Traveller's diarrhoea

Infectious agents of food- and water-borne illnesses

Food- and water-borne infections have afflicted mankind since the earliest days of human development and preceded the emergence of civilization. Despite current knowledge of microbial pathogenicity, modern methods of food production and rigorous industrial hygiene, these infections are still commonplace and exact significant health and economic tolls on human populations in all parts of the globe. This review uses data derived from new surveillance networks to survey the current epidemiology of bacterial, protozoan and viral pathogens transmitted by food and water. In addition, we will discuss clinical features of human disease caused by pathogens of current and emerging relevance.

Clinical and epidemiological characteristics of imported infectious diseases in Spanish travelers

INTRODUCTION

Spain could be a potential area in Europe for the development and spread of emerging diseases from the tropics due to its geoclimatic characteristics, but there is little information on infectious diseases imported by travelers. The aim of this article was to analyze clinical-epidemiological characteristics of infectious diseases imported by Spanish travelers from the tropics.

METHODS

A retrospective descriptive study of 2,982 travelers seeking medical advice who return ill from the tropics was conducted. Demographic data, details of travel (destination, type, and duration), preventive measures, clinical syndromes, and diagnoses were analyzed.

RESULTS

Nearly half (46.5%) the travelers had traveled to sub-Saharan Africa; 46.5% reported a stay exceeding 1 month (and almost a quarter more than 6 months). Following pre-travel advice, 69.1% received at least one vaccine and 35.5% took malarial chemoprophylaxis with variations according to geographical area of travel. In all, 58.8% of this took chemoprophylaxis correctly. Most common syndromes were fever 1,028 (34.5%), diarrhea 872 (29.3%), and cutaneous syndrome 684 (22.9%). Most frequent diagnoses were traveler's diarrhea (17.2%), malaria (17%), and intestinal parasites (10.4%). The three main syndromes in travelers to the Caribbean-Central America, Indian subcontinent-Southeast Asia, and other areas were diarrhea, fever, and cutaneous syndrome (p < 0.05); in sub-Saharan Africa were fever, cutaneous syndrome, and diarrhea (p < 0.05); and in South America were cutaneous syndrome, diarrhea, and fever (p < 0.05). Travelers to sub-Saharan Africa showed a higher frequency of malaria, rickettsiosis, filariasis, and schistosomiasis (p < 0.05); those to South America showed cutaneous larva migrants, other ectoparasitosis, and cutaneous/mucocutaneous leishmaniasis; and those to the Indian subcontinent-Southeast Asia showed intestinal parasitosis, arboviriasis, and enteric fever (p < 0.05).

CONCLUSIONS

Increased international travel is a key factor for the development and spread of emerging pathogens. Information on these diseases is essential to establish early warning mechanisms and action plans. Spain represents a unique setting for this.

Giant splenic abscess due to Salmonella enteritidis in a returning traveler

We report the case of an immunocompetent traveler returning from Morocco who presented with a giant splenic abscess, revealing an infection by Salmonella enterica serovar enteritidis.

Bile acids improve the antimicrobial effect of rifaximin

Diarrhea is one of the most common infirmities affecting international travelers, occurring in 20 to 50% of persons from industrialized countries visiting developing regions. Enterotoxigenic Escherichia coli (ETEC) is the most common causative agent and is isolated from approximately half of the cases of traveler's diarrhea. Rifaximin, a largely water-insoluble, nonabsorbable (<0.4%) antibiotic that inhibits bacterial RNA synthesis, is approved for use for the treatment of traveler's diarrhea caused by diarrheagenic E. coli. However, the drug has minimal effect on the bacterial flora or the infecting E. coli strain in the aqueous environment of the colon. The purpose of the present study was to evaluate the antimicrobial effect and bioavailability of rifaximin in aqueous solution in the presence and absence of physiologic concentrations of bile acids. The methods used included growth measurement of ETEC (strain H10407), rifaximin solubility measurements, total bacterial protein determination, and assessment of the functional activity of rifaximin by monitoring inhibition of bacterial beta-galactosidase expression. Solubility studies showed rifaximin to be 70- to 120-fold more soluble in bile acids (approximately 30% in 4 mM bile acids) than in aqueous solution. Addition of both purified bile acids and human bile to rifaximin at subinhibitory and inhibitory concentrations significantly improved the drug's anti-ETEC effect by 71% and 73%, respectively, after 4 h. This observation was confirmed by showing a decrease in the overall amount of total bacterial protein expressed during incubation of rifaximin plus bile acids. Rifaximin-treated samples containing bile acids inhibited the expression of ETEC beta-galactosidase at a higher magnitude than samples that did not contain bile acids. The study provides data showing that bile acids solubilize rifaximin on a dose-response basis, increasing the drug's bioavailability and antimicrobial effect. These observations suggest that rifaximin may be more effective in the treatment of infections in the small intestine, due to the higher concentration of bile in this region of the gastrointestinal tract than in the colon. The water insolubility of rifaximin is the likely explanation for the drug's minimal effects on colonic flora and fecal pathogens, despite in vitro susceptibility.

Review article: rifaximin, a minimally absorbed oral antibacterial, for the treatment of travellers' diarrhoea

BACKGROUND

Travellers' diarrhoea, a common problem worldwide with significant medical impact, is generally treated with anti-diarrhoeal agents and fluid replacement. Systemic antibiotics are also used in selected cases, but these may be associated with adverse effects, bacterial resistance and drug-drug interactions.

AIM

To review the clinical evidence supporting the efficacy and safety of the minimally absorbed oral antibiotic rifaximin in travellers' diarrhoea.

METHODS

PubMed and the Cochrane Register of Controlled Clinical Trials (to January 2010) and International Society of Travel Medicine congress abstracts (2003-2009) were searched to identify relevant publications.

RESULTS

A total of 10 publications were included in the analysis. When administered three times daily for 3 days, rifaximin is superior to placebo or loperamide; it is at least as effective as ciprofloxacin in reducing duration of illness and restoring wellbeing in patients with travellers' diarrhoea, both with and without identification of a pathogen, as well as in diarrhoea caused by Escherichia coli infection. Rifaximin demonstrates only minimal potential for development of bacterial resistance and for cytochrome P450-mediated drug-drug interactions, and its tolerability profile is similar to that of placebo.

CONCLUSION

When antibiotic therapy is warranted in uncomplicated travellers' diarrhoea, rifaximin may be considered as a first-line treatment option because of its favourable efficacy, tolerability and safety profiles.

Best practice in primary care pathology: review 12

This twelfth best practice review examines four series of common primary care questions in laboratory medicine: (i) antiepileptic drug monitoring; (ii) infectious diarrhoea; (iii) methicillin resistant Staphylococcus aureus; and (iv) brain natriuretic peptide. The review is presented in question–answer format, referenced for each question series. The recommendations represent a précis of guidance found using a standardised literature search of national and international guidance notes, consensus statements, health policy documents and evidence-based medicine reviews, supplemented by MEDLINE EMBASE searches to identify relevant primary research documents. They are not standards but form a guide to be set in the clinical context. Most are consensus rather than evidence-based. They will be updated periodically to take account of new information.

Diarrhea A to Z: America to Zimbabwe

PURPOSE

To review international statistics on the morbidity and mortality of diarrhea, pathophysiology, global incidence, and implications for the clinical practice of nurse practitioners (NPs).

DATA SOURCES

Selective review of literature.

CONCLUSIONS

Because of ever-increasing international travel, immigration, and rising awareness of global health issues, NPs must be current on the prevention, diagnosis, and treatment of diarrhea.

IMPLICATIONS FOR PRACTICE

Increased awareness of diarrhea as a significant international health issue mandates that NPs counsel clients who travel to high-risk areas about preventive measures to avoid exposure or manage symptoms while traveling. Guidelines for evidence-based treatments of diarrheal illness are widely available and should be followed.

Salmonella prevalence in slaughtered buffaloes and pigs and antimicrobial susceptibility of isolates in Vientiane, Lao People's Democratic Republic

This is the first report regarding isolation of Salmonella from cecum samples of buffaloes and pigs and characterization of the isolates in Laos. The organisms were isolated from 8% (4/50) of buffaloes and 76% (37/49) of pigs. In buffaloes, 3 animals harbored serotype 9,12: -:1,5, and 1 animal harbored both S. Derby and S. Javiana. In pigs, the most predominant serotypes were S. Derby (51%) followed by S. Anatum (45%), S. Weltevreden (15%) and S. Stanley (5%). The buffalo isolates were susceptible to the antimicrobials tested, whereas the pig isolates showed 10 resistance patterns to 1-5 antibiotics. Of the 59 pig isolates, the resistance rates to tetracycline, streptomycin, ampicillin, sulfamethoxazole-trimethoprim, chloramphenicol, amoxicillin-clavulanic acid and nalidixic acid were 24%, 22%, 14%, 5%, 2%, 2% and 2%, respectively. The results suggest that pigs and buffaloes harbor Salmonella, with a higher prevalence especially in pigs, and all the isolates showed sensitivity to cefotaxime, norfloxacin and ciprofloxacin.

The influence of ligand valency on aggregation mechanisms for inhibiting bacterial toxins

Divalent and tetravalent analogues of ganglioside GM1 are potent inhibitors of cholera toxin and Escherichia coli heat-labile toxin. However, they show little increase in inherent affinity when compared to the corresponding monovalent carbohydrate ligand. Analytical ultracentrifugation and dynamic light scattering have been used to demonstrate that the multivalent inhibitors induce protein aggregation and the formation of space-filling networks. This aggregation process appears to arise when using ligands that do not match the valency of the protein receptor. While it is generally accepted that multivalency is an effective strategy for increasing the activity of inhibitors, here we show that the valency of the inhibitor also has a dramatic effect on the kinetics of aggregation and the stability of intermediate protein complexes. Structural studies employing atomic force microscopy have revealed that a divalent inhibitor induces head-to-head dimerization of the protein toxin en route to higher aggregates.

Proton pump inhibitor use and enteric infections

Proton pump inhibitors (PPIs) and H2 receptor antagonists (H2RAs) are very commonly prescribed drugs and are routinely used in the chronic management of gastro-esophageal reflux disease. Concerns have been raised about the possible association of PPIs with enteric infections. This article reviews the studies that have examined the associations of proton pump inhibitors in particular, and enteric infections.

Prophylactic immunisation against traveller's diarrhoea caused by enterotoxin-forming strains of Escherichia coli and against cholera: does it make sense and for whom?

Traveller's diarrhoea (TD) constitutes the most common disease relevant to travel medicine with ETEC as the leading causative pathogen. Cholera is the most serious, but very rare form of TD. ETEC and cholera share pathogenic mechanisms by producing a toxin that has an 80% amino acid homology. A consensus of German-speaking experts sees the indication to use the whole cell/B subunit oral cholera vaccine (WC--BS) if cholera is a risk for aid workers or travellers with an anticipated threat of cholera who stay under poor hygienic conditions. The use of the vaccine should be considered in the indication to avoid ETEC TD for travellers with predisposing illness or medication or for travellers at risk to develop a serious course.

International foodborne outbreak of Shigella sonnei infection in airline passengers

During 22-24 August 2004, an outbreak of Shigella sonnei infection affected air travellers who departed from Hawaii. Forty-seven passengers with culture-confirmed shigellosis and 116 probable cases who travelled on 12 flights dispersed to Japan, Australia, 22 US states, and American Samoa. All flights were served by one caterer. Pulsed-field gel electrophoresis of all 29 S. sonnei isolates yielded patterns that matched within one band. Food histories and menu reviews identified raw carrot served onboard as the likely vehicle of infection. Attack rates for diarrhoea on three surveyed flights with confirmed cases were 54% (110/204), 32% (20/63), and 12% (8/67). A total of 2700 meals were served on flights with confirmed cases; using attack rates observed on surveyed flights, we estimated that 300-1500 passengers were infected. This outbreak illustrates the risk of rapid, global spread of illness from a point-source at a major airline hub.

Cost-benefit of WC/rBS oral cholera vaccine for vaccination against ETEC-caused travelers' diarrhea

BACKGROUND

The most common infectious health problem encountered by travelers to countries in the developing region is travelers' diarrhea (TD), with enterotoxigenic Escherichia coli (ETEC) being the most common pathogen isolated. Although mild in most cases, the disease still leads to the loss of a significant part of a vacation or business trip. There is currently a lack of knowledge about the costs in relation to the benefits of vaccination against TD caused by ETEC, and the purposes of this study were to estimate and develop a cost-benefit analysis of vaccination using whole-cell/recombinant-B-subunit oral cholera vaccine.

METHODS

The consequences of the vaccination were identified and quantified in monetary terms. The cost-benefits for leisure and business travelers were assessed separately. The value of the travel was separated into the cost of the trip and of lost leisure time/business opportunities. A person with TD was in base case estimated to lose on average 3.5 days of a 7-day leisure trip and 2.5 days of a 4-day business trip. Results are presented for a Canadian traveler to endemic areas in year 2007 in US$.

RESULTS

The average cost of a TD event was estimated at $1,460 and $1,996 for leisure and business travelers, respectively. The net value of the vaccination, however, varied with the risk of the disease. Through extensive literature searches, an updated ETEC map illustrating the proportion of ETEC-caused TD was created.

CONCLUSIONS

The analysis indicated that vaccination would be considered cost-effective at incidence rates of ETEC-caused TD above about 13 and 9% for leisure and business travelers, respectively. It is, however, important to keep in mind that it is the value of the travel for the individual traveler that will decide if the vaccination provides good value for money.

Campylobacter jejuni-mediated disease pathogenesis: an update

Infection by Campylobacter jejuni is considered to be the most prevalent cause of bacterial-mediated diarrhoeal disease worldwide. Both in the developing and the developed world, young children remain most susceptible. Although disease is generally mild and self-limiting, severe post-infectious complications such as Gullain-Barré syndrome may occur. Despite the significant health burden caused by the organism, our current understanding of disease pathogenesis remains in its infancy. Elucidation of the genome sequences of many different C. jejuni strains in recent years has started to accelerate research in Campylobacter genetics, pathogenesis and host immunity in response to infection. Campylobacter jejuni is the first prokaryote shown to code for both O- and N-linked glycosylation systems, a feature that is likely to not only modulate bacterial virulence and survival, but also influence host-pathogen interactions and disease outcome. Here recent developments in C. jejuni research, with a particular focus on disease pathogenesis including early host immune responses, are highlighted.

[The management of travellers' diarrhoea]

Travellers' diarrhoea represents the most frequent health problem when travelling in developing countries. In most cases it is a self-limited disease. Nonetheless it can cause incapacitation and significant morbidity. It can become persistent in up to 3% of travellers who have suffered from acute diarrhoea in regions at high risk. This article discusses the investigations and the management of diarrhoea in returning travellers, preventive measures and its management during travel.

Sentinel surveillance for travellers' diarrhoea in primary care

Background

Travellers' diarrhoea is the most common health problem among international travellers and much of the burden falls on general practitioners. We assessed whether sentinel surveillance based in primary care could be used to monitor changes in the epidemiology of travellers' diarrhoea.

Methods

A sentinel surveillance scheme of 30 volunteer general practices distributed throughout Wales provides weekly reports of consultations for eight infectious diseases to the national Communicable Disease Surveillance Centre. Travellers' diarrhoea was introduced as a new reportable infection in July 2002.

Results

Between 1 July 2002 and 31 March 2005 there were 90 reports of travellers' diarrhoea. The mean annual consultation rate was 15.2 per 100,000 population (95% confidence interval: 12.2–18.7), with the highest rates in summer, in people aged 15–24 years, and in travellers to Southern Europe. A higher proportion of travellers than expected had visited destinations outside Europe and North America when compared to the proportion of all United Kingdom travellers visiting these destinations (38% vs. 11%; Chi² = 53.3, p < 0.0001).

Conclusion

Sentinel surveillance has the potential to monitor secular trends in travellers' diarrhoea and to help characterise population groups or travel destinations associated with higher risk.

In vitro antimicrobial activity of rifaximin against enteropathogens causing traveler's diarrhea

The in vitro activity of rifaximin against 84 diarrheagenic Escherichia coli and 11 Shigella sonnei causing traveler's diarrhea was evaluated. The MIC of rifaximin ranged between <0.007 and 32 mg/L; other agents tested had an MIC of >256 mg/L in most cases. The results showed the potential use of rifaximin to treat these infections.

The true burden and risk of cholera: implications for prevention and control

Cholera is a substantial health burden on the developing world and is endemic in Africa, Asia, South America, and Central America. The exact scale of the problem is uncertain because of limitations in existing surveillance systems, differences in reporting procedures, and failure to report cholera to WHO; official figures are likely to greatly underestimate the true prevalence of the disease. We have identified, through extensive literature searches, additional outbreaks of cholera to those reported to WHO, many of which originated from the Indian subcontinent and southeast Asia. Such underestimation of cholera can have important implications for decisions on provision of health interventions for indigenous populations, and on risk assessments for travellers. Furthermore, until recently, it has not been possible to implement public-health interventions in low-income countries to eliminate disease, and the prevention of cholera in travellers has been limited to restrictive guidelines. However, a vaccine against cholera is now available that has proven efficacy and tolerability in mass vaccination campaigns in low-income countries, and among travellers.

A report on a cluster of travelers' diarrhea among Cambodian students visiting Thailand

BACKGROUND

Travelers' diarrhea is an important gastrointestinal disorder in developing countries.

METHODS

A cluster of travelers' diarrhea among Cambodian students visiting Thailand is described in this article.

RESULTS

Nine cases of travelers' diarrhea were identified. These cases were among Cambodian students visiting Thailand under an exchange program. All presented with symptoms of diarrhea and nausea, and all improved within that day.

CONCLUSIONS

The prevention of gastrointestinal illness as well as recommendations for hygienic precautions for travelers who plan to visit tropical Asia, where the high prevalence of gastrointestinal disorder is documented, are important. In addition, a similar practice among local travelers within tropical Asia is also necessary.

Diagnostic value of endoscopy for the diagnosis of giardiasis and other intestinal diseases in patients with persistent diarrhea from tropical or subtropical areas

OBJECTIVE

Upper endoscopy has been suggested as a valuable tool in the diagnosis of giardiasis. The aim of this study was to compare two methods based on endoscopy, i.e. microscopy of duodenal fluid and histology, with a fluorescent-antibody assay for the detection of Giardia lamblia cysts in stool specimens. The role of endoscopy in the identification of other causes of chronic diarrhea acquired during travel abroad was also evaluated.

MATERIAL AND METHODS

Thirty-one patients (9 F, 22 M, median age 39 years, range 19-63 years) with persistent diarrhea after returning from tropical or subtropical areas agreed to undergo upper gastrointestinal endoscopy before and after treatment. Lower gastrointestinal endoscopy was subsequently performed. Three stool samples from each patient were examined using the direct fluorescent-antibody assay (DFA) for the detection of G. lamblia, and by routine methods for other protozoal and bacterial enteric pathogens. Each patient underwent upper endoscopy and biopsies and duodenal fluid samples were taken. In 12 patients a further lower endoscopy was performed.

RESULTS

In 16 patients G. lamblia was detected in stool samples by DFA (relative sensitivity: 100%). Histology of duodenal biopsies and microscopy of duodenal fluids allowed diagnosis of giardiasis to be made in only 8, and 3 patients, respectively (relative sensitivities: 21% and 44%). Besides giardiasis, upper endoscopic examination revealed an alternative diagnosis (tropical sprue), whereas six additional diagnoses were made by colonoscopy. In six patients the cause of chronic diarrhea remained unclear.

CONCLUSIONS

Compared to stool examinations using DFA, upper endoscopy is less sensitive for the diagnosis of giardiasis. In patients with negative stool examinations, lower endoscopy yields relevant diagnoses more often than upper endoscopy.

Imported infectious disease and purpose of travel, Switzerland

We evaluated the epidemiologic factors of patients seeking treatment for travel-associated illness from January 2004 through May 2005 at the University Hospital of Zurich. When comparing persons whose purpose of travel was visiting friends and relatives (VFR travelers; n = 121) with tourists and other travelers (n = 217), VFR travelers showed a distinct infectious disease and risk spectrum. VFR travelers were more likely to receive a diagnosis of malaria (adjusted odds ratio [OR] = 2.9, 95% confidence interval [CI] 1.2-7.3) or viral hepatitis (OR = 3.1, 95% CI 1.1-9) compared with other travelers but were less likely to seek pretravel advice (20% vs. 67%, p = 0.0001). However, proportionate rates of acute diarrhea were lower in VFR (173 vs. 364 per 1,000 ill returnees). Travel to sub-Saharan Africa contributed most to malaria in VFR travelers. In countries with large migrant populations, improved public health strategies are needed to reach VFR travelers.

Travelers' compliance to prophylactic measures and behavior during stay abroad: results of a retrospective study of subjects returning to a travel medicine center in Italy

BACKGROUND

Many sources of health advice are consulted by travelers, but in Europe, only 35% go to a travel clinic. Travel to countries outside Europe increases daily, and from 2001 to 2004, there was a marked increase in the number of travelers from the Florentine area crossing the borders (+18.0%), taking a plane (+81.4% of international travelers in Pisa airport), and applying to the Centre of Travel and Migration Medicine (CTMM) (+96%).

METHODS

An anonymous survey was carried out at CTMM among those travelers returning to complete vaccinations for which the first dose had been given before going abroad. The survey included questions on vaccination status, adherence to recommended antimalaria prophylaxis, occurrence of other health problems, and food and drink consumption.

RESULTS

The study population (which represents a "best case scenario") was composed of 1,237 subjects and had a very high compliance to the proposed questionnaire (95%). Approximately 55% of travelers took malaria chemoprophylactic measures, and 88% of them followed the indications given. Approximately 28% reported one or more secondary effects following antimalarial medication, and approximately 69% reported constant attention regarding safe consumption of food and drinks. Notwithstanding these measures, 236 cases of travelers' diarrhea were reported.

CONCLUSIONS

Our results are conditioned by the self-selection of the study population (those who seek advice are likely to follow it through). However, since no certainty exists about other sources of health advice for the remainder of the traveler population in our region, both the importance of counseling offered by travel clinics as well as the recommendation to the ever-increasing number of travelers to consult these clinics are stressed.

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.

Behaviors and perceptions of Japanese tourists affecting diarrheal illness and health care need assessment: A questionnaire study

Objectives

To measure the prevalence rate of, and determine the association between food and drink related behaviors and diarrheal illness among Japanese tourists, and assess their health care needs.

Methods

Eligible Japanese tourists (1,480) aged ≥15 years traveling in Chiangmai Province in the north, Ayutthaya Province in the center, Kanchanaburi Province in the west, Pattaya City in the east, and Krabi Province in the south of Thailand were enrolled in the study. Of these tourists, 1,318 consented to participate in this study and completed questionnaires in Japanese, giving a response rate of 89.1%.

Results

Among these Japanese tourists 21.3% had diarrheal illness, and of these tourists, 5.0% had classical travelers’ diarrhea (TD), 11.8% had mild TD, 3.3% had good food and drink related behaviors, and 75.4% had moderate level of perception of diarrhea related to drinking and eating. Multiple logistic regression analysis indicated three significant diarrheal illness predictors: large number of previous visits to Thailand, longer stay in Thailand, and the experience of visiting other countries. Furthermore, 56.9% suggested providing an adequate number of toilets at tourist destinations; 53.9% suggested providing a 24-hour emergency call facility for a public ambulance; and 51.9% suggested providing garbage bins and garbage disposal facilities at tourist destinations.

Conclusions

TD still affects experienced Japanese tourists who visit Thailand. Although the proportions of the good levels of food and drink related behaviors were low, there were indications that Japanese tourists perceived the risk of contracting TD.

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.

Oral cholera vaccines: use in clinical practice

Cholera continues to occur globally, particularly in sub-Saharan Africa and Asia. Oral cholera vaccines have been developed and have now been used for several years, primarily in traveller populations. The licensure in the European Union of a killed whole cell cholera vaccine combined with the recombinant B subunit of cholera toxin (rCTB-WC) has stimulated interest in protection against cholera. Because of the similarity between cholera toxin and the heat-labile toxin of Escherichia coli, a cause of travellers' diarrhoea, it has been proposed that the rCTB-WC vaccine may be used against travellers' diarrhoea. An analysis of trials of this vaccine against cholera (serotype O1) shows that for 4-6 months it will protect 61-86% of people living in cholera-endemic regions; lower levels of protection continue for 3 years. Protection wanes rapidly in young children. Because the risk of cholera for most travellers is extremely low, vaccination should be considered only for those working in relief or refugee settings or for those who will be travelling in cholera-epidemic areas and who will be unable to obtain prompt medical care. The vaccine can be expected to prevent 7% or less of cases of travellers' diarrhoea and should not be used for this purpose.

Adaptive immunity-dependent intestinal hypermotility contributes to host defense against Giardia spp

Humans infected with Giardia exhibit intestinal hypermotility, but the underlying mechanisms and functional significance are uncertain. Here we show in murine models of giardiasis that small-intestinal hypermotility occurs in a delayed fashion relative to peak parasite burden, is dependent on adaptive immune defenses, and contributes to giardial clearance.

Health risks at the Hajj

Annually, millions of Muslims embark on a religious pilgrimage called the "Hajj" to Mecca in Saudi Arabia. The mass migration during the Hajj is unparalleled in scale, and pilgrims face numerous health hazards. The extreme congestion of people and vehicles during this time amplifies health risks, such as those from infectious diseases, that vary each year. Since the Hajj is dictated by the lunar calendar, which is shorter than the Gregorian calendar, it presents public-health policy planners with a moving target, demanding constant preparedness. We review the communicable and non-communicable hazards that pilgrims face. With the rise in global travel, preventing disease transmission has become paramount to avoid the spread of infectious diseases, including SARS (severe acute respiratory syndrome), avian influenza, and haemorrhagic fever. We examine the response of clinicians, the Saudi Ministry of Health, and Hajj authorities to these unique problems, and list health recommendations for prospective pilgrims.

What's new in enteric infectious diseases at home and abroad

PURPOSE OF REVIEW

This review was designed to focus on the important research in the area of acute infectious diarrhea published within the past year. PubMed was reviewed for articles published in 2004 and 2005 relating to pathogen-specific diarrhea and for travelers' diarrhea to identify the newly published articles.

RECENT FINDINGS

New studies continue to show the importance of the diarrheagenic Escherichia coli as causes of acute and persistent diarrhea. Enteroaggregative E. coli has recently been shown to be an unrecognized cause of community-acquired diarrhea in infants in the USA. Genetic factors explain an increased susceptibility to travelers' diarrhea among international travelers. Also, poorly non-absorbed rifaximin (< 0.4%) was shown to be an effective drug when used prophylactically to prevent bacterial diarrhea during high risk travel.

SUMMARY

Studies will continue to define the etiology of diarrhea and to better understand the epidemiology and prevention of infectious diarrhea. Antibacterial resistance among enteric bacterial pathogens is a growing problem, leading to the search for newer antibacterial drugs. Diarrhea due to bacterial agents in international travelers can be prevented and treated successfully by antibacterial drugs. The nonabsorbed rifamycin drug, rifaximin, appears to be ideally suited to become the important new drug in prevention and treatment of travelers' diarrhea. Studies are underway to determine the value of the drug in preventing invasive forms of diarrhea during travel to Asia and in the prevention of the commonly occurring post-infectious irritable bowel syndrome.