan. The area around each trap and the cloth were checked for ticks after 3 to 4 hours. (2) Rodent Surveys. Rodents trapped at IAAP were identified using "A Field Guide to the Mammals, North America, north of Mexico" (Reference 3). (a) Small mammals were captured in small live traps (3x3x10 inches) on IAAP. Several trapping locations were selected on the installation. One or more trap lines were set in each area. The traps were usually located near stream beds and ponds with traps located approximately 10 meters apart. The traps were set only one night at each location using at least 10 traps. (b) All mammals were anesthetized before removing ticks and taking ear tissue biopsies. 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 USAEHA-W, ESD SOP No. 7. (c) Ticks found on mammals were removed for bioassay. b. Laboratory Assay Procedures. (1) All ticks collected during the survey and ear tissue biopsies from rodents trapped on IAAP were hand-carried to the USAEHA-W, ESD Laboratory for Lyme disease bioassay. (2) The midguts of 40 Lone Star ticks, Amblyomma americanum, were dissected and examined using darkfield and immunofluorescent microscopy for spirochetes. Twelve tick pools, using the homogenate from larvae or nymphs of Lone Star ticks, ground in a tissue grinder, were cultured in modified Barbour-Stoenner-Kelly (BSK) II media for spirochetes. Nineteen ear tissue biopsies from trapped rodents were cultured in BSK II media. Tissue samples from the tick pools and from the ear tissue biopsies, cultured in BSK II medium, were examined under the microscope every 7 days for 30 days for spirochete growth. If no spirochetes were found during this period, the ear tissue was considered to be negative for Borrelia burgdorferi. 7. FINDINGS AND DISCUSSION. (a) Survey Results. (1) Ticks were collected from humid or wet sites such as stream banks, ponds, and near Mathes Lake at the Boy Scout Camp. Seventeen American dog ticks, Dermacentor variabilis, and 643 Lone Star ticks were collected by either dragging or flagging or carbon dioxide (C02) traps. The Lone Star ticks examined by darkfield and immunofluorescent microscopy in the laboratory analysis were negative for Borrelia burgdorferi. Table 1 shows the sites, map coordinates, species, and number of each of the life stages of ticks collected on IAAP during tick drags/flags and carbon dioxide traps. (2) Table 2 shows the rodents captured on IAAP and the number of attached ticks removed. One adult American dog tick was collected from a roadkilled red squirrel. Nineteen midguts of Lone Star ticks were examined by darkfield and immunofluorescent microscopy and found to be negative for Borrelia burgdorferi. (3) Twelve tick pools (consisting of 5-20 ticks per pool) were cultured in BSK II media. All cultured tick pools were found to be negative for Borrelia burgdorferi. (4) The deer tick, Ixodes dammini, the vector for Lyme disease in the midwest, was not found among the collected ticks. (5) Nineteen ear tissue biopsies, taken from the rodents captured on IAAP (Table 2), were cultured in BSK II media. All biopsies were negative for Borrelia burgdorferi, suggesting that the spirochete had not circulated within the limited population sampled at IAAP. TABLE 1. Number of American dog and Lone Star ticks, collected from drags, flags, and carbon dioxide traps at Iowa Army Ammunition Plant. NUMBER OF TICKS ------------------------------------------- SITE NAME OF SITE D. variabilis A. americanum ------------------------------------------------------------------------ drags/flags CO2 traps drags/flags CO2 traps ----------- --------- ----------- --------- 1 D Road Creek 0 3a 0 0 (649694,4518333)* 2 G Road Pond 5a 5a 4n 2n (651222,4519055)* 3 Boy Scout Camp 0 0 1a,8n 1n (647110,4515415)* 323(l) 4 Pistol Range Creek 2a 0 1n,7(l) 1n (648166,4513444)* 5 K Road Bridge 0 0 0 0 (652070,4514222)* 6 Sewage Disposal Creek 0 0 0 25n (650194,4516195)* 7 I Road Bridge 2a - 4n - (649486,4516944)* 8 Picnic Area 0 0 0 0 (645612,4520473)* 9 Explosive Disposal Creek 0 0 0 0 (652639,4517500)* 10 N. G. Training Site - 0 1a,2n - (643750,4516083)* 268(l) 11 P Road Creek - 0 - 1n (652610,4517528)* 12 P Road Pond - 0 - 1n (653944,4517432)* ------------------------------------------- TOTAL TICKS COLLECTED 9a 8a 2a,19n,598(l) 31n * Map coordinates given as longitude and latitude: based on Iowa Army Ammunition Plant General Layout Map, dated 1957. a - Adult Tick, n - Nymphal Tick, (l) - Larval Tick TABLE 2. Number of Amblyomma americanum removed from rodents on Iowa Army Ammunition Plant. RODENTS CAPTURED (# RODENTS)* ---------------------------------------------- White-footed mouse Deer mouse SITE NAME OF TRAP SITE (Peromyscus leucopus) (Peromyscus maniculatus) ----------------------------------------------------------------------- 1 D Road Creek (2) (649694,4518333) 5(l) 3 Boy Scout Camp (4) (3) (647110,4515415) 6n,25(l) 1n,10(l) 6 Sewage Disposal Creek (6) (650194,4516195) 2n,26(l) 9 Explosive Disposal Creek (2) (2) (652639,4517500) 11(l) 1n,15(l) * An adult Dermacentor variabilis was removed from a red squirrel, Tamiasciurus hudsonicus, (the squirrel was a roadkill at the K-Road Bridge site). n - Nymphal Tick, (l) - Larval Tick ------------------------------------------------------------------------ b. Lyme Disease Risk. (1) Previous studies (Appendix A, Reference 6) on Lyme disease during deer hunts were conducted during 1986 and 1987 on IAAP by Dr. Nixon Wilson. Only one deer tick nymph (0.4 percent) was removed from deer during the 1986 deer hunt, and none were found during the 1987 deer hunt. Two adult deer ticks were identified by Dr. Wilson from other ticks collected from IAAP during the period from April 1987 until July 1988. During the 1988 deer hunt at IAAP (Appendix A, Reference 6), this Agency removed two deer ticks (one adult and one nymph) from 310 deer examined. During this study a total of 163 deer sera were screened for specific antibody to the Lyme disease spirochete. Seven (4 percent) of the deer tested positive for Borrelia burgdorferi using the immunofluorescent antibody (IFA) test to determine the prevalence of infection. (2) The field survey portion of this study produced many ticks from dragging and flagging, from carbon dioxide traps, and from trapped rodents. This information reflected comments from installation personnel that an abundance of ticks were encountered by people exposed to outdoor field environments on IAAP. (3) The ticks that were found during this study, the American dog and the Lone Star ticks have not been implicated as vectors of Lyme disease. The deer tick, a proven vector of Lyme disease, was not found during this study. (4) No Lyme disease spirochetes were recovered from either the ticks collected or from the ear tissue samples taken from rodents in this study. Considering that no cases of Lyme disease have been reported since the one human Lyme disease case diagnosed in 1987 and the positive deer titers for the spirochete in the 1989 study, it is presumed that based on all available information, the spirochete is extremely low on IAAP at the present time. (5) The proper conditions for endemic Lyme disease exist at IAAP. The necessary components to support an endemic focus include the deer tick, a well-established deer herd, the presence of the white-footed mouse, and a wooded habitat. There may be several reasons why no deer ticks were found during the field survey i.e., the tick was not active during this time of year, local tick foci were missed, the tick has not established itself in large numbers since the first tick was collected in 1986 on the installation, or since IAAP has been reported to be on the southern edge of the deer tick's established geographic range, it has not become well established on the installation. (6) To have a human health risk from Lyme disease, individuals must be exposed to and bitten by infected tick vectors. Although no ticks or disease organisms were found during this study, both have been previously reported on the installation. Despite many unanswered questions, enough evidence exists to suggest that the incidence of Lyme disease will continue to be low at IAAP. However, the potential for the level of Lyme disease could rapidly change if the tick vector populations dramatically increase on the installation. Even though Lyme disease was not endemic during this study on IAAP, personal protective measures to guard against tick bites would be prudent. Lyme disease incidence in counties surrounding these installations should provide valuable information should this disease increase in scope within the State of Iowa. 8. CONCLUSIONS. Ixodes dammini, the tick vector species for Lyme disease in Iowa, was not collected at IAAP during this study. Borrelia burgdorferi, the causative agent for Lyme disease, was not found in the tick and small mammal populations sampled. Personnel training, working or residing on IAAP appear to be a very low risk for acquiring Lyme disease. Iowa Army Ammunition Plant personnel were exceptionally receptive to information on Lyme disease and personal protective measures for prevention of tick bites. [signature] LESTER D. HALE Entomologist Entomological Sciences Division APPROVED BY: [signature] RONALD J. RAKICKAS LTC, MS Chief, Entomological Sciences Division APPENDIX A REFERENCES 1. USAEHA-W, ESD SOP No. 6, 24 April 1991, Tick Collection Procedures. 2. USAEHA-W, ESD SOP No. 8, 25 April 1991, Small Mammal Tick and Ear Tissue Collections. 3. Burt, W. H. and R. P. Grossenheider, A Field Guide to the Mammals, North America, north of Mexico, Third Edition, 1976, Houghton Mifflin Company, Boston, 289pp. 4. 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. 5. USAEHA-W, ESD SOP No. 7, 25 April 1991, Procedures for Trapping and Handling Small Mammals. 6. Memorandum, this Agency, HSHB-MR-EMG, 6 March 1990, subject: Installation Pest Management Consultation No. 16-44-0520-90, Iowa Army Ammunition Plant, Middletown, Iowa, 2-5 December 1988. 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 at 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 943-3318 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 Environmental Hygiene Agency, 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 PERSONNEL CONTACTED 1. Ms. Barbara Baker Public Health Nurse Des Moines County Health Department Commercial (319) 753-8217 2. LTC Duane Brandt* Commander, IAAP DSN 585-7200 3. Ms. Judy M, Brunson*+ Chief, Industrial Division DSN 585-7702 4. Mr. Allen Buren*+ Security Specialist and Lyme Disease Coordinator Mason & Hanger - Silas Mason Co., Inc. DSN 585-7005 5. Mr. Steven Busse Area Safety Engineer III Mason & Hanger - Silas Mason Co., Inc. DSN 585-7218 6. Ms. Vicki Dreckmeier Mail Clerk Mason & Hanger - Silas Mason Co., Inc. DSN 585-7131 7. Ms. Judith E. Morgan*+ Industrial Specialist DSN 585-7802 8. CPT Robert B. Reeves, Jr.* Executive Officer, IAAP DSN 585-7201 9. Ms. Kelly Vogel Mail Clerk Mason & Hanger - Silas Mason Co., Inc. DSN 585-7151 ----------------- * - Individual received a inbriefing + - Individual received an exit briefing