Travelers' diarrhea. Epidemiology, prevention, and self-treatment

Predictors of aetiology and outcomes of acute gastrointestinal illness in returning travellers: a retrospective cohort analysis

BACKGROUND

Gastrointestinal illness is a major cause of morbidity in travellers and is a common reason for presentation to healthcare services on return. Whilst the aetiology of imported gastrointestinal disease is predominantly infectious, outcomes are variable due to a range of phenomena such as post-infectious irritable bowel syndrome, drug resistance and occult pathology (both infectious and non-infectious). Previous studies have focussed on predictors of aetiology of gastrointestinal disease in travellers; we present a retrospective study combining both aetiological and early outcome data in a large cohort of returned travellers.

METHOD

We identified 1450 patients who attended our post-travel walk-in clinic with gastrointestinal symptoms between 2010 and 2016. Demographic, travel, clinical and laboratory data was collected through case note review. Logistic regression analysis to examine correlates of aetiology and outcome were performed in R (CRAN Project 2017).

RESULTS

Of 1450 patients in our cohort 153 reported bloody diarrhoea and 1081 (74.6%) reported non-bloody diarrhoea. A definitive microbiological diagnosis was made in 310 (20.8%) of which 137 (9.4%) had a parasite identified and 111 (7.7%) had a bacterial cause identified. Factors associated with a parasitological diagnosis included history of travel to South Asia (aOR = 2.55; 95%CI 1.75-3.70, p < 0.0001) and absence of bloody diarrhoea (aOR = 0.22; 95%CI 0.066-0.53, p < 0.005). Factors associated with a bacteriological diagnosis included male gender (aOR = 1.69; 95%CI 1.10-2.62, p < 0.05), an age < 37 years on presentation (aOR = 2.04; 95%CI 1.25-3.43, p < 0.01), white cells on stool microscopy (aOR = 3.52; 95%CI 2.09-5.86, p < 0.0001) and a C-reactive protein level of >5iu/dL (aOR = 4.68; 95%CI 2.91-7.72, p < 0.0001). The majority (1235/1450, 82.6%) reported full symptomatic resolution by the first follow up visit; factors associated with lack of symptomatic resolution included female gender (aOR = 1.45 95%CI 1.06-1.99, p < 0.05), dysenteric diarrhoea (aOR = 2.14 (95%CI 1.38-3.25, p < 0.0005) and elevated peripheral leukocyte count (aOR = 1.58 95%CI 1.02-2.40, p < 0.05).

CONCLUSIONS

In a cohort of returned travellers, we were able to identify multiple factors that are correlated with both aetiology and outcome of imported gastrointestinal syndromes. We predict these data will be valuable in the development of diagnostic and therapeutic pathways for patients with imported gastrointestinal infections.

Entamoeba histolytica infections in wild and semi-wild orangutans in Sumatra and Kalimantan

Key to the success of orangutan conservation management practices is the prevention of the introduction of infectious diseases to the remaining populations. Previous reports of Entamoeba spp. positive orangutans are of concern as Entamoeba spp. infection has been linked to morbidity and mortality in primates. It remains to be determined if the Entamoeba species infecting orangutans is the pathogenic Entamoeba histolytica. Orangutan fecal samples have been collected from orangutans from sites in Sumatra (Bukit Lawang, Ketambe, and Suaq, 241 samples from 64 individuals), and two sites in Kalimantan (Sebangau and Tuanan, 129 samples from 39 individuals). All samples were from wild orangutans except for a proportion from Sumatra which were from semi-wild (108 samples, 10 individuals). E. histolytica-specific nested PCR assays were carried out on the fecal samples. A total of 36 samples from 17 individuals tested positive for E. histolytica. When compared with published sequences using NCBI BLAST the E. histolytica positive samples showed a 98-99% concordance. The majority (76%, n = 36) of the positive isolates came from semi-wild orangutans in Bukit Lawang. This study supports the growing body of evidence that contact with humans is an important risk factor for infection of wild primates with E. histolytica.

New Tools to Test Stool: Managing Travelers' Diarrhea in the Era of Molecular Diagnostics

Travelers' diarrhea affects up to 60% of visitors to tropical and subtropical regions. Although symptoms are generally self-limited, some infections are associated with significant morbidity and occasional mortality. Newer molecular diagnostic techniques allow for highly sensitive, specific, and expeditious testing of a wide range of potential pathogens. Identification of the causative pathogen of travelers' diarrhea allows for targeted therapy and management and a reduction in empiric broad-spectrum coverage.

Case-Case Analysis Using 7 Years of Travelers' Diarrhea Surveillance Data: Preventive and Travel Medicine Applications in Cusco, Peru

AbstractIn Cusco, Peru, and South America in general, there is a dearth of travelers' diarrhea (TD) data concerning the clinical features associated with enteropathogen-specific infections and destination-specific risk behaviors. Understanding these factors would allow travel medicine providers to tailor interventions to patients' risk profiles and travel destination. To characterize TD etiology, evaluate region-specific TD risk factors, and examine relationships between preventive recommendations and risk-taking behaviors among medium- to long-term travelers' from high-income countries, we conducted this case-case analysis using 7 years of prospective surveillance data from adult travelers' presenting with TD to a physician in Cusco. At the time of enrollment, participants provided a stool sample and answered survey questions about demographics, risk behaviors, and the clinical features of illness. Stool samples were tested for norovirus (NV), bacteria, and parasites using conventional methods. Data obtained were then analyzed using case-case methods. NV (14%), enterotoxigenic Escherichia coli (11%), and Campylobacter (9%), notably ciprofloxacin-resistant Campylobacter, were the most frequently identified pathogens among adults with TD. Coinfection with multiple enteropathogens occurred in 5% of cases. NV caused severe disease relative to other TD-associated pathogens identified, confining over 90% of infected individuals to bed. Destination-specific risk factors include consumption of the local beverage "chicha," which was associated with Cryptosporidium infection. Preventive interventions, such as vaccines, directed against these pathogens could significantly reduce the burden of TD.

Water distribution system deficiencies and gastrointestinal illness: a systematic review and meta-analysis

BACKGROUND

Water distribution systems are vulnerable to performance deficiencies that can cause (re)contamination of treated water and plausibly lead to increased risk of gastrointestinal illness (GII) in consumers.

OBJECTIVES

It is well established that large system disruptions in piped water networks can cause GII outbreaks. We hypothesized that routine network problems can also contribute to background levels of waterborne illness and conducted a systematic review and meta-analysis to assess the impact of distribution system deficiencies on endemic GII.

METHODS

We reviewed published studies that compared direct tap water consumption to consumption of tap water re-treated at the point of use (POU) and studies of specific system deficiencies such as breach of physical or hydraulic pipe integrity and lack of disinfectant residual.

RESULTS

In settings with network malfunction, consumers of tap water versus POU-treated water had increased GII [incidence density ratio (IDR) = 1.34; 95% CI: 1.00, 1.79]. The subset of nonblinded studies showed a significant association between GII and tap water versus POU-treated water consumption (IDR = 1.52; 95% CI: 1.05, 2.20), but there was no association based on studies that blinded participants to their POU water treatment status (IDR = 0.98; 95% CI: 0.90, 1.08). Among studies focusing on specific network deficiencies, GII was associated with temporary water outages (relative risk = 3.26; 95% CI: 1.48, 7.19) as well as chronic outages in intermittently operated distribution systems (odds ratio = 1.61; 95% CI: 1.26, 2.07).

CONCLUSIONS

Tap water consumption is associated with GII in malfunctioning distribution networks. System deficiencies such as water outages also are associated with increased GII, suggesting a potential health risk for consumers served by piped water networks.

Knowledge, attitudes, and practice of travelers' diarrhea management among frontline providers

BACKGROUND

Many studies have found acute gastrointestinal infections to be among the most likely reason for clinic visits among forward deployed soldiers and are considered a significant contributor to morbidity in this population. This occurs despite the controlled food and water distribution systems under which military populations operate. Furthermore, recent studies have indicated that providers often fail to appropriately identify and treat the typical causes of these infections. To adequately address this issue, an assessment of gaps in knowledge, practice, and management of acute diarrhea in deployed troops was conducted.

METHODS

A multiple-choice survey was developed by clinical researchers with expertise in travelers' diarrhea (TD) and provided to a convenience sample of clinical providers with a broad range of training and operational experience. The survey evaluated provider's knowledge of TD along with their ability to identify etiologies of various syndromic categories of acute gastrointestinal infections. Providers were also queried on selection of treatment approaches to a variety of clinical-based scenarios.

RESULTS

A total of 117 respondents completed the survey. Most were aware of the standard definition of TD (77%); however, their knowledge about the epidemiology was lower, with less than 24% correctly answering questions on etiology of diarrhea, and 31% believing that a viral pathogen was the primary cause of watery diarrhea during deployment. Evaluation of scenario-based responses showed that 64% of providers chose not to use antibiotics to treat moderate TD. Furthermore, 19% of providers felt that severe inflammatory diarrhea was best treated with hydration only while 25% felt hydration was the therapy of choice for dysentery. Across all provider types, three practitioner characteristics appeared to be related to better scores on responses to the nine management scenarios: having a Doctor of Medicine or Doctor of Osteopathy degree, greater knowledge of TD epidemiology, and favorable attitudes toward antimotility or antibiotic therapy.

CONCLUSION

Results from this survey support the need for improving knowledge and management of TD among deploying providers. The information from this study should be considered to support the establishment and dissemination of military diarrhea-management guidelines to assist in improving the health of military personnel.

Outcomes of diarrhea management in operations Iraqi Freedom and Enduring Freedom

INTRODUCTION

Among deployed U.S. military personnel, a sub-population of international travelers, acute infectious diarrhea continues to be a leading cause of morbidity and a potential threat to military effectiveness.

METHODS

To assess outcomes and satisfaction of diarrhea management in the field, a systematic survey was given to military personnel during mid- or post-deployment from Iraq or Afghanistan, from January through August 2004.

RESULTS

Sixty-three percent of those surveyed reported at least one episode of diarrhea, while less than half sought care for their symptoms. Overall, trends of decreased post-treatment duration were noted as traveler's diarrhea therapy modalities grew more complex, controlling for severity of illness at presentation. Among those reporting diarrhea, the greatest level of satisfaction was seen in treatment with IV fluids (59%) followed by antibiotics (46%) and loperamide (40%). The greatest amount of dissatisfaction was seen in treatments with oral fluids only.

CONCLUSION

While current standard of care is self-treatment of diarrhea in civilian travelers, the U.S. military lacks standards outlining self-treatment of personnel at the individual level. Further research is needed to develop treatment guidelines on diarrhea management during military deployment.

A global study of pathogens and host risk factors associated with infectious gastrointestinal disease in returned international travellers

OBJECTIVES

Infectious gastrointestinal disease (IGD) is a significant cause of morbidity in returned international travellers. This study aims to elucidate host and travel characteristics associated with IGD presentation, and describe the broad spectrum of aetiological pathogens responsible by geographic region of acquisition and reason for travel.

METHODS

We analyzed demographic, clinical and microbiological data recorded for ill, returned international travellers presenting to GeoSentinel Surveillance Network sites globally during the period September 1996-December 2005.

RESULTS

A total of 25,867 returned travellers were analyzed, of whom 7442 (29%) patients had a total of 8273 IGD diagnoses. Multivariate analysis demonstrated that IGD presentation was associated significantly with female sex (OR: 1.11; p=0.001); younger age group; attending a pre-travel medical appointment (OR: 1.28; p<0.0001); and travelling for the reason of tourism. Travelling for longer periods (>28 days) was associated with lower risk (OR: 0.93; p=0.04). Of the 2902 clinically significant pathogens isolated, 65% were parasitic, 31% bacterial and 3% viral. Presentation of IGD by specific pathogen varied markedly dependent on geographic region of recent travel, and reason for travel.

CONCLUSIONS

Host characteristics, region of travel and category of traveller, significantly impact on the relative likelihood of presenting with a broad range of pathogen-specific IGD.

Travellers' diarrhoea: health advice for travellers

Travellers' diarrhoea is a frequent problem for travellers. Access to a safe water supply when travelling, is undoubtedly a paramount issue. Water and food precautions are important for travellers to be aware of and followed, as is attention to general hygiene. In some situations, chemoprophylaxis and standby treatment with antibiotics may be needed. It is essential that travellers, especially those travelling with young children, be familiar with the use of oral rehydration solutions and the prevention of dehydration.

Antimicrobial prevention and therapy for travelers' infection

International journeys are increasing and more than 70 million people from industrialized countries cross the borders of tropical countries every year. More than 50% of them will suffer from some form of infectious illness, ranging from mild travelers' diarrhea to severe dengue fever to fatal malaria, with a wide spectrum of microbiological entities. Travel-related respiratory infections, including TB, and sexually transmitted infections are also increasingly reported. Awareness of travel-related risk is not always adequate among international travelers. Specific training on travel medicine-related issues, as well as better diagnostic facilities for imported diseases, is crucial for physicians and nurses in industrialized countries.

Bacterial gut infections

Infections of the bowel as a result of bacterial enteropathogens are one of the most common medical problems. The use of novel molecular biology techniques and the recent development of new antimicrobial drugs and vaccines are helping us to identify, understand, treat and prevent these infections.

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.

Use of probiotics in children with acute diarrhea

Probiotics, defined as microbial cell preparations or components of microbial cells that have a beneficial effect on the health and well being of the host, have traditionally been used to treat and prevent a variety of infections. Beneficial effects of probiotics in acute infectious diarrhea in children seem to be: (i) moderate; (ii) strain-dependent; (iii) dose dependent; (iv) significant in watery diarrhea and viral gastroenteritis, but non-existent in invasive, bacterial diarrhea; and (v) more evident when treatment with probiotics is initiated early in the course of disease. Three large, randomized controlled trials (RCTs) provide evidence of a very modest effect (statistically significant, but of questionable clinical importance) of some probiotic strains (Lactobaccillus GG, Lactobaccillus reuteri, Bifodobacterium lactis) on the prevention of community-acquired diarrhea. We have found conflicting evidence from four RCTs on the efficacy of Lactobacillus GG and B. bifidum and Streptococcus thermophilus in the prevention of nosocomial diarrhea in children. Two RCTs in children provide evidence of a moderate beneficial effect of Lactobacillus GG in the prevention of antibacterial-associated diarrhea (AAD), but results in adults are conflicting. Data on the efficacy of other probiotic strains in AAD in children are very limited. In conclusion, to date, the most extensively studied and best documented clinical application of probiotics in children is for the treatment of acute watery diarrhea of rotaviral or presumably viral etiology. Studies documenting effects in other types of diarrheal diseases in children are limited, although some preliminary results are promising. The effects of different probiotic microorganisms are not equal. Only very few probiotic strains have been tested rigorously in RCTs. Many questions remain to be answered. Future clinical trials should evaluate carefully selected, precisely defined probiotic strains and address clinically important endpoints.

Self-reported description of diarrhea among military populations in operations Iraqi Freedom and Enduring Freedom

BACKGROUND

Infectious diarrhea is among the most common medical problems associated with military deployments and has been reported as a frequent problem for troops currently deployed to Iraq and Afghanistan. Lacking is information describing clinical presentation, risk behaviors, and treatment of travelers' diarrhea in this population.

METHODS

An anonymous cross-sectional survey was conducted among 15,459 US military personnel deployed to Southwest Asia during 2003 to 2004.

RESULTS

Overall, diarrhea was commonly reported (76.8% in Iraq and 54.4% in Afghanistan) and was frequently severe (more than six stools/d) (20.8% in Iraq and 14.0% in Afghanistan) or associated with fever (25.8%), vomiting (18% with diarrhea and 16.5% without), persistent symptoms (>14 d, 9.8%), or chronic symptoms (>30 d, 3.3%). Diarrhea was associated with time spent off military compounds and eating local food. Over 80% of respondents sought care for their symptoms, usually at the lowest echelon of care (field medic), and were most often treated with either loperamide or an antibiotic. Self-treatment with loperamide or Pepto-Bismol was also common and successful with only 9% of self-treated individuals reporting seeking further medical care.

CONCLUSIONS

Infectious diarrhea is a common problem for US military personnel, and associated fevers and vomiting are more common than in past conflicts in the region. As with past studies, time spent off base and local food consumption, both more common in Iraq than Afghanistan, continue to be the most important risk factors for acquiring diarrhea. The majority of soldiers reported seeking care for diarrhea, but appropriate treatment, including self-treatment with over-the-counter medicines, was generally successful. Further studies should be conducted to evaluate appropriate treatment algorithms, including the use of self-treatment, for deployed military personnel.

Prevention of travel-related infectious diseases in families of internationally adopted children

Pretravel consultation before international adoption must encompass standard advice for those who travel, advice for those who are exposed to the newly adopted child, and information about caring for a new child during travel. Children who travel to meet siblings may need special accommodations before and during travel. Data on the health of internationally adopted children illustrate the risk of exposing family members and close contacts to some infectious diseases during or after international adoption. Parents, family members, and close contacts of the newly adopted child should be given advice to reduce their own and their child's risk. Targeted preadoption counseling, close attention to hygiene and safety advice, and prompt identification and treatment of infections lead to the safest and most trouble-free adoption travel experience.

Correlation between adherence to precautions issued by the WHO and diarrhea among long-term travelers to India

BACKGROUND

Travelers' diarrhea is the most common infectious disease afflicting travelers to developing countries. Most studies investigating the benefits of recommendations regarding the consumption of food and water have focused on short-term travelers. We investigated the benefits of adherence to the precautions from the World Health Organization (WHO) among long-term travelers.

METHODS

We asked 140 incidental travelers in India traveling for at least 2 months to complete a questionnaire about their adherence to the WHO precautions and the occurrence of diarrhea. Adherence was graded on a scale of 1 to 6 (least to most).

RESULTS

The mean age of the 114 travelers whose questionnaires were eligible was 26.6 +/- 5.7 years, and the median duration of their trip was 5 months. None of them adhered strictly to the entire set of rules. The mean individual adherence was 3.4 (range 1.2-5.8). The vast majority of the travelers (83%) suffered from diarrhea. Most travelers (60%) had diarrhea for up to 3% of their journey time. Diarrhea was accompanied by fever among 18% and necessitated hospitalization in 3%. Forty-five percent indicated that they had lost traveling days due to diarrhea, for an average of 0.7% of the traveling time. We found no correlation between the percentage of traveling time with diarrhea and the following variables: adherence to the WHO recommendations, receipt of advice regarding prevention, duration of the trip, age, sex, and nationality of the travelers.

CONCLUSIONS

Dietary self-restraint of travelers as proposed by the WHO is both difficult to comply with and lacks a proven value for the long-term traveler to a developing country.

Travel and health status: a survey follow-up study

BACKGROUND

To date there is little sound knowledge on the relationship between travel and health status as perceived by the traveller. Our aim was to investigate the frequency and risk factors of travel-associated illnesses and injuries and identify potential protective factors.

METHODS

All adults enrolled in a health insurance scheme who planned to travel in 2002 were eligible for participation in a baseline survey. Pre-travel written questionnaires and post-travel telephone interviews were conducted with responders. We analysed travel-associated health problems using descriptive methods and multivariate logistic regression.

RESULTS

From 8316 persons who returned a pre-travel questionnaire, a sample of 2384 were chosen, of whom 1471 completed post-travel interviews. 10.1% of all travellers reported travel-associated illnesses, and 1.8% suffered from injuries during travel. Among travellers to European destinations, 6.0% reported an illness as opposed to 16.2% of travellers to overseas destinations. Predictors for travel-associated illness were age <30 years (OR 1.48), duration of travel >4 weeks (OR 3.35) and travel destination. Perceived health status as scored by the travellers improved after travel. The frequency of medical consultations and personal health-related expenses decreased significantly shortly after travel.

CONCLUSIONS

In this study, travel had a positive effect on the perceived health status of the traveller. The positive effects of travel seemed to outweigh the impact of health problems. Travel did not lead to increased health-related costs, neither in individual health expenses nor indirectly through increased medical consultation rates.

Pathophysiology and impact of enteric bacterial and protozoal infections: new approaches to therapy

Despite numerous scientific advances in the past few years regarding the pathogenesis, diagnostic tools and treatment of infectious enteritis, enteric infections remain a serious threat to health worldwide. With globalization of the food supply, the increase in travel, mass food processing and antibiotic resistance, infectious diarrhea has become a critical concern for both developing and developed countries. Oral rehydration therapy has been cited as the most important medical discovery of the century due to the millions of lives that have been saved. However, statistics concerning diarrhea-induced mortality and the highly underestimated morbidity continue to demonstrate the severity of the problem. A more complete understanding of the pathogenesis of infectious diarrhea and potential new vaccines and effective treatments are badly needed. In addition, public health preventive actions, such as early detection of outbreaks, care with food, water and sanitation and, where relevant, immunization, should be considered a priority. This article provides an overview of the epidemiological impact, pathogenesis and new approaches to the management of enteric infections.

Pharmacotherapy, vaccines and malaria advice for HIV-infected travellers

Since the introduction of effective antiretroviral therapy (ART), HIV-infected individuals are travelling more frequently and international travel has become much safer. Specific concerns include the safety of ART during travel, drug adherence and interaction considerations, and effects of immunosuppression. This review describes potentially important infections, vaccine effectiveness, safety and special approaches for their use, and HIV-related issues regarding predeparture counselling. With advanced immunosuppression (CD4+ T-cell count < 200/microl or < 14%), the immunogenicity of several vaccines is reduced, complications could occur after live attenuated vaccines and certain infections acquired during travel may be more frequent or severe. Challenges include the best options for malaria chemoprophylaxis, standby treatment and medical follow-up of the increasing number of HIV-infected long-term travellers.

Traveller's diarrhoea

Traveller's diarrhoea affects over 50% of travellers to some destinations and can disrupt holidays and business trips. This review examines the main causes and epidemiology of the syndrome, which is associated with poor public health infrastructure and hygiene practices, particularly in warmer climates. Although travellers may be given common sense advice on avoidance of high-risk foods and other measures to prevent traveller's diarrhoea, adherence to such advice is sometimes difficult and the evidence for its effectiveness is contradictory. However, non-antimicrobial means for prevention of traveller's diarrhoea are favoured in most settings. A simple stepwise approach to the management of traveller's diarrhoea includes single doses or 3-day courses of antimicrobials, often self administered. The antibiotics of choice are currently fluoroquinolones or azithromycin, with an emerging role for rifaximin. In the long term, there will be greater benefit and effect on the health of local inhabitants and travellers from improving public health and hygiene standards at tourist destinations.

Preparing the traveller

The four steps for giving travellers the foundation for healthy journeys are to assess their health, analyse their itineraries, select vaccines, and provide education about prevention and self-treatment of travel-related diseases. This process takes time. Since there is a risk of information overload, travellers should leave the clinic with some written advice for reinforcement. The order of these steps can be tailored to what best suits the travel clinic, but vaccinating early in the process allows monitoring for adverse reactions. Face-to-face discussion is vital for explaining the use and side-effects of medications. Those who provide a travel medicine service should be seeing many travellers and should seek specialist training. In 2003, the International Society of Travel Medicine introduced a certificate of knowledge examination in travel medicine. We cannot make travellers bullet-proof but it is possible to make them bullet-resistant. The pre-travel visit should minimise health risks specific to the journey, give travellers the capability to handle most minor medical problems, and allow them to identify when to seek local care during the trip or on return.

Behavior of enteroaggregative Escherichia coli in bottled spring and mineral water

The ability of enteroaggregative Escherichia coli (EAEC) to survive in bottled mineral and spring water at common storage temperatures was investigated. Filtered mineral and spring waters were inoculated with EAEC (ca. 10(4) CFU/ml) and stored at 4, 10, and 23 degrees C. Water samples were analyzed every 3 days for viable EAEC by plating on tryptic soy agar plates over 60 days of storage. EAEC survived for the duration of the study in both mineral and spring waters. EAEC survival levels were significantly higher (P < 0.01) at 23 and 10 degrees C than at 4 degrees C. Furthermore, EAEC survival levels were significantly higher (P < 0.01) in mineral water than in spring water at 4 and 10 degrees C. The results of this study indicate that EAEC can survive in bottled mineral and spring waters for long periods of storage at 4, 10, and 23 degrees C. The ability of EAEC to survive in bottled water indicates that the source water for bottling industries must be kept free of contamination. Furthermore, the refrigeration of bottled water is recommended to minimize the growth of EAEC in water.

Travelling with children

Today children are more frequently travelling worldwide, thus increasing their exposure to exotic pathogens and unexpected environmental hazards. In order to ensure the safety of their health while travelling, children should see the person in charge of their medical care well in advance of their journey to assess the status of their routine immunizations and to evaluate their need for any travel-specific vaccines. In this review we touch on some of the most critical pre-travel vaccines and precautions needed for travelling children.

Prevention and self-treatment of travelers' diarrhea

Of the 50 million people 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 ailment of travel. Although usually a mild illness, travelers' diarrhea can result in significant morbidity and hardship while overseas. Precautions can be taken to minimize the risk of developing diarrhea. If diarrhea does develop despite precautions, effective treatment, usually a combination of an antibiotic and an antimotility agent, can be taken along and started by the traveler at the onset of symptoms.

Recent Advances and New Challenges in Travel Medicine

Recent advances in travel medicine include the use of computer resources to obtain information on outbreaks and recommendations to travelers, the introduction of atovaquone/proguanil as chemoprophylaxis and treatment for malaria, the use of azithromycin as an alternative in the self-treatment of traveler's diarrhea, and the combination of hepatitis A and hepatitis B vaccines. At the same time, new challenges continue to appear. Shifts in the distribution of infections, such as West Nile virus and dengue fever, underscore the need for up-to-date information. Well-known infectious diseases, such as polio, meningococcal meningitis, and influenza are appearing in unexpected ways and settings. It is increasingly clear that travelers, while at risk for infections, also play a role in the global dispersal of pathogens, such as certain serogroups of Neisseria meningitidis and influenza. Increasing drug resistance affects the choice of drugs for treatment and chemoprophylaxis, and decisions about use of vaccines. Newly identified adverse events associated with yellow fever vaccine have prompted enhanced surveillance after vaccination and careful scrutiny of appropriate indications for the vaccine.

Update on Traveler's Diarrhea

Diarrhea is one of the most common health problems among travelers. Although enterotoxigenic Escherichia coli is implicated most commonly, enteroaggregative E. coli has recently been described as a major pathogen. Shigella, Campylobacter, and Salmonella organisms are less common causes of acute diarrhea, and intestinal protozoa are typical causes of protracted diarrhea. Although education is the mainstay of prevention measures, behavior modification has been shown to be difficult. Chemoprevention is rarely required with the availability of effective treatment, but there has been some interest in the use of vaccines. Maintenance of hydration is most important in children. In addition to bismuth preparations and loperamide, newer agents being developed for symptomatic relief include zaldaride maleate and racecadotril. Fluoroquinolones effectively treat severe traveler's diarrhea, and even a single dose may be sufficient. However, with the emergence of resistance, particularly in Campylobacter infection, other agents are required; interest has focused on azithromycin and rifaximin.

Tropical diarrhoea: new developments in traveller's diarrhoea

Traveller's diarrhoea is the most common illness acquired by visitors to developing countries, affecting 20-50% of the 35 million people who travel from industrialized countries each year. Important risk factors include point of origin and destination of the traveller, host factors, and exposure to contaminated food and water. The most common causes of traveller's diarrhoea in adults in developing countries include infection with Escherichia coli, Shigella spp., Salmonella spp., Campylobacter spp., Vibrio parahaemolyticus (in Asia), rotavirus (in Latin America), and protozoa (Giardia, Cryptosporidium and Cyclospora spp., and Entamoeba histolytica). No pathogen is identified in over half of patients with traveller's diarrhoea, however. The primary objectives of treatment of traveller's diarrhoea are to reduce the symptoms and duration of diarrhoeal illness, to reduce inconvenience caused by such illness and to prevent cancellation of planned activities. These important objectives are best accomplished by empirical self-therapy with a combination of antimicrobial agents and loperamide. Since the first use of ciprofloxacin, fluoroquinolones have become the drugs of choice in empirical therapy for moderate-to-severe traveller's diarrhoea in adults. The options for children include nalidixic acid, trimethoprim-sulfamethoxazole (along with erythromycin if Campylobacter infection is a possibility) and furazolidone. Education on hygiene and safe food preparation help to prevent many diarrhoeal diseases, including traveller's diarrhoea.

Biotherapeutic agents in the treatment of infectious diarrhea

Biotherapeutic agents offer unique advantages over traditional treatments for infectious diarrhea, and several have been shown to be effective (Table 4). These therapeutic microbial agents are most effective in types of infectious diseases that are associated with a disruption of the normal intestinal microecology (e.g., AAD, C. difficile disease). The impact of biotherapeutic agents on rotaviral diarrhea is of special clinical importance because this is the most common cause of pediatric diarrhea, and there is no defined treatment. Strong efforts need to be made to limit antibiotic exposure in children. Biotherapeutic agents offer a safe and effective nonantibiotic method of treating this important pathogen, especially after the withdrawal of a rotaviral vaccine from the market by the FDA. However, for many biotherapeutic agents, well-done, placebo-controlled trials still are lacking, and not all types of infectious diarrhea respond to these agents. Continued research in this innovative therapeutic area is warranted.

Implementation of pretravel advice: good for malaria, bad for diarrhoea

Pretravel immunizations and health advice can substantially reduce the incidence of travel-related diseases. The aim of this study was to evaluate the implementation of pretravel advice among a homogenous group of students, who received similar written information on vaccination requirements and health advice. They were referred to the travel clinic (50%) or a general practitioner (50%) for vaccination, counselling and prescriptions. Eighty-four out of 110 students (76%) returned the questionnaire. Insect repellent was used by all and only 10 used the repellent for less than 75% of the time spent in malaria endemic areas. Malaria chemoprophylaxis was taken by all but one: chloroquine plus proquanil by 12 and mefloquine by 71. Reported compliance with the dosing regimen was optimal in 64 students, 9 missed one dose and 10 stopped too early. Side effects due to antimalarials were reported by 25 (30%). Diarrhoea during travel occurred in 43 students (51%). Loperamide was used by 34 students with diarrhoea (79%), but only 2 out of 27 students with moderate to severe diarrhoea used the recommended self-treatment with a fluoroquinolone antibiotic. In conclusion, the recommendations of malaria prophylaxis were well implemented by most travellers despite a high incidence of self-reported side effects to antimalarials. The incidence of traveller's diarrhoea was high and the recommendation for early self-treatment of moderate to severe diarrhoea with a fluoroquinolone antibiotic in combination with loperamide was not put into practice.

Diarrhea in the returned traveler

Diarrhea in the returned traveler is a common problem that can be caused by a number of different pathogens. A history of the patient's travel and exposures, the duration of illness, the response to prior treatment, and the clinical syndrome can help to establish a good etiologic differential diagnosis on which further therapy can be based. Many of these patients can be treated empirically with antibiotics, either a fluoroquinolone or azithromycin, without further microbiologic evaluation. Those patients with severe or persistent disease or comorbid illnesses, or those who have failed empiric therapy, should undergo further microbiologic evaluation with directed stool cultures and ova and parasite screening. For those patients with negative evaluations, further empiric therapy may be warranted if syndromes are suggestive of specific agents of infection, such as by Giardia or Cyclospora species. Other patients may require endoscopic evaluation to exclude diagnoses such as tropical sprue or inflammatory bowel disease.

Medical advice for international travelers

Each year, approximately 30 to 40 million Americans travel outside the United States. Although the most popular destinations are Europe, Central America, and the Caribbean, travel to Africa and Asia is increasing substantially. International travel, particularly to developing countries, can be associated with the risk of infectious and noninfectious diseases. These risks can be decreased, eliminated, or modified with vaccinations, prophylactic medications, and education. Optimally, pretravel advice must be individualized to a person's medical history, itinerary, and risk behavior. In addition to risk assessment-based immunizations, issues such as traveler's diarrhea, malaria prophylaxis, sexually transmitted diseases, and management of underlying medical problems must form a part of pretravel management. Adventure or prolonged travel or persons with underlying medical diseases such as insulin-dependent diabetes mellitus, transplantation, immunodeficiencies, and dialysis warrant additional preventive measures. This review primarily updates pretravel management of adults.

Practical management of acute diarrhea

A careful history and physical examination are usually enough to assess illness severity, the need for further labortory tests, and often the cause. Supportive treatment generally suffices However, antibiotic or probiotic therapy should be considered in selected patients.

EnteroaggregativeEscherichia colias a Major Etiologic Agent in Traveler's Diarrhea in 3 Regions of the World

Enteroaggregative Escherichia coli (EAEC) has been reported to cause traveler's diarrhea and persistent diarrhea in children in developing countries and in immunocompromised patients. To clarify the prevalence of EAEC in traveler's diarrhea, we studied 636 US, Canadian, or European travelers with diarrhea: 218 in Guadalajara, Mexico (June--August 1997 and 1998), 125 in Ocho Rios, Jamaica (September 1997--May 1998), and 293 in Goa, India (January 1997--April 1997 and October 1997--February 1998). Stool samples were tested for conventional enteropathogens. EAEC strains were identified by use of the HEp-2 assay. EAEC was isolated in 26% of cases of traveler's diarrhea (ranging from 19% in Goa to 33% in Guadalajara) and was second only to enterotoxigenic E. coli as the most common enteropathogen in all areas. Identification of EAEC reduced the number of cases for which the pathogen was unknown from 327 (51%) to 237 (37%) and explained 28% of cases with unknown etiology. EAEC was a major cause of traveler's diarrhea in 3 geographically distinct study areas.

Preparation of the HIV-infected Traveler to the Tropics

Pre-travel advice and planning can help the HIV-infected traveler minimize the unavoidable risks of tropical travel. Issues to cover: the diagnosis, staging, and stabilization of HIV infection and its sequelae; adequacy of the supply of medications currently used; optimal sources of medical care in planned destinations; potential HIV-related legal restrictions on travel; special risks associated with the medical geography of the traveler's route and planned activities; the need to avoid food-, water-, and vector-borne diseases; any appropriate vaccination, chemoprophylaxis, and antimicrobial agents; and arrangement for adequate medical follow-up upon the traveler's return.

Serum antibody response induced in mice after oral administration of three different antigens of enterotoxigenic Escherichia coli in enteric coated microparticles

BACKGROUND

Gastric digestion of these antigens plays an important role, decreasing the ability to deliver antigens to the gut-associated lymphoid tissue. To overcome this obstacle, microencapsulated antigens from enterotoxigenic Escherichia coli (ETEC) were evaluated for oral immunization of mice.

METHODS

Four groups of 10 each received 3 series of 3 doses each of (1) B subunit of cholera toxin (CTB), similar to heat-labile toxin of ETEC, (2) formalin-killed whole cell ETEC H10407 (FK-ETEC), (3) crude preparation of colonization factor antigen I (CFA/I), or (4) placebo. Serum antibody was measured on day 0 and 60 by ELISA.

RESULTS

In group 1 a CTB antibody response was induced in all mice, 3 with 1:105 titer and 7 with 1:106. These antibodies neutralized cholera toxin-induced steriodogenesis of Y-1 adrenal cells. In group 2, 8 mice developed a whole H10407 bacteria antibody titer of 1:100, one 1:200 and one showed no immune response. In the same group, an anti-CFA/I response was observed in 6 mice and anti-LPS in 4 mice as determined by Western blot. All mice in group 3 showed > 1:104 anti-CFA/I antibody titer. Group 4 mice did not develop an immune response to any ETEC antigens.

CONCLUSIONS

Microencapsulation appears to be a suitable approach for oral vaccination against ETEC and Vibrio cholerae.

Empirical antimicrobial therapy for traveler's diarrhea

Over 7 million cases of traveler's diarrhea, defined as the passage of > or = 3 unformed stools in a 24-h period, occur each year among visitors to developing countries. Bacterial enteric pathogens are the most common etiologic agents isolated. Preliminary clinical results for patients with diarrhea predominantly caused by Campylobacter species have shown that azithromycin may be an effective alternative to fluoroquinolones for the treatment of traveler's diarrhea.

Giardiasis: an elusive cause of gastrointestinal distress

The common protozoan Giardia lamblia has a fecal-oral mode of transmission, usually from contaminated water or food or person-to-person contact. Infection may be asymptomatic or result in a broad spectrum of symptoms-most commonly, subacute illness that is mistaken for other gastrointestinal problems. Although most infections are self-limited, treatment is indicated due to the long duration and the risk of transmission. Several therapeutic agents are available, but none is 100% effective. Prevention for people involved in outdoor sports or recreation and for international travelers includes treatment of all surface water and rigorous personal hygiene.

Impact of changing societal trends on the spread of infections in American and Canadian homes

Infectious diseases continue to exert a heavy toll on human health even in industrialized countries. Recent data from the World Health Organization suggests that infectious diseases are the leading cause of death in the world. Many changing trends in our society have a known or potential impact on infectious disease spread and may have an impact on the normal routine of home hygiene. Important amongst these societal trends are increasing population and life expectancy, changes in urbanization, grouping of susceptibles, increased ambulatory and home care, increased immunosuppression, increased and faster travel, changes in technology, increasing antibiotic resistance as a result of misuse of antibiotics, changes in food and water consumption, and changes in personal cleaning, washing, and laundry practices. This review will highlight these factors and their impact on home hygiene and steps that may be needed to reduce the risk from infections.

Microecologic approaches for traveler's diarrhea, antibiotic-associated diarrhea, and acute pediatric diarrhea

Bacterial and viral diarrhea remain important causes of morbidity and mortality throughout the world. Current concerns with medical costs, increasing frequency of antibiotic resistance, and overuse of antibiotics in general have redirected therapeutic approaches for diarrhea from traditional drugs to the use of living therapeutic organisms. Awareness of the important role of normal flora in the microecology of the intestines in fighting infection, along with the recent availability of well-controlled clinical trials for these agents, has brought microecologic therapies to the forefront of clinical practice.