LYME DISEASE RISK ASSESSMENT, FORT DEVENS, MASSACHUSETTS, 1-3 DEC 1991 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) 05 MAY 1992 LYME DISEASE RISK ASSESSMENT NO. 16-61-A847-92 FORT DEVENS, MASSACHUSETTS 1-3 December 1991 1. REFERENCES. a. AR 40-5, Preventive Medicine, 15 October 1990. b. Technical Information Memorandum No. 26, Lyme Disease: Vector Surveillance and Control. Armed Forces Pest Management Board, March 1990. c. Lyme Disease Surveillance Summary, Vol. 3, No. 1, Centers for Disease Control, March 1992. 2. AUTHORITY. AEHA Form 250-R, HSC, 7 August 1991. 3. PURPOSE. To assess the risk of Lyme disease to Fort Devens personnel by examining deer for the tick vector, Ixodes dammini and to assay ticks for the Lyme disease etiologic agent, Borrelia burgdorferi, IAW para 10- 7.f., AR 40-5. 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. dammini) 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 risk - Some elements of the Lyme disease cycle identified in nearby areas but not on the installation. Moderate risk - Some elements of Lyme disease cycle identified from the installation or human cases of Lyme disease reported from the local area. High risk - All elements of the Lyme disease cycle present on the installation. b. Personnel Contacted. The purpose and methodology of this assessment were discussed in briefings with: MAJ Russell Hanson, Chief, Preventive Medicine Service (PVNTMED Svc), Medical Department Activity (MEDDAC), Fort Devens; and Mr. Norm Black, Chief, Land Management Branch, Directorate of Engineering and Housing (DEH), Fort Devens. c. Survey Conduct. Mr. Benedict Pagac, Entomologist, this Activity, was the project manager for this assessment. Assistance was provided in the field by: Dr. Howard Thomas, Department of Biology, Fitchburg State College, Fitchburg, Massachusetts; and Mr. Tom Poole, Wildlife Biologist, DEH, Fort Devens. 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 Lyme disease antibody. Ticks were identified and assayed via Direct Fluorescent Antibody (DFA) tests 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 (ESD), this Activity, Commercial Phone 410-677-5281/6502 or DSN 923-5281/6502. 5. METHODS. a. Tick Collection. The heads, ears, and necks of 4 shot white-tailed deer (Odocoileus virginianus) were examined immediately before or after the weighing and tagging process. Because the overall number of shot deer was low, additional time was spent looking for ticks on other regions of the deer carcasses. Total examination time-per-carcass was between 10 and 20 minutes. The hair was stroked contrary to the natural lay, using the hand edge, and ticks were removed from the exposed skin using fine-point (No. 5) jeweler's forceps. Collected ticks were placed in labeled, 20 ml humidified vials and kept cool (1.5 - 4.5 degrees C). b. Tick Testing. Ticks were assayed via Direct Fluorescent Antibody (DFA) testing using antibody conjugate from Kirkegaard and Perry Laboratories, Inc. to determine presence of the Lyme disease spirochete, B. burgdorferi. This conjugate is affinity absorbed to minimize cross reactivity with other spirochetes. c. Blood Samples. Blood pooled in the body cavities of 4 shot deer was collected using clean plastic (4 ml) disposable pipettes. Blood samples were not taken from carcasses that were rinsed with water or otherwise treated in a manner which might contaminate or invalidate the sample. Samples were placed in 7 ml labeled tubes, spun, sera were separated, and frozen (-9 degrees C) until Fluorescent Antibody testing could be performed. 6. RESULTS. (See also Enclosure 1) a. A total of 13 I. dammini ticks were collected from deer examined at Fort Devens. Two (50 percent) of the 4 deer examined, were infested with the deer tick I. dammini. Ten I. dammini ticks tested, were negative for the Lyme disease spirochete. b. None of the 4 serum samples tested from deer examined were positive (greater than 1:128 titer level) for Lyme disease antibodies. c. The Epidemiology Surveillance Program, Massachusetts Department of Public Health (MDPH), reports 37 confirmed human cases of Lyme disease in Middlesex County and 14 in Worcester County, in 1991. These are counties in which Fort Devens is located. There were 318 reported human cases statewide, in 1991. Most of the human Lyme disease cases in Massachusetts are reported from the eastern coastal counties. 7. DISCUSSION. This survey provides evidence that Lyme disease is established at Fort Devens. Although the small size of this survey did not reveal that the Lyme disease causing spirochete is established, the potential at-risk human population (e.g., military trainees, outdoor workers, and natural resources activity participants), availability of suitable vectors and animal hosts, environmental conditions necessary for the occurrence of Lyme disease, and past human Lyme disease in the nearby area, all make Fort Devens an area warranting continued vigilance. 8. CONCLUSIONS. The presence of specimens of I. dammini on examined deer, and information from the MDPH on the epidemiology of Lyme disease in Middlesex and Worcester Counties and surrounding areas, indicate that the present risk of contracting human Lyme disease at Fort Devens, is Moderate. 9. RECOMMENDATIONS. a. Implement contingency planning in accordance with guidelines in Enclosure 2. b. Conduct annual follow-up surveillance using the methods described in reference 1.b and para 5 above. [signature] BENEDICT B. PAGAC, JR. Entomologist Entomological Sciences Division APPROVED BY: [signature] JAMES T. KARDATZKE, PhD, BCE MAJ, MS Chief, Entomological Sciences Division Enclosure 1 DOD LYME DISEASE SURVEY U.S. ARMY ENVIRONMENTAL HYGIENE ACTIVITY-NORTH DATA SUMMARY - FALL/WINTER 1991 INSTALLATION Fort Devens, MA SURVEY DATE 2 December 1991 # OF DEER EXAMINED 4 # (%) DEER EXAMINED WITH Ixodes dammini 2 (50) # DEER SERUM SAMPLES TESTED 4 # DEER SERUM SAMPLES POSITIVE * 0 TICK SPECIMENS ----------------------------------- # COLLECTED # TESTED # POSITIVE Ixodes dammini ** 13 10 0 Dermacentor albipictus 0 0 0 Amblyomma americanum 0 0 0 --------------------------------- TOTAL TICKS 13 10 0 * positive screening titer levels greater than 1:128 ** Ixodes dammini vs. Ixodes scapularis determination in adult ticks is difficult. However, random samples of adult specimens from installations as far south as Virginia and North Carolina were all identified as I. dammini by The Curator of Ticks, U.S. National Tick Collection, at the Institute of Arthropodology and Parasitology at Georgia Southern University. Enclosure 2 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-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, the video LYME DISEASE: A growing threat (FAUPIN No. 504494DA). 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-North, FGGM, MD, 20755-5225. 3. Stock Permethrin Arthropod Repellent (NSN 6840-01-278-1336, 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 B. burgdorferi. Sampling should be performed in early summer when I. dammini nymphs (the life stage responsible for most human Lyme disease infections) are active. Post DA Poster 40-5 (or equivalent), and thereby 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. dammini. 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