US Air Force Report- 2000- 2011
Reported Vectorborne and Zoonotic Diseases, U.S. Air Force, 2000-2011
Madeline M. Anna, BS; James D. Escobar, MPH; Alice S. Chapman, DVM, MPH (Col, U.S. Air Force)
During 2000-2011, U.S. Air Force Public Health Officers reported 770 cases of vectorborne and zoonotic diseases diagnosed at Air Force medical treatment facilities. Cases of Lyme disease accounted for 70 percent (n=538) of all cases and most cases of Lyme disease (57%) were reported from bases in the northeastern U.S. and in Germany. The annual numbers of reported Lyme disease cases were much higher during the last four years than earlier in the surveillance period. The next most commonly reported events were malaria (74 cases), Rocky Mountain spotted fever (RMSF) (41), Q fever (33), dengue (23), and leishmaniasis (20). These five infections and Lyme disease accounted for 95 percent of the reported conditions. Military service members accounted for a majority of the reported cases for most of the conditions, but family members and retirees accounted for most of the cases of Lyme disease and RMSF. Most reports of vectorborne and zoonotic diseases did not include mentions of recent travel.
u.S. Air Force members are exposed to potential disease vec- tors where they live, train, and deploy throughout the world. Similarly, military family members living and trav- eling in endemic areas are also at risk for vectorborne diseases. Arthropods includ- ing mosquitoes, ticks, mites, and sand flies make up the greatest proportion of vectors that transmit diseases of military significance.1 Zoonotic diseases transmit- ted from animals to humans are less fre- quently reported in military settings but also have the potential to cause severe ill- ness or death. Air Force Public Health personnel at each base monitor the occur- rence of vectorborne and zoonotic diseases specified in the Armed Forces (formerly Tri-Service) Reportable Events Guidelines & Case Definitions and submit electronic reports of incident cases through the Air Force Reportable Events Surveillance Sys- tem (AFRESS) to the Epidemiology Con- sult Service at the U.S. Air Force School of Aerospace Medicine.2
Historically, the Epidemiology Con- sult Service has compiled summaries of the annual incidence rates for certain report- able events (e.g., sexually transmitted and gastrointestinal infections). These rates are tabulated and analyzed according to major command and installation and are available
to those with access to the Epidemiology Consult Service website. This report sum- marizes information on the incidence of the vectorborne and zoonotic diseases most frequently reported through AFRESS, and the demographic characteristics, travel pat- terns, and geographic distribution of cases. Opportunities for prevention and control are discussed in light of these findings.
The surveillance period was 1 January 2000 through 31 December 2011. AFRESS was queried for reported events with ICD-9 codes corresponding to anthrax, brucellosis, arboviral encephalitis, dengue, ehrlichiosis/anaplasmosis, filariasis, hanta- virus, hemorrhagic fever, leishmaniasis (all types), leprosy, leptospirosis, Lyme disease, malaria (all types), plague, Q fever, relaps- ing fever, Rift Valley fever, Rocky Mountain spotted fever (RMSF), trypanosomiasis, tularemia, and typhus. The population of interest consisted of recipients of health care at Air Force medical treatment facili- ties (MTFs) during the surveillance period. Beneficiaries of such care were grouped into four categories: military members (including active and reserve compo- nent members), retired service members,
dependents (i.e., family members), and others. By using dates of onset and infor- mation in the comment fields of AFRESS reports, duplicate records were removed, as were cases for which a vectorborne or zoo- notic disease was ultimately ruled out. Rel- evant travel histories (as reported through AFRESS) were defined by exposures to locations within 60 days preceding disease onsets; up to three locations could be con- sidered potentially relevant exposures for each reported case. For surveillance pur- poses, countries were grouped by major command. Data were analyzed using SAS 9.2 (SAS Institute Inc., Cary, NC).
During the 12-year surveillance period, 770 cases of vectorborne and zoo- notic disease were reported among benefi- ciaries receiving care at Air Force medical treatment facilities. Ten bases accounted for more than half (51.4%) of all case events: McGuire AFB, NJ (100); Ramstein AB, Germany (91); Andrews AFB, MD (47); Spangdahlem AB, Germany (35); Hanscom AFB, MA (29); Dover AFB, DE (25); Scott AFB, IL (20); Tinker AFB, OK (17); Bolling AFB, DC; and MacDill AFB, FL (16 cases each). Nearly half (357, 46%) of the cases had their onsets during the months of June, July, or August. In total, 725 (94%) of the reported cases were recorded in AFRESS as having been confirmed in accordance with the Tri-Service Reportable Events Guidelines in effect at the time of disease onset. The most common confirmation methods were serology and clinical diagnosis, account- ing for 561 confirmed cases (77%). Other categories of confirmation included cul- ture (59); blood smear (30); or biopsy (18). The method of confirmation was not stated for 57 cases. Table 1 summarizes the demo- graphic characteristics of all reported cases.
Lyme disease accounted for 70 percent (n=538 cases) of all reported vectorborne or zoonotic diseases during the period. There were more cases of Lyme disease
October2012 Vol.19 No.10 MSMR
T A B L E 2 . Cases of vectorborne and zoonotic diseases reported by Air Force medical treatment facilities, by beneficiary category, 2000-2011
Encephalitis, arboviral/ tickborne
Leprosy Hantavirus Leptospirosis Tularemia Relapsing fever Trypanosomiasis Plague
538 232 74 66 41 16 33 21 23 16 20 18
7 3 7 5
6 2 4 2 3 2 3 2 2 1 2 1 1 .
43 257 89 4 39 19 64 6 70 4 90 . 43 1 71 2
33 3 50 1 67 1 67 1 50 . 50 1
. 1 . 303
48 46 5 1 46 6 18 3 17 3 . 1 14 1 29 .
50 1 25 1 33 . 33 .
. 1 50 . 100 . . 65
9 3 1
1 3 4 15 . . 9 3 9 13 . . 5 1 5 14 2 29 . . .
17 . .
17 . . 25 . . . . . . . . 50 . . . . . . . . . 12 .
Total 770 390
T A B L E 1 . Reported cases of vectorborne or zoonotic diseases, by military and demographic characteristics, Air Force Reportable Events Surveillance System, 2000-2011
<1-17 164 21.3 18-24 99 12.9 25-34 189 24.5 35-44 176 22.9 45-64 124 16.1 65+ 18 2.3
Male 443 57.6 Female 296 38.4 Not reported 31 4.0
Military 390 50.6 Dependent 303 39.4 Retiree 65 8.4 Other 12 1.6
Air Force 628 81.7 Army 86 11.2 Navy 29 3.8 Marine Corps 12 1.6 Othera 15 1.9
a1 unknown, 1 Coast Guard and 13 civilians (non-service affiliated)
FIGURE 1. Cases of vectorborne and zoonotic diseases reported through the
among family members (257 cases, 48%) than military members (232 cases, 43%). Most (284, 53%) Lyme disease cases were confirmed by serology; 133 (25%) were diagnosed clinically. Bases in the north- eastern U.S. (McGuire, Andrews, Hans- com, and Dover) and Germany (Ramstein and Spangdahlem) accounted for 57 per- cent of the reported cases of Lyme disease. Lyme disease reports sharply increased from 2006 (n=25) through 2008 (n=79); there were many more cases each year from 2008-2011 than during any previous year of the period (Figure 1).
The next most commonly reported events were malaria (74 cases), RMSF (41), Q fever (33), dengue (23), and leishmani- asis (20). Together with Lyme disease, these accounted for 95 percent of all reported cases of vectorborne and zoonotic diseases. In contrast to Lyme disease and RMSF, cases of malaria, Q fever, dengue, and leish- maniasis were reported predominantly among active military members (121 of 150 total reports of these four conditions). Table 2 summarizes the military health care beneficiary statuses of all individu- als affected by vectorborne and zoonotic
diseases (as reported through AFRESS) during the surveillance period.
Travel or deployments within 60 days preceding disease onsets were documented in AFRESS for 238 (31%) of all the report- able events addressed in this report. Cases reported travel to 70 different countries, and 48 (20%) of recently traveled cases vis- ited two or more countries. Of note, 91 per- cent of reported travel among Lyme disease cases was to the U.S. European Command (EUCOM) region, predominantly Ger- many, and to the U.S. Northern Command (NORTHCOM), primarily the northeast- ern U.S. For the majority of cases (532, 69%), no travel beyond the local residence area was recorded. Table 3 summarizes the locations of travel by geographic command reported by patients diagnosed with vec- torborne and zoonotic diseases.
This report summarizes cases of vec- torborne and zoonotic diseases (reported through the AFRESS) among Department of Defense (DoD) beneficiaries who received
Air Force Reportable Events Surveillance System (AFRESS), 2000-2011
140 120 100
80 60 40 20
All other reportable diseases
Year of onset
MSMR Vol.19 No.10 October2012
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011
T A B L E 3 . Cases of vectorborne and zoonotic diseases and number of trips to combatant command (COCOM) locations reported by cases, Air Force Reportable Events Surveillance System, 2000-2011
79.7 21.6 90.2 45.5 13.0
109 20.3 58 78.4 4 9.8 18 54.5 20 87.0 19 95.0 10 24.4
40 27.7 1 4 5.3 12 4 100.0 0 1 6.0 1 4 15.4 4 0 0.0 0 6 60.0 2
0.7 16.0 0.0 5.0 15.4 0.0 20.0
1 0.7 29 38.7 0 0.0 3 15.0 2 7.7 0 0.0 0 0.0
91 63.2 3 4.0 0 0.0 0 0.0 1 3.8 1 4.0 0 0.0
5 3.5 21 28.0 0 0.0 15 75.0 0 0.0 23 92.0 1 10.0
6 4.2 6 8.0 0 0.0 0 0.0
15 57.7 1 4.0 1 10.0
538 429 74 16 41 37 33 15 23 3 20 1 41 31
aTravel or deployment within 60 days prior to disease onset documented in AFRESS
bBrucellosis, erlichiosis/anaplasmosis, encephalitis (arborviral/tickborne), leprosy, hantavirus, leptospirosis, tularemia, relapsing fever, trypanosomiasis, and plague cTravel or deployment reported by cases. Because cases could report up to three travel locations, total number of trips may exceed the number of cases.
care at Air Force medical treatment facili- ties from 2000-2011. Lyme disease cases constituted the largest proportion of over- all reportable events. The predominance of reporting from bases located in the north- eastern U.S. and Germany coincides with the regions where Lyme disease is known to be endemic.3-6 Only a small proportion of Lyme disease cases included any docu- mentation of travel away from the home station area, suggesting that the majority of the illnesses were acquired locally. In con- trast, diseases not endemic to the U.S. and Europe, such as malaria, leishmaniasis, and dengue, occurred much more frequently among active military members than fam- ily members or other health care beneficia- ries and were most often associated with foreign travel.
Most of the reports of vectorborne and zoonotic diseases did not include mentions of recent travel. Whether such reports accurately depict recent travel as a risk fac- tor or reflect a limitation in obtaining com- prehensive travel histories is uncertain. However, unreported travel is less likely to be a factor in Lyme disease cases, most of which were reported from highly endemic areas. Reports of travel were more com- monly reported among cases of malaria, leishmaniasis, dengue, and Q fever.
Between 2000 and 2007, vectorborne and zoonotic diseases were reported in rela- tively low numbers and varied considerably
from year to year. The observed reporting pattern is not due to changes in clinical and laboratory criteria for reporting these conditions; the criteria were unchanged between 1998 and 2004, when Tri-Ser- vice Reportable Events Guidelines were updated.7,8 More likely, the pattern reflects medical treatment facility-specific surveil- lance procedures that tended to focus on more frequently occurring events such as sexually-transmitted and gastrointestinal illnesses. The increase in reported inci- dence since 2008 is likely due to several factors. The increase in vectorborne and zoonotic diseases other than Lyme disease (i.e., malaria, leishmaniasis, dengue, and Q fever) coincides with increased U.S. mili- tary deployments to the CENTCOM and AFRICOM areas of responsibility where these diseases are prevalent. Increased reporting of Lyme disease among DoD ben- eficiaries parallels a similar trend in Lyme disease incidence reported by the Centers for Disease Control and Prevention for the same period.4 Public health education cam- paigns such as those initiated by the Cen- ters for Disease Control and Prevention have resulted in increased awareness by the public, who may be more likely to report tick bites, and by physicians, who are more apt to recognize clinical signs and to test for Lyme disease.
The findings of this report have impli- cations for prevention and control of
vectorborne and zoonotic diseases among DoD beneficiaries. Historically, the mili- tary’s efforts to control vectorborne diseases have focused on the use of permethrin- treated uniforms, DEET-containing insect repellent on exposed skin, proper uniform wear, and where indicated, prophylactic medications. These measures have been in use from World War II through the recent conflicts in Iraq and Afghanistan to reduce the impacts of arthropod-borne diseases on military operations. Despite the avail- ability of highly effective countermeasures, however, vectorborne diseases continue to reduce military operational capabilities.9
The diverse reservoirs and modes of transmission associated with the zoonoses of interest for this report suggest the need for a variety of prevention tools and strate- gies. It is notable that 59 percent of the vec- torborne and zoonotic illnesses reported among military members and 81 percent of such illnesses among other military health care beneficiaries were due to Lyme dis- ease, the majority of which occurred at or near home station. While some of these events among military members may have been related to military training conducted outdoors in tick-infested areas, it is likely that many were the result of exposures dur- ing off-duty pursuits (e.g., hiking, camping, and gardening).
The findings of this report under- score the need for increased education and
October2012 Vol.19 No.10 MSMR
prevention efforts aimed at military mem- bers as well as family members and retirees; such efforts should be tailored to recreational activities that increase risk of exposures to known vectors of zoonotic infectious dis- eases. For example, some of the zoonotic diseases reported here may have involved contact with animals (domestic and wild) during on and off-duty activities; partici- pants in such activities should be reminded to avoid contact with animal body fluids/ feces. Targeted public health messages, aimed at the right audiences with the right content at the right time, may prove more effective in reducing the risk of vectorborne and zoonotic diseases than one-size-fits-all approaches.
Author affiliations: United States Air Force School of Aerospace Medicine, Department of Public Health and Preventive Medicine, Epidemiology Consult Service, Wright-Pat- terson Air Force Base, Ohio (Ms. Anna, Mr. Escobar, Dr. Chapman).
1. Armed Forces Pest Management Board. Personal protective measures against insects and other arthropods of military significance. Washington, DC: Armed Forces Pest Management Board; October 2009. Technical Guide No. 36.
2. Armed Forces Health Surveillance Center. Armed Forces Reportable Medical Events Guidelines & Case Definitions. March 2012. Available at http://www.afhsc.mil/ viewDocument?file=TriService_CaseDefDocs/
3. Steere AC, Coburn J, Glickstein L. The emergence of Lyme disease. J Clin Invest 2004;113(8):1093-1101.
4. Centers for Disease Control and Prevention. Lyme disease data. Available at http://www.cdc. gov/lyme/stats/index.html. Accessed 26 July 2012.
5. Bacon RM, Kugeler KJ, Mead PS, et al. Surveillance for Lyme disease-United States, 1992-2006. MMWR Surveill Summ 2008;57(10): 1-9.
6. Rizzoli A, Hauffe HC, Carpi G, et al. Lyme borreliosis in Europe. Euro Surveill 2011;16(27):1-8.
7. Army Medical Surveillance Activity. Tri-service reportable events guidelines & case definitions. Version 1.0. Washington, DC. July 1998:55-56. 8. Army Medical Surveillance Activity. Tri-service reportable events guidelines & case definitions. Washington, DC. May 2004:58-59.
9. Sanders, JW, Putnam SD, Frankart C, et al. Impact of illness and non-combat injury during Operations Iraqi Freedom and Enduring Freedom (Afghanistan). Am J Trop Med Hyg 2005;73(4):713-719.