Objectives

The aim of this study was to assess the risk of incident rheumatological diagnoses (RD) associated with self-reported diarrhoea and vomiting during a first-time deployment to Iraq or Afghanistan. Such an association would provide evidence that RD in this population may include individuals with reactive arthritis (ReA) from deployment-related infectious gastroenteritis.

Design

This case-control epidemiological study used univariate and multivariate logistic regression to compare the odds of self-reported diarrhoea/vomiting among deployed US military personnel with incident RD to the odds of diarrhoea/vomiting among a control population.

Setting

We analysed health records of personnel deployed to Iraq or Afghanistan, including responses on a postdeployment health assessment and medical follow-up postdeployment.

Participants

Anonymous data were obtained from 891 US military personnel with at least 6 months of medical follow-up following a first-time deployment to Iraq or Afghanistan in 2008-2009. Cases were defined using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes; controls had an unrelated medical encounter and were representative of the study population.

Main outcome measures

The primary measure was an association between incident RD and self-reported diarrhoea/vomiting during deployment. A secondary measure was the overall incidence of RD in this population.

Results

We identified 98 cases of new onset RD, with a total incidence of 161/100 000 persons. Of those, two participants had been diagnosed with Reiter's disease (i) (3.3/100 000 persons) and the remainder with non-specific arthritis/arthralgia (157.5/100 000 persons). The OR for acute diarrhoea was 2.67 (p=0.03) after adjusting for important covariates.

Conclusions

Incident rheumatological conditions, even those classified as 'non-specific,' are significantly associated with prior severe diarrhoea in previously deployed military personnel, potentially indicating ReA and need for preventive measures to reduce diarrhoeagenic bacterial exposures in military personnel and other travellers to the developing regions.

Background

The US CDC estimates over 2 million foodborne illnesses are annually caused by 4 major enteropathogens: non-typhoid Salmonella spp., Campylobacter spp., Shigella spp. and Yersinia enterocoltica. While data suggest a number of costly and morbid chronic sequelae associated with these infections, pathogen-specific risk estimates are lacking. We utilized a US Department of Defense medical encounter database to evaluate the risk of several gastrointestinal disorders following select foodborne infections.

Methods

We identified subjects with acute gastroenteritis between 1998 to 2009 attributed to Salmonella (nontyphoidal) spp., Shigella spp., Campylobacter spp. or Yersinia enterocolitica and matched each with up to 4 unexposed subjects. Medical history was analyzed for the duration of military service time (or a minimum of 1 year) to assess for incident chronic gastrointestinal disorders. Relative risks were calculated using modified Poisson regression while controlling for the effect of covariates.

Results

A total of 1,753 pathogen-specific gastroenteritis cases (Campylobacter: 738, Salmonella: 624, Shigella: 376, Yersinia: 17) were identified and followed for a median of 3.8 years. The incidence (per 100,000 person-years) of PI sequelae among exposed was as follows: irritable bowel syndrome (IBS), 3.0; dyspepsia, 1.8; constipation, 3.9; gastroesophageal reflux disease (GERD), 9.7. In multivariate analyses, we found pathogen-specific increased risk of IBS, dyspepsia, constipation and GERD.

Conclusions

These data confirm previous studies demonstrating risk of chronic gastrointestinal sequelae following bacterial enteric infections and highlight additional preventable burden of disease which may inform better food security policies and practices, and prompt further research into pathogenic mechanisms.