Deployment and Travel Related Infections
Whether traveling overseas in support of combat operations, humanitarian service, or training exercises, U.S. military personnel are at risk of developing infectious diseases. Outbreaks are also common among military recruits at training facilities within the United States. These infections affect the health of service members and recruits, as well as impact operational readiness and Force Health Protection.
Identifying effective interventions to mitigate the impact of infectious diseases (e.g., bacterial diarrhea, norovirus, and vector-borne pathogens) that threaten military operational readiness remain the core of the Deployment and Travel-Related Infections Research Area. Central to the research portfolio are clinical trials examining strategies to reduce the impact of travelers’ diarrhea (TD) on deployed service members and mission readiness. A previously completed clinical trial, the Trial Evaluating Ambulatory Therapy of TD (TrEAT TD), showed that a single high dose (1,650 mg) of rifaximin was effective for treating acute watery diarrhea. Led by Dr. David Tribble, and in collaboration with the United Kingdom Ministry of Defence (U.K. MOD), the objective of the TrEAT TD 2.0 clinical trial is to evaluate the efficacy of a lower dose (550 mg) of rifaximin for treating moderate/severe acute watery diarrhea compared to azithromycin (adjunct loperamide with both groups). Also, in collaboration with the U.K. MOD and across several U.S. military sites, the P2 randomized placebo-controlled clinical trial, led by Dr. Tahaniyat Lalani, is examining the effectiveness of enterotoxigenic Escherichia coli (ETEC) hyperimmune bovine colostrum passive immunoprophylaxis (active ingredient in Travelan®) to support service members in maintaining gut health and reducing TD or ETEC-associated TD during short travel or deployments (e.g., 10-20 days). Enrollment and follow-up have been completed for both clinical trials and data analysis is underway.
Norovirus is also a substantial threat to operational readiness in military shipboard environments. During the past year, the IDCRP hosted a Countermeasures to Defeat Norovirus Symposium attended by experts from military and public health institutes and academia. Based on a landscape review and gap analysis related to norovirus mitigation strategies, the convened experts prioritized interventions that have the potential to reduce the impact of norovirus in military settings for evaluation in prospective studies or clinical trials.
Surveillance studies are another focus of the research area and are collecting data on emerging or re-emerging infectious disease threats overseas. The Enhanced Infectious Disease Surveillance for U.S. Military Operations (MilOpSID) study is a new protocol led by COL Kevin Taylor set to start in 2026. During the past year, COL Taylor briefed Combatant Commands and engaged with military exercise planners to gather support for the study. Another protocol, the Leptospirosis in Jungle Warfare Training Environments (Leptospirosis JWT) study led by USU Professor Kyle Petersen, based at the Marine Corps training site in Okinawa and the Army site in Hawaii, completed participant enrollment and follow-up in 2025 with data analysis ongoing.
Examination of post-infectious sequelae after diarrheal episodes are the objective of the Gut Microbiome and Guillain-Barré Syndrome (GBS) and Tripler Army Medical Center (TAMC) Diarrhea Case Cohort studies led by Dr. Tribble. The first study evaluates associations between antecedent Campylobacter serology and GBS development, while the second is assessing outcomes using abstracted medical record data from diarrheal cases based on pathogens (i.e., Campylobacter spp., pathogens other than Campylobacter spp., or no growth on stool culture). Additionally, in collaboration with investigators at the Armed Forces Research Institute of Medicine and Naval Medical Research Command, genotype and phenotype analysis of Campylobacter isolates and host immunologic responses will be examined to inform Campylobacter vaccine candidates.
In the forthcoming year, a new prospective TD Case-Control Study, led by Dr. Lalani, will be initiated in collaboration with overseas military research labs and the U.K. MOD to evaluate the clinical performance characteristics of the BioFire® FilmArray® Gastrointestinal (GI) Panel in operational environments, as well as to assess the impact of antimicrobial resistance on treatment outcomes. Data analysis for the TrEAT TD 2.0 and P2 clinical trials will be completed, and findings will be provided to the Defense Health Agency (DHA) Military Infectious Diseases (MID). Starting in the Spring of 2026, infectious disease surveillance through MilOpSID will be conducted among active-duty service members participating in exercises and deployments across various Combat Commands. Laboratory and data analysis for the Leptospirosis JWT, GBS, and TAMC Diarrhea Case Cohort studies will also be completed.
Military Impact
Supporting Force Health Protection and operational readiness through identifying effective infectious disease mitigation strategies and informing evidence-based recommendations are priorities of the research area. Findings from the Treat TD 2.0 and P2 clinical trials will inform deployment-related clinical practice guidelines, support use of field expedient diagnostics to determine pathogen-specific TD epidemiology and provide evidence on the impact of gut dysbiosis on clinical outcomes. Discussions are underway with DHA MID regarding how lessons learned from both the TrEAT TD 2.0 and P2 clinicals trials can be used to develop a framework for an adaptive clinical trial focused on evaluating the effectiveness of passive immunoprophylaxis products against TD. Furthermore, although effective treatment strategies and robust public health measures to combat TD often rely on accurate and timely etiological diagnosis, standardized guidelines for interpreting these results in operational settings are lacking. Findings from the TD Case Control will support the generation of consensus-driven, evidence-based clinical and public health guidelines for the appropriate use and interpretation of the BioFire® FilmArray® GI Panel in TD management. Feedback from experts during the Countermeasures to Defeat Norovirus Symposium provide support for a clinical trial to evaluate a bundled norovirus mitigation strategy with the aim of reducing acute gastroenteritis in military shipboard settings, decreasing the number of duty days lost, and improving the speed of outbreak responses. If proven effective, the mitigation approach could inform Navy-wide norovirus policies and be adapted to other operational settings. Data from MilOpSID will inform infectious disease threat assessment and disease non-battle injury reports for Combatant Commands. Reports from other surveillance studies on the occurrence of leptospirosis, diarrheal disease outcomes, and deployment-related infectious disease risks will inform military health strategies in operational settings. Lastly, Dr. Lalani continues to serve on the GEIS Enterics Steering Committee, offering feedback on the GEIS Enterics Roadmap and proposals.