Current concepts in travelers' diarrhea: epidemiology, antimicrobial resistance and treatment

Genomic, transcriptomic, and phenotypic differences among archetype Shigella flexneri strains of serotypes 2a, 3a, and 6

IMPORTANCE

Given the genomic diversity between S. flexneri serotypes and the paucity of data to support serotype-specific phenotypic differences, we applied in silico and in vitro functional analyses of archetype strains of 2457T (Sf2a), J17B (Sf3a), and CH060 (Sf6). These archetype strains represent the three leading S. flexneri serotypes recommended for inclusion in multivalent vaccines. Characterizing the genomic and phenotypic variation among these clinically prevalent serotypes is an important step toward understanding serotype-specific host-pathogen interactions to optimize the efficacy of multivalent vaccines and therapeutics. This study underpins the importance for further large-scale serotype-targeted analyses.

Effects of El Niño/La Niña on the Number of Imported Shigellosis Cases in the Republic of Korea, 2004-2017

Shigellosis is a major diarrheal disease in low- and middle-income countries. Although the incidence of such diseases in South and Southeast Asia has been associated with climate fluctuations linked to the El Niño-Southern Oscillation (ENSO), the impact of ENSO on shigellosis infections remains unknown. Data reported to being infected with shigellosis while traveling abroad from 2004 to 2017 were obtained from the Korea Centers for Disease Control and Prevention. We investigated the relationship between the Oceanic Niño Index (ONI) and Indian Ocean Dipole Mode Index and the relative risk of shigellosis in outbound travelers using distributed lag linear and non-linear models. From 2004 to 2017, 87.1% of imported shigellosis was infected in South and Southeast Asian countries. The relative risk of imported shigellosis infection in outbound travelers increased as the ONI decreased. In the association with the five-month cumulative ONI, the relative risk of infection continuously increased as the La Niña index gained strength. Climate fluctuations associated with the La Niña phenomenon in South and Southeast Asian countries can lead to issues in sanitation and water safety. Our findings suggest that the decreasing trend in the ONI is associated with an increased incidence of shigellosis in these countries.

Shigellosis in Subjects with Traveler's Diarrhea Versus Domestically Acquired Diarrhea: Implications for Antimicrobial Therapy and Human Immunodeficiency Virus Surveillance

An increase of sexually transmitted shigellosis is currently being reported in developed countries. In addition, travel-related shigellosis can introduce resistant strains that could be disseminated within this new scenario. Epidemiological features and antimicrobial susceptibility of shigellosis depending on where infection was acquired were investigated. From 2008 to 2013, subjects with shigellosis were studied. Patients were classified according to acquisition of Shigella as traveler's diarrhea (TD) or domestically acquired diarrhea (DAD). Ninety cases of shigellosis were identified: 76 corresponding to the TD group and 14 to the DAD group. In the DAD group, most of patients were human immunodeficiency virus (HIV)-positive men who have sex with men (MSM), being shigellosis associated to male sex (P = 0.007) and HIV infection (P < 0.0001). S. sonnei (47.8%) and S. flexneri (42.2%) were the predominant species. The highest resistance was detected for trimethoprim/sulfamethoxazole (SXT) (81.8%), followed by ampicillin (AMP) (37.8%) and ciprofloxacin (CIP) (23.3%). Resistant Shigella strains were more frequent in subjects with TD than those with DAD, although only for CIP the difference was significant (P = 0.034). Continuous monitoring of patients with shigellosis is necessary to control the spread of resistant Shigella strains and for effective therapy. Men with shigellosis who have not traveled to an endemic area should be screened for HIV infection.

A case-control study of incident rheumatological conditions following acute gastroenteritis during military deployment

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.

[Acute infectious diarrhea]

Acute infectious diarrhea has various causes: bacterial diarrhea with invasive or toxigenic mechanisms, especially frequent in hot regions and in travelers; viral diarrheas, frequent and cosmopolitan in children but also adults; and parasitic diarrhea, less frequent, and generally in subtropical areas. The major concerns involve the risk of complications, essentially dehydration and malnutrition, especially in vulnerable patients: young children, the elderly, and patients with immunosuppression, for whom rehydration is urgent. Diagnosis of diarrhea requires clinical assessment and history: underlying illnesses, severity of symptoms, presence and extent of dehydration and other clinical symptoms, travel history, known outbreaks, and pathogenic mechanism (invasive or toxigenic). Initial therapy should always include oral or parenteral rehydration; antimotility agents are generally not indicated; specific antibiotic treatment is not systematically indicated, except for invasive or dysenteric diarrhea and in immunosuppressed patients.

Trends in antimicrobial resistance in Campylobacter spp. causing traveler's diarrhea

The aim of this study was to analyze the evolution of the levels of resistance to nine antimicrobial agents in clinical isolates of Campylobacter spp. causing traveler's diarrhea during the period from 1993 to 2003. The antimicrobial resistance levels to ampicillin, amoxicillin plus clavulanic acid, chloramphenicol, tetracycline, erythromycin, gentamicin, clindamicin, nalidixic acid and ciprofloxacin were established by the method of Kirby-Bauer. Two subperiods (1993-1998 and 1999-2003) were chosen to compare the evolution of the levels of antimicrobial resistance. Mantel-Haenszel or Fisher's exact test was performed to determine statistical significance. High levels of resistance to four out of nine antimicrobial agents tested were detected: ampicillin (66.3%), nalidixic acid (52.2%), ciprofloxacin (46.7%), and tetracycline (42.4%). In addition, resistance levels of 20.6% to amoxicillin plus clavulanic acid were detected. An increase in the resistance levels between the two subperiods analyzed for those five antimicrobial agents was observed. This increase was statistically significant for ampicillin, nalidixic acid, and ciprofloxacin. Two cases of therapeutic failure during treatment with ciprofloxacin were detected. The level of resistance to the most commonly used antibacterial agents in the developing world is increasing in Campylobacter spp., the increase in the resistance to quinolones being of special concern.

Traveler's diarrhea

Travelers' diarrhea is common. Between 8% and 50% of travelers develop diarrhea; incidence depends on the country visited. The attack rate is highest for travelers from a developed country who visit a developing country. Children are at particular risk. Travelers' diarrhea is usually acquired through ingestion of fecally contaminated food and water. Most cases are due to a bacterial pathogen, commonly, Escherichia coli, and occur within the first few days after arrival in a foreign country. More than 90% of episodes develop within the first 2 wk of initiation of travel. Dehydration is the most common complication. Water and electrolyte replenishment is important and can usually be accomplished with an oral rehydration solution. Judicious use of an antimotility agent and antimicrobial therapy reduces the duration and severity of diarrhea. Pretravel education on hygiene and on the safe selection of food items is important in minimizing episodes. Dukoraltrade mark (Aventis Pharma Ltd., Auckland, New Zealand) vaccine should be considered for travelers who are 2 y of age or older and who will be visiting an area associated with risk of infection due to enterotoxigenic E coli or Vibrio cholerae. Typhoid vaccine is recommended for travelers who will be visiting areas with poor sanitation and hygiene.