Travelers’ diarrhea: Modern concepts and new developments

Enteric etiological surveillance in acute diarrhea stool of United States Military Personnel on deployment in Thailand, 2013-2017

Background

Diarrhea remains a major public health problem for both civilian and military populations. This study describes the prevalence of acute diarrheal illness etiological agents, their antibiotic resistance distribution patterns, the resulting impact upon military force health protection, and potential prevention and treatment strategies.

Results

Forty-eight acute diarrhea stool samples from US military personnel deployed to Thailand from 2013–2017 were screened for enteric pathogens using ELISA, the TaqMan Array Card (TAC), and conventional microbiological methods. These isolates were also evaluated using antimicrobial susceptibility testing (AST) against ampicillin (AMP), azithromycin (AZM), ceftriaxone (CRO), ciprofloxacin (CIP), nalidixic acid (NA), erythromycin (ERY), and trimethoprim-sulfamethoxazole (SXT) using commercial methodology. Susceptibility results were interpreted following the CLSI and NARM guidelines. Questionnaire data obtained from 47/48 volunteers indicated that 89.4% (42/47) reported eating local food and the most common clinical symptoms were nausea and abdominal pain (51%; 24/47). Multiple bacterial species were identified from the 48 stool samples with diarrhea etiological agents being detected in 79% (38/48) of the samples distributed as follows: 43.8% (21/48) Campylobacter jejuni and Campylobacter species, 42% (20/48) diarrheagenic Escherichia coli, and 23% (11/48) Salmonella. Co-infections were detected in 46% (22/48) of the samples. All C. jejuni isolates were resistant to CIP and NA. One C. jejuni isolate exhibited resistance to both AZM and ERY. Lastly, an association between exposure to poultry and subsequent detection of the diarrhea-associated pathogens E. coli and P. shigelloides was significant (p < 0.05).

Conclusion

The detection of Campylobacter isolates with CIP, AZM and ERY resistance has critical force health protection and public health implications, as these data should guide effective Campylobacteriosis treatment options for deployed military members and travelers to Southeast Asia. Additional research efforts are recommended to determine the association of pathogen co-infections and/or other contributing factors towards diarrheal disease in military and traveler populations. Ongoing surveillance and AST profiling of potential disease-causing bacteria is required for effective disease prevention efforts and treatment strategies.

Risk of functional gastrointestinal disorders in U.S. military following self-reported diarrhea and vomiting during deployment

INTRODUCTION

Military personnel are frequently deployed to regions of the world with high travelers' diarrhea (TD) rates. Pathogens associated with TD have been linked to several post-infectious sequelae, including functional gastrointestinal disorders (FGD), such as irritable bowel syndrome (IBS) and functional dyspepsia. Furthermore, stress associated with deployment may potentiate the increased FGD risk.

AIM

We sought to assess whether self-reported diarrhea, vomiting, and stressors during deployment were associated with increased FGD risk.

METHODS

Using active duty military medical encounter data from the Defense Medical Surveillance System (DMSS), we conducted a matched case-control study to assess the odds of FGD (IBS, functional constipation, functional diarrhea, dyspepsia) following self-reported diarrhea or vomiting during deployment. Only first-time deployers with detailed self-reporting of deployment-related exposures from 2008 and 2009 were included. Univariate and multivariate analyses were performed.

RESULTS

A total of 129 cases of FGD were identified, with the following distribution: constipation (n = 67), dyspepsia (n = 15), IBS (n = 22), and overlapping disorders (n = 25). Diarrhea and/or vomiting during deployment were significantly associated with the development of FGD. Other demographic factors were also associated with variable risk. We found no consistent effect of war-related stressors or non-combat-related correlates of stress.

CONCLUSIONS

Deployment-related TD is common in deployed military personnel and is associated with an increased risk of several FGD. When considering effective countermeasures and mitigation strategies, both the acute effects and chronic sequelae of enteric infections should be considered. Increased emphasis on existing and novel primary prevention strategies are needed, as well as outcome studies among those developing these conditions.

Prevention of travelers' diarrhea with rifaximin in US travelers to Mexico

BACKGROUND

Because bacterial pathogens are the primary cause of travelers' diarrhea (TD), antibiotic prophylaxis is effective in TD prevention. This study assessed the efficacy and safety of the nonsystemic antibiotic rifaximin in preventing TD in US travelers to Mexico.

METHODS

Healthy adult students traveling to Mexico received rifaximin 600 mg/d or placebo for 14 days and were followed for 7 days post-treatment. Stool pattern and gastrointestinal symptoms were recorded in daily diary entries. The primary end point was prevention of TD during 14 days of treatment measured by time to first unformed stool.

RESULTS

A total of 210 individuals received rifaximin (n = 106) or placebo (n = 104) and were included in the safety population. Median age was 21 years (range, 18-75 y), and the majority of participants were female (65%). Efficacy analyses were conducted in a modified intent-to-treat population of 201 patients who received rifaximin (n = 99) or placebo (n = 102). Rifaximin prophylaxis reduced risk of developing TD versus placebo (p < 0.0001). A smaller percentage of individuals who received rifaximin versus placebo developed all-cause TD (20% vs 48%, respectively; p < 0.0001) or TD requiring antibiotic therapy (14% vs 32%, respectively; p = 0.003). More individuals in the rifaximin group (76%) completed treatment without developing TD versus those in the placebo group (51%; p = 0.0004). Rifaximin provided a 58% protection rate against TD and was associated with fewer adverse events than placebo.

CONCLUSIONS

Prophylactic treatment with rifaximin 600 mg/d for 14 days safely and effectively reduced the risk of developing TD in US travelers to Mexico. Rifaximin chemoprevention should be considered for TD in appropriate individuals traveling to high-risk regions.

Travelers' preferences for the treatment and prevention of acute diarrhea

BACKGROUND

A survey was designed to assess travelers' willingness to take antibiotic chemoprophylaxis against travelers' diarrhea (TD) or to intervene with antibiotic or symptomatic treatments.

METHODS

A brief written questionnaire was administered to clients in North American (United States and Canadian) and European (UK and German) travel clinic waiting rooms to assess length, purpose, and destination of their upcoming trips; their perceived risk of developing TD at their destination; and their preferences for hypothetical treatment or chemoprophylaxis options, which included descriptions, but no mention of brand names, of a systemically absorbed antibiotic based on a fluoroquinolone, a nonabsorbed antibiotic based on rifaximin, and an over-the-counter antidiarrheal similar to loperamide.

RESULTS

The 209 UK and German travelers planned significantly longer travel than the 277 US and Canadian travelers (25 vs 15 d, p < 0.001) and correctly recognized high risk of TD more often than the North Americans (81% vs 61%, p < 0.001). More of the North Americans preferred any therapy options compared with the Europeans; only 14% of the North Americans preferred no treatment compared with 29% of the Europeans (p < 0.001). More of the North Americans and the Europeans preferred the nonabsorbed antibiotic than the systemically absorbed antibiotic, regardless of if combined with the antidiarrheal agent. Significantly more of the Europeans preferred not to take antibiotic chemoprophylaxis than North Americans (66% vs 37%, p < 0.001). Among the North Americans, significantly more travelers preferred chemoprophylaxis with the nonabsorbed than the systemic antibiotic (45% vs 33%, p= 0.003).

CONCLUSIONS

Among the relatively small groups of travelers studied, the UK and German travelers were more cognizant of TD risk than US and Canadian travelers. The Europeans were less inclined to take chemoprophylaxis or treatment. Both groups preferred treatment or prophylaxis with the nonabsorbed antibiotic over the systemically absorbed antibiotic or the antidiarrheal agent.

Clostridium difficile-associated diarrhea after antibiotic treatment for traveler's diarrhea

Diarrhea commonly affects international travelers. Episodes are usually short-lasting, but in some patients, symptoms may persist. Clostridium difficile infection should be excluded in travelers with prolonged disease. We report what is, to our knowledge, the first reported study of patients with C. difficile-associated diarrhea after receipt of antibiotic treatment for traveler's diarrhea.

Postinfectious irritable bowel syndrome

After acute bacterial gastroenteritis, up to one-third of patients will have prolonged gastrointestinal complaints, and a portion of those affected will meet the diagnostic criteria for postinfectious irritable bowel syndrome. After resolution of the acute infection, patients with postinfectious irritable bowel syndrome appear to have chronic mucosal immunologic dysregulation with altered intestinal permeability and motility that can lead to persistent intestinal symptoms. Both host- and pathogen-related factors, such as preexisting psychological disorders and duration of initial infection, have been associated with an increased risk for the development of postinfectious irritable bowel syndrome. Current treatments for postinfectious irritable bowel syndrome are typically targeted at specific symptoms, although studies evaluating therapies directed at preventing or reducing the duration of the initial infection are ongoing.

Treatment of travelers' diarrhea: randomized trial comparing rifaximin, rifaximin plus loperamide, and loperamide alone

BACKGROUND & AIMS

Antimotility agents provide rapid temporary relief of acute diarrhea, whereas antibiotics slowly cure the illness. Thus, the combination of an antimotility agent and an antibiotic may provide greater therapeutic benefit than either drug alone. This study evaluated the efficacy and safety of rifaximin-loperamide in the treatment of travelers' diarrhea.

METHODS

Consenting adults with acute diarrhea (> or =3 unformed stools in 24 hours with > or =1 symptom of enteric infection) were randomized to receive rifaximin 200 mg 3 times daily for 3 days; loperamide 4 mg initially followed by 2 mg after each unformed stool; or a combination of both drugs using the same dosing regimen. The primary end point was the median time from beginning therapy until passing the last unformed stool.

RESULTS

A total of 310 patients completed treatment with rifaximin (n = 102), loperamide (n = 104), or rifaximin-loperamide combination therapy (n = 104). The groups showed demographic similarity. Rifaximin and rifaximin-loperamide significantly reduced the median time until passage of the last unformed stool (32.5 +/- 4.14 h and 27.3 +/- 4.13 h, respectively) vs loperamide (69 +/- 4.11 h; P = .0019). The mean number of unformed stools passed during illness was lower with rifaximin-loperamide (3.99 +/- 4.28) compared with rifaximin (6.23 +/- 6.90; P = .004) or loperamide alone (6.72 +/- 6.93; P = .002). All treatments were well tolerated with a low incidence of adverse events.

CONCLUSIONS

Rifaximin-loperamide therapy provided rapid symptomatic improvement and greater overall wellness compared with either agent alone.

Current and future developments in travelers' diarrhea therapy

Diarrhea continues to be the leading health problem among international travelers to developing tropical and semi-tropical regions. Despite more than 50 years of research providing information about the etiology and pathogenesis of the disease, the rate of illness and consequences remain unchanged. An estimated 40% of travelers to developing nations will become ill with diarrhea. Although travelers' diarrhea is considered a self-limited disease, novel and effective approaches to disease prevention and treatment have been realized in recent years. Also, recent evidence has identified a potential for long-term complications of the illness, including postinfectious irritable bowel syndrome. With the advent of poorly absorbed (<0.4%) rifaximin, a treatment option for the common watery diarrhea syndrome equivalent to previously used absorbed antibacterial drugs has emerged. Rifaximin with an excellent safety profile and limited potential to induce coliform resistance, prevents most of the diarrhea that would otherwise occur. With further studies in different settings, new consideration should be given to the routine use of chemoprophylaxis for travelers to high-risk countries. Antibacterial drugs will continue to be the optimal treatment for travelers' diarrhea subjects for the most part caused by bacterial enteropathogens and shorten the duration of diarrhea by 1-2 days compared with no active drug treatment.

Prevention and self-treatment of traveler's diarrhea

Of the millions who travel from the industrialized world to developing countries every year, between 20% and 50% will develop at least one episode of diarrhea, making it the most common medical ailment afflicting travelers. Although usually a mild illness, traveler's diarrhea can result in significant morbidity and hardship overseas. Precautions can be taken to minimize the risk of developing traveler's diarrhea, either through avoidance of potentially contaminated food or drink or through various prophylactic measures, including both nonpharmacological and antimicrobial strategies. If diarrhea does develop despite the precautions taken, effective treatment-usually a combination of an antibiotic and an antimotility agent-can be brought by the traveler and initiated as soon as symptoms develop. In the future, vaccines-several of which are in the advanced stages of clinical testing-may be added to the list of prophylactic measures.