A Multisite Network Assessment of the Epidemiology and Etiology of Acquired Diarrhea among U.S. Military and Western Travelers (Global Travelers’ Diarrhea Study): A Principal Role of Norovirus among Travelers with Gastrointestinal Illness

Abstract

The U.S. military personnel must be ready to deploy to locations worldwide, including environments with heightened risk of infectious disease. Diarrheal illnesses continue to be among the most significant infectious disease threats to operational capability. To better prevent, detect, and respond to infectious disease threats and improve synchronization across the Department of Defense (DoD) overseas laboratory network, a multisite Global Travelers' Diarrhea protocol was implemented with standardized case definitions and harmonized laboratory methods to identify enteric pathogens. Harmonized laboratory procedures for detection of Norovirus (NoV), enterotoxigenic Escherichia coli (ETEC), enteroaggregative E. coli, Shiga toxin-producing E. coli, enteropathogenic E. coli, Salmonella enterica, Shigella/ enteroinvasive E. coli, and Campylobacter jejuni have been implemented for six DoD laboratories with surveillance sites in Egypt, Honduras, Peru, Nepal, Thailand, and Kenya. Samples from individuals traveling from wealthy to poorer countries were collected between June 2012 and May 2018, and of samples with all variables of interest available (n = 410), most participants enrolled were students (46%), tourists (26%), U.S. military personnel (13%), or other unspecified travelers (11%). One or more pathogens were detected in 59% of samples tested. Of samples tested, the most commonly detected pathogens were NoV (24%), ETEC (16%), and C. jejuni (14%), suggesting that NoV plays a larger role in travelers' diarrhea than has previously been described. Harmonized data collection and methods will ensure identification and characterization of enteric pathogens are consistent across the DoD laboratory network, ultimately resulting in more comparable data for global assessments, preventive measures, and treatment recommendations.

Antimicrobial resistance of enteric pathogens in the Military Health System, 2009 – 2019

“…Also surprising was that SOUTHCOM presented no STEC samples and very few Shigella and Campylobacter cases -however their numbers overall were quite low. These differences might reflect variations in sample collection practices or capabilities in deployed settings [19,31], or may be due to a reluctance of patients to provide stool samples.…”

Travel‐related gastrointestinal diseases: Assessment and management

“…In recent years, enteroaggregative E. coli has become more frequently identified in the stools of patients with TD, with some studies finding higher rates of enteroaggregative E. coli than enterotoxigenic E. coli in patients from Africa [36] and Latin America [37]. Enteroaggregative E. coli has been found in 7%-54% [38,39] of stool samples of patients with TD, while enteropathogenic E. coli has been identified in 8%-44% [38,39]. Nevertheless, there is ambiguity about the pathogenicity of enteroaggregative E. coli and enteropathogenic E. coli, as they have a high prevalence in asymptomatic travellers [40].…”

“…Viral pathogens associated with TD include norovirus and rotavirus. Norovirus in particular seems to have increased its frequency relative to other aetiologic agents in recent years and in some studies has been the most commonly identified pathogen [34,38]. There is also some uncertainty regarding the pathogenic significance of norovirus, given the identification of high amounts of viral shedding in asymptomatic paediatric patients [47].…”

Novel rpsK / rpsD primer-probe assay improves detection of Campylobacter jejuni and Campylobacter coli in human stool

“…Campylobacter has been classified as a leading cause of bacterial gastroenteritis and growth stunting in children living in poverty. Campylobacter jejuni and Campylobacter coli are the predominant Campylobacter species associated with gastroenteritis, both in pediatric populations and in cases of travellers' diarrhea [1][2][3]. Additionally, C. jejuni, C. coli and other Campylobacter spp.…”