Deployment and Travel Related Infections
U.S. military personnel deployed overseas in support of combat operations, humanitarian service, and training exercises, as well as military recruits at training facilities within the United States, are at risk of developing infectious diseases. Along with posing a threat to the health of service members and recruits, these infections also impact operational readiness and Force Health Protection.
Enhancing infectious disease preparedness of U.S. Armed Services prior to and during deployment for prevalent and re-emerging infectious disease threats (e.g., bacterial diarrhea, norovirus, and arboviruses) classified as priorities of the Military Health System (MHS) remains the core mission of the Deployment and Travel-Related Infections Research Area.
As acute diarrheal disease is common among deployed service members and has a considerable impact on operational readiness, a major focus of the research area is on clinical trials assessing interventions to mitigate travelers’ diarrhea (TD) and inform clinical practice guidelines (CPGs) for use in the deployed setting. Led by Dr. David Tribble, two clinical trials are underway, both in collaboration with the United Kingdom Ministry of Defense. As a continuation of the Trial Evaluating Ambulatory Therapy of TD (TrEAT TD) clinical trial, which demonstrated that a single high dose (1,650 mg) of rifaximin was effective for treating acute watery diarrhea, the TrEAT TD 2.0 clinical trial is assessing the efficacy of rifaximin at a lower dose (550 mg) for treating moderate/severe acute watery diarrhea compared to azithromycin (both with adjunct loperamide). The P2 clinical trial is a randomized placebo-controlled trial to assess the effectiveness of enterotoxigenic Escherichia coli passive immunoprophylaxis (Travelan®) for maintaining gut health of personnel during short travel or deployments (e.g., 10-20 days). Presently, enrollment is 50% completed for TrEAT TD 2.0 and 90% for P2. As enrollment for both clinical trials have been slower than expected due to cancellation of deployments or planned exercises and low TD rates in deployers, the enrollment periods have been extended. To bolster enrollment in TrEAT TD 2.0, expanding enrollment to include military exercises in the Indo-Pacific Command and Africa Command regions is being discussed.
Multiple surveillance studies are underway at overseas locations to examine the risk of emerging or re-emerging infectious disease threats and to further the understanding of how these infectious diseases affect the health of service members and operational readiness. Developed in collaboration with Preventive Medicine investigators of the III Marine Expeditionary Force, the Deployment Infection Threat Assessment and Outcomes Survey among U.S. Marines (MARSID) study is examining survey responses provided by U.S. Marines returning from military exercises in the Indo-Pacific Command region to estimate the incidence, trends, and operational impact of infectious diseases. During 2024, syndromic surveillance of U.S. Marines participating in an annual exercise with the Armed Forces of the Philippines (i.e., Balikatan Exercise) was completed. In addition, a new protocol, the Enhanced Infectious Disease Surveillance for U.S. Military Operations (MilOpsID) study, received USU Institutional Review Board approval and military exercises in different Combatant Command regions are being targeted for surveillance in 2025. The Leptospirosis in Jungle Warfare Training Environments (Leptospirosis JWT) study, which is being conducted to examine the military impact of leptospirosis in personnel undergoing jungle warfare training, enrolled >350 participants during the past year at training sites in Okinawa (Japan) and Hawaii. In collaboration with the Naval Medical Research Command, Hawaii Department of Health, and U.S. Army Public Health Command-Pacific, Camp Zama (Japan), paired sera and environmental samples are being assessed to identify pathogenic Leptospira species. Leptospirosis in high-risk deployed service members is also being examined through the Deployment and Travel-Related Infectious Disease Risk Assessment, Outcomes, and Prevention Strategies among DoD Beneficiaries (TravMil) study.
For the coming year, two new initiatives will address important gaps in Force Health Protection and inform consensus-driven, evidence-based CPGs. The first will address the lack of guidance related to use of culture-independent diagnostic platforms for TD by conducting a systematic review of assay performance characteristics, focusing primarily on the BioFire® Gastrointestinal Panel Assay, with the findings being used to design a prospective case-control study for use in operational settings. The second initiative will address the lack of effective Norovirus countermeasures by conducting a landscape review to develop a technical report identifying gaps and prioritizing potential countermeasures for review by a panel of subject-matter experts and DoD stakeholders. Enrollment and follow-up in the TrEAT TD 2.0 and P2 clinical trials will also be completed. For the MARSID study, as survey response rates during the Balikatan Exercise was low, investigators are working to improve awareness of MARSID and MilOpsID for future exercises.
Military Impact
Identifying effective interventions to mitigate TD and develop evidence-based CPGs are priority goals of the Research Area. If TrEAT TD 2.0 determines that a lower dose of rifaximin is effective at treating TD, those findings will inform an update of the DoD CPG for the management of acute watery diarrhea in the deployed setting. Likewise, if Travelan® is found to be effective at maintaining gut health of deployed personnel, these findings may also be used to support development of a DoD CPG for prevention of TD. Leptospirosis findings through the TravMil and Leptospirosis JWT studies will inform guidelines regarding chemoprophylaxis against leptospirosis in high-risk groups. Findings from MARSID are supporting infectious disease threat assessment reports for dissemination to unit leadership and Combatant Commands. Drs. Lalani and Tribble continue to serve on the GEIS Enterics Steering Committee, offering feedback on the GEIS Enterics Roadmap and proposals. Assessment of provider-knowledge and prescription practice patterns for pre-travel/deployment healthcare also continue to be a focus for the Research Area. Lastly, translational research efforts are evaluating culture-independent diagnostics for diarrheal pathogen detection and assessing the influence of travel, antibiotic use, and diarrheal disease on the gut microbiome and resistome.