Economic aspects of travelers' diarrhea

The Incidence and Risk Factors for Enterotoxigenic E. coli Diarrheal Disease in Children under Three Years Old in Lusaka, Zambia

This study aimed to estimate the incidence and risk factors for Enterotoxigenic Escherichia coli (ETEC) diarrhea. This was a prospective cohort study of children recruited in a household census. Children were enrolled if they were 36 months or below. A total of 6828 children were followed up passively for 12 months to detect episodes of ETEC diarrhea. Diarrheal stool samples were tested for ETEC using colony polymerase chain reaction (cPCR). Among the 6828 eligible children enrolled, a total of 1110 presented with at least one episode of diarrhea. The overall incidence of ETEC diarrhea was estimated as 2.47 (95% confidence interval (CI): 2.10-2.92) episodes per 100 child years. Children who were HIV-positive (adjusted Hazard ratio (aHR) = 2.14, 95% CI: 1.14 to 3.99; p = 0.017) and those whose source of drinking water was public tap/borehole/well (aHR = 2.45, 95% CI: 1.48 to 4.06; p < 0.002) were at increased risk of ETEC diarrhea. This study found that children whose mothers have at least senior secondary school education (aHR = 0.49, 95% CI: 0.29 to 0.83; p = 0.008) were at decreased risk of ETEC diarrhea. Our study emphasizes the need for integrated public health strategies focusing on water supply improvement, healthcare for persons living with HIV, and maternal education.

Estimating the Losses in Tourism Revenues due to Traveller's Diarrhoea

This study proposes a new method that more accurately estimates the losses in tourism revenues due to traveller's diarrhoea. The results show that the previous method underestimates these losses. For 2018 and 2019, the losses for developing countries were between US$2 billion and US$8 billion, under the new method.

Incidence Rate and Risk Factors Associated with Travelers' Diarrhea in International Travelers Departing from Utah, USA

Despite knowledge on the causes and prevention strategies for travelers' diarrhea (TD), it continues to be one of the most common illnesses experienced by U.S. international travelers. However, studies of risk factors associated with TD among U.S. travelers are limited. In this study, we aimed to determine the incidence rate of TD, the proportion of travelers who experience TD, and to identify risk factors associated with TD. In this cross-sectional study, we collected and analyzed data from anonymous posttravel questionnaires submitted by international travelers recruited during their pretravel visit at two travel clinics in Salt Lake City, Utah, from October 2016 to March 2020. Of 571 travelers who completed posttravel surveys, 484 (85%) answered the TD question, of which 111 (23%) reported TD, for an incidence rate of 1.1 episodes per 100 travel-days (95% confidence interval [CI]: 0.9-1.4). In a multivariable model, visiting Southeast Asian (odds ratio [OR]: 2.60; 95% CI: 1.45-4.72) and African (OR: 2.06; 95% CI: 1.09-3.93]) WHO regions, having 10 or more individuals in the group (OR: 3.91; 95% CI: 1.50-11.32]), longer trip duration (OR: 1.01; 95% CI: 1.00-1.02), visiting both urban and rural destinations (OR: 1.94; 95% CI: 1.01-3.90), and taking medications/supplements to prevent TD (OR: 2.74; 95% CI: 1.69-4.47) were statistically significantly associated with increased odds of reporting TD. TD continues to be common in international travelers from the United States. Our findings provide insights regarding travelers' behaviors regarding TD in international travelers from high-income countries and shows the need for additional research into prevention strategies for travelers' diarrhea.

What's new in travellers' diarrhoea: updates on epidemiology, diagnostics, treatment and long-term consequences

BACKGROUND

Travellers' diarrhoea (TD) is the most common clinical syndrome affecting travellers. This narrative review summarizes key discoveries reported in the last two years related to TD and suggests areas for future research.

METHODS

A PubMed literature search was conducted for novel data in TD research published between 12 January 2018 and 12 January 2020. Inclusion was based on contribution to epidemiology, aetiology, diagnostics, management and long-term consequences and relevance to public health, discovery and clinical practice.

RESULTS

The initial literature search yielded 118 articles. We retrieved 72 and reviewed 31 articles for inclusion. The findings support our understanding that TD incidence varies by traveller group and environment with students and military-travel remaining moderately high risk, and control of food and water in mass gathering events remain an important goal. The growth of culture-independent testing has led to a continued detection of previously known pathogens, but also an increased detection frequency of norovirus. Another consequence is the increase in multi-pathogen infections, which require consideration of clinical, epidemiological and diagnostic data. Fluoroquinolone resistant rates continue to rise. New data on non-absorbable antibiotics continue to emerge, offering a potential alternative to current recommendations (azithromycin and fluoroquinolones), but are not recommended for febrile diarrhoea or dysentery or regions/itineraries where invasive pathogens are likely to cause illness. Recent studies investigated the interaction of the microbiome in TD prevention and consequences, and while discriminating features were identified, much uncertainty remains. The prevalence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) acquisition and carriage is increasing. Finally, continued research documents the post-infectious consequences, whereas mechanisms of reactive arthritis and post-infectious IBS necessitate further investigation.

CONCLUSIONS

Globally, TD remains an important travel health issue and advances in our understanding continue. More research is needed to mitigate risk factors where possible and develop risk-based management strategies to reduce antibiotic usage and its attendant consequences.

Community Causes of Death in the Central Region of Ghana, the Missing Piece in Mortality Data

Objective. Mortality data from hospitals in Ghana suggest a changing mortality trend with noncommunicable diseases (cardiovascular disorders) replacing communicable diseases as the leading cause of death. Our objective was to find out the causes of deaths in the communities of the Central Region of Ghana and raise awareness of these causes of deaths while highlighting the differences that exist between data obtained from the community and that obtained from the hospital. Method. Mortality data from Coroner’s autopsies mostly provide data about the causes of deaths in the community (out of hospital). A retrospective descriptive study of Coroner’s autopsy data at the Cape Coast Teaching Hospital was carried out over a six-year period. The various causes of death were categorized according to broad headings (accidents/injuries/poisoning, cardiovascular, infections, metabolic, neoplasms, and others). Results. A total of 1187 autopsies were reviewed of which 990 (83.4%) were Coroner’s cases. Of these Coroner’s cases, 719 (72.6%) were male and 271 (27.4%) were female. 521 (52.6%) of victims were young adults (18–44 years), and majority of deaths were unnatural (due to accidents, injuries, and poisoning) (64.1%), followed by the general category of others (15.3%). Cardiovascular deaths (6.6%) were fourth after infections (9.8%). In the leading category, most deaths were due to road traffic accidents (50.4%) as occupants of vehicles and motorcycles (28.7%) and as pedestrians (21.7%). Deaths due to road traffic accidents were followed by deaths due to drowning (14.96%). Conclusion. Although noncommunicable diseases are still the leading causes of death outside the hospital, most of the deaths are due to road traffic accidents and drowning. This is at variance with hospital data that suggest that the leading noncommunicable diseases are cardiovascular disorders and cancer. Again, like data derived from hospitals, infections remain a major cause of death in the Central Region of Ghana. Studies combining the causes of death derived from Coroner’s autopsies and communities and from medical certificates of cause of death will present a better picture of the leading causes of death in the Central Region and reveal the true nature of noncommunicable diseases that currently form our largest disease burden.

Impact of alcohol-based hand-gel sanitizer and hand hygiene advice on travellers' diarrhoea and colonization with extended-spectrum beta-lactamase-producing Enterobacteriaceae: A randomised, controlled trial

BACKGROUND

Travellers' diarrhoea (TD) is the most common health problem in international travellers. Besides being bothersome for the individual and a considerable economic burden for the public, TD is also known to be associated with becoming colonized with extended-spectrum β-lactamase (ESBL)-producing Enterobacteriacea. Despite the high frequency of TD cases, easy and effective preventive measures are lacking. The aim of this study was to assess the impact of using hand gel sanitizer on the incidence of TD and colonization with ESBL-producing Enterobacteriaceae.

METHOD

A multicentre randomized intervention trial studying the effect of hand gel sanitizer on the incidence of TD and colonization with ESBL-producing Enterobacteriaceae in travellers to Southeast Asia was performed.

RESULTS

The intention to treat analysis showed a reduction in the incidence of WHO TD in the intervention group (OR 0.54 (95% CI 0.30-0.97), p = 0.04). No effect was seen or the incidence of becoming colonized with ESBL-producing Enterobacteriaceae.

CONCLUSION

Using hand gel sanitizer might have a protective effect on the occurrence of TD. Based on the current data, education on the proper use appears to play a key role for its effectiveness.

Nonaplex PCR using Cliffhanger primers to identify diarrhoeagenic Escherichia coli from crude lysates of human faecal samples

Sensitive, probe-based detection of multiple DNA targets is limited by the competitive reannealing of the antiparallel duplex DNA helix with the complementary DNA strand. To address this, we developed Cliffhanger primers, which create single-stranded DNA overhangs on PCR amplicons while simultaneously increasing the multiplex PCR efficacy and allowing PCR amplification using crude lysates of human faecal samples. A multiplex PCR that targeted eight genes from diarrhoeagenic Escherichia coli plus an internal control was performed and compared to a routine method that consisted of culture followed by multiplex PCR with fragment length separation. A total of 2515 clinical faecal samples from patients with diarrhoea were tested using both methods, and there was a significant increase in clinical sensitivity and negative predictive value with the Cliffhanger method for seven out of eight genes. All Cliffhanger-only positive samples were confirmed by Sanger sequencing of the PCR amplicon. Notably, the Cliffhanger method reduced the total sample turn-around time in the laboratory from 20 hours to 6 hours. Hence, use of Cliffhanger primers increased assay robustness, decreased turn-around time and increased PCR efficacy. This increased the overall clinical sensitivity without the loss of specificity for a heavily multiplexed PCR assay.

Previous exposure in a high-risk area for travellers' diarrhoea within the past year is associated with a significant protective effect for travellers' diarrhoea: a prospective observational cohort study in travellers to South Asia

BACKGROUND

Travellers' diarrhoea is the most common health problem in travellers. Depending on the region visited, up to 40% of travellers develop diarrhoea during a 2-week trip. The aim of this study was to assess risk factors for TD among travellers to the Indian subcontinent.

METHODS

An observational prospective multicentre cohort study investigated travellers to the Indian subcontinent. Participants completed questionnaires assessing the incidence of travellers' diarrhoea and identifying potential risk factors. Covariates were assessed univariately, followed by a multivariate regression.

RESULTS

Two-hundred and twenty-six travellers were enrolled into the study, 178 filled in both pre- and post-travel questionnaires. Overall, the attack rate of travellers' diarrhoea was 38.2%. Travel destination is a key risk factor for the occurrence of TD. Travelling to India or Nepal vs Bhutan is associated with an increased risk for TD (OR 6.68 and 6.62, respectively). A length of stay of more than 3 weeks compared to less than 2 weeks is also associated with a significantly increased risk (OR 5.45). Having stayed in a high-risk area for travellers' diarrhoea within the past year before the current trip is associated with a significantly decreased risk (OR 0.19). No association was found between consumption of high risk food (i.e. tap water, ice cream, raw meat and hamburgers) and travellers' diarrhoea.

CONCLUSION

Travellers' diarrhoea is a frequent problem in travellers to the Indian subcontinent. Previous exposure in a high-risk area for travellers' diarrhoea within the past year appears to have a significant protective effect. Furthermore, an association between the occurrence of travellers' diarrhoea and travel destination and length of stay, respectively, was observed. Consumption of risk food did not confer a TD risk in our study.

Bioactive Immune Components of Anti-Diarrheagenic Enterotoxigenic Escherichia coli Hyperimmune Bovine Colostrum Products

Diarrhea is a common illness among travelers to resource-limited countries, the most prevalent attributable agent being enterotoxigenic Escherichia coli (ETEC). At this time, there are no vaccines licensed specifically for the prevention of ETEC-induced traveler's diarrhea (TD), and this has propelled investigation of alternative preventive methods. Colostrum, the first milk expressed after birthing, is rich in immunoglobulins and innate immune components for protection of newborns against infectious agents. Hyperimmune bovine colostrum (HBC) produced by immunization of cows during gestation (and containing high levels of specific antibodies) is a practical and effective prophylactic tool against gastrointestinal illnesses. A commercial HBC product, Travelan, is available for prevention of ETEC-induced diarrhea. Despite its demonstrated clinical efficacy, the underlying immune components and antimicrobial activity that contribute to protection remain undefined. We investigated innate and adaptive immune components of several commercial HBC products formulated to reduce the risk of ETEC-induced diarrhea, including Travelan and IMM-124E, a newer product that has broader gastrointestinal health benefits. The immune components measured included total and ETEC-specific IgG, total IgA, cytokines, growth factors, and lactoferrin. HBC products contained high levels of IgG specific for multiple ETEC antigens, including O-polysaccharide 78 and colonization factor antigen I (CFA/I) present in the administered vaccines. Antimicrobial activity was measured in vitro using novel functional assays. HBC greatly reduced ETEC motility in soft agar and exhibited bactericidal activity in the presence of complement. We have identified immune components and antimicrobial activity potentially involved in the prevention of ETEC infection by HBC in vivo.

Guidelines for the prevention and treatment of travelers' diarrhea: a graded expert panel report

BACKGROUND

: Travelers' diarrhea causes significant morbidity including some sequelae, lost travel time and opportunity cost to both travelers and countries receiving travelers. Effective prevention and treatment are needed to reduce these negative impacts.

METHODS

: This critical appraisal of the literature and expert consensus guideline development effort asked several key questions related to antibiotic and non-antibiotic prophylaxis and treatment, utility of available diagnostics, impact of multi-drug resistant (MDR) colonization associated with travel and travelers' diarrhea, and how our understanding of the gastrointestinal microbiome should influence current practice and future research. Studies related to these key clinical areas were assessed for relevance and quality. Based on this critical appraisal, guidelines were developed and voted on using current standards for clinical guideline development methodology.

RESULTS

: New definitions for severity of travelers' diarrhea were developed. A total of 20 graded recommendations on the topics of prophylaxis, diagnosis, therapy and follow-up were developed. In addition, three non-graded consensus-based statements were adopted.

CONCLUSIONS

: Prevention and treatment of travelers' diarrhea requires action at the provider, traveler and research community levels. Strong evidence supports the effectiveness of antimicrobial therapy in most cases of moderate to severe travelers' diarrhea, while either increasing intake of fluids only or loperamide or bismuth subsalicylate may suffice for most cases of mild diarrhea. Further studies are needed to address knowledge gaps regarding optimal therapies, the individual, community and global health risks of MDR acquisition, manipulation of the microbiome in prevention and treatment and the utility of laboratory testing in returning travelers with persistent diarrhea.

Epidemiology of travellers' diarrhea

BACKGROUND

Travellers' diarrhea (TD) continues to be the most frequent health problem in travellers with destinations in lower income parts of the world as compared with where they reside, even if that risk has slightly decreased.

METHODS

A systematic review was published 18 months ago; now PubMed was searched for more recent publications relating to travel, diarrhea, epidemiology, incidence, risk.

RESULTS

A trend to decreasing incidence rates have been noted in this as compared with the last century, but TD remains frequent. The clinical picture varies from a trivial ailment to severe with subsequent hospitalization. Of great concern are long-term sequelae, particularly post-infectious irritable bowel syndrome. The most important risk factors are the destination and duration of exposure among the environmental factors, whereas the age is the most relevant host factor.

CONCLUSIONS

Even if improved hygienic conditions in low-income countries often visited by travellers have resulted in slightly diminished incidence rates of TD, this remains a frequent health problem. Visitors to such destinations must be informed about that health risk and it is beneficial to equip them with instructions and a travel kit to enable them to some extent self-manage TD occurring abroad.

Commercializing diarrhea vaccines for travelers

Continued growth in international travel and forecasts for a great increase in the number of people who travel from industrialized to emerging and developing countries make it necessary to develop and improve the capacity to provide health protection to travelers. Measures available to prevent some diseases include a currently limited number of marketed vaccines which represent extremely useful tools to protect travelers. Travelers very often experience diarrheal and gastrointestinal diseases for which some vaccines are available. Use of these vaccines should be evaluated based on traveler and travel destination and characteristics. Vaccines available include those against cholera, typhoid fever, hepatitis A, hepatitis E (only available in China), and rotavirus. The aim of this review is to provide an updated summary about each of the abovementioned vaccines that may be useful for making decisions regarding their use and assessing their indications in recommendations for travelers.

Health hazards and medical treatment of volunteers aged 18-30 years working in international social projects of non-governmental organizations (NGO)

The specific health risk profile and diversity of treatments sought by young volunteers participating in international social projects should differ from those of their older colleagues. In the absence of any data to identify whether this was correct, a retrospective analysis was performed using a standardized questionnaire. Questions included what diseases occurred, and details of the frequency and types of treatment sought during their stay - (e.g. self-treatment, medical/dental intervention, or local healer). The 153 participants were aged 18-30 years and worked in a non-governmental organization for >6 months. The participants were: 53% female, mean age 20 years, and mean duration of stay was 11.2 months. Their NGO placement abroad was in Latin America 65.4%, 14.4% in Africa, and 9.8% in Asia. 83% of the young volunteers had received some advice regarding travel medicine before their departure. However, they suffered from more injuries compared to private travellers, and febrile infections were more common when compared to older studies. 21.2% suffered from dental problems and 50% of them sought medical treatment. This study highlights a previously unreported higher risk profile of specific health problems occurring in young NGO volunteers, including some potentially life-threatening diagnoses that differed from their older colleagues and normal travellers. It is recommended that young volunteers should receive age specific, comprehensive pre-departure training in health and safety, first aid, and management of common health problems. A medical check-up upon returning home should be mandatory. The provision of a basic first aid kit to each volunteer before departure is also recommended.

Effectiveness of the WC/rBS oral cholera vaccine in the prevention of traveler's diarrhea: a prospective cohort study

OBJECTIVE

Traveler's diarrhea (TD) is the most frequent disease among people from industrialized countries who travel to less developed ones, especially sub-Saharan Africa, Southern Asia and South America. The most common bacteria causing TD is enterotoxigenic Escherichia coli (ETEC). The WC/rBS cholera vaccine (Dukoral) has been shown to induce cross-protection against ETEC by means of the B subunit of the cholera toxin. The aim of the study was to evaluate the effectiveness of the WC/rBS cholera vaccine in preventing TD.

METHODS

Between May 1 and September 30 (2007), people seeking pre-travel advice in ten Spanish international vaccination centers were included in a prospective cohort study of travelers to cholera risk countries. The incidence rates of TD were adjusted for variables whose frequencies were statistically different (entry point 0.10) between the vaccinated and non-vaccinated cohorts.

FINDINGS

The vaccinated cohort (n = 544 travelers) included people vaccinated with the WC/rBS cholera vaccine, and the non-vaccinated cohort (n = 530 travelers) by people not vaccinated. The cumulative incidence rate of TD was 1.69 in vaccinated and 2.14 in non-vaccinated subjects. The adjusted relative risk of TD in vaccinated travelers was 0.72 (95% CI: 0.58-0.88) and the adjusted vaccination effectiveness was 28% (95% CI: 12-42).

CONCLUSIONS

The WC/rBS cholera vaccine prevents TD in 2 out of 7 travelers (preventive fraction: 28%). The number needed to vaccinate (NNV) to prevent 1 case of TD is 10.

Clinical implications of enteroadherent Escherichia coli

Pathogenic Escherichia coli that colonize the small intestine primarily cause gastrointestinal illness in infants and travelers. The main categories of pathogenic E. coli that colonize the epithelial lining of the small intestine are enterotoxigenic E. coli, enteropathogenic E. coli, and enteroaggregative E. coli. These organisms accomplish their pathogenic process by a complex, coordinated multistage strategy, including nonintimate adherence mediated by various adhesins. These so called "enteroadherent E. coli" categories subsequently produce toxins or effector proteins that are either secreted to the milieu or injected to the host cell. Finally, destruction of the intestinal microvilli results from the intimate adherence or the toxic effect exerted over the epithelia, resulting in water secretion and diarrhea. In this review, we summarize the current state of knowledge regarding these enteroadherent E. coli strains and the present clinical understanding of how these organisms colonize the human intestine and cause disease.

The oral, live attenuated enterotoxigenic Escherichia coli vaccine ACE527 reduces the incidence and severity of diarrhea in a human challenge model of diarrheal disease

An oral, live attenuated, three-strain recombinant bacterial vaccine, ACE527, was demonstrated to generate strong immune responses to colonization factor and toxin antigens of enterotoxigenic Escherichia coli (ETEC) in human volunteers. The vaccine was safe and well tolerated at doses of up to 10(11) CFU, administered in each of two doses given 21 days apart. These observations have now been extended in a phase 2b study with a total of 70 subjects. Fifty-six of these subjects were challenged 28 days after the second dose of vaccine with the highly virulent ETEC strain H10407 to obtain preliminary indicators of efficacy against disease and to support further development of the vaccine for both travelers and infants in countries where ETEC is endemic. The vaccine had a significant impact on intestinal colonization by the challenge strain, as measured by quantitative fecal culture 2 days after challenge, demonstrating the induction of a functional immune response to the CFA/I antigen. The incidence and severity of diarrhea were also reduced in vaccinees as measured by a number of secondary and ad hoc endpoints, although the 27% reduction seen in the primary endpoint, moderate to severe diarrhea, was not statistically significant. Together, these observations support the hypothesis that the ACE527 vaccine has a dual mode of action, targeting both colonization factors and the heat-labile enterotoxin (LT), and suggest that it should be further developed for more advanced trials to evaluate its impact on the burden of ETEC disease in field settings.

Chronic gastrointestinal consequences of acute infectious diarrhea: evolving concepts in epidemiology and pathogenesis

Acute infectious diarrhea is a frequent occurrence both in the developing world, where it results in considerable mortality, and in developed countries, where it accounts for a significant number of health visits, hospitalizations, and medical and non-medical losses. Recent evidence in basic, clinical, and epidemiological science domains has emerged that suggest that the burden caused by these infections is not limited to the acute illness, but may result in triggering or contributing to the pathogenesis of a number of chronic health problems. This review considers the breadth of this information for the purpose of consolidating what is currently known, identifying gaps in knowledge, and describing future directions and policy implications related to the chronic consequences of acute infectious diarrhea. A unifying hypothesis of this review is that infections may trigger a number of long-lasting changes in gut physiology and immunity that can increase the risk to a variety of chronic gastrointestinal diseases, particularly in genetically susceptible individuals.

Advances in the treatment of travelers' diarrhea

Diarrhea is the most common complaint reported by travelers from industrialized countries visiting developing nations. High-risk areas for travelers' diarrhea (TD) include South Asia, Sub-Saharan Africa, and Latin America, while moderate-risk areas include Southeast Asia, Middle East, Oceania and the Caribbean. Bacterial pathogens are the major cause of TD. Recent advances in the therapy for diarrhea include a better understanding of the potential benefit of symptomatic and antimicrobial therapy. The mainstay of treatment includes antibacterial therapy with one of three drugs, a fluoroquinolone, rifaximin, or azithromycin. Probiotics have been used in preliminary studies for both treatment and prevention of TD, but more studies are needed with these biologic agents. The aim of this review is to identify the recent advances in the therapy of TD and to provide recommendations for treatment during international travel.

A combination vaccine consisting of three live attenuated enterotoxigenic Escherichia coli strains expressing a range of colonization factors and heat-labile toxin subunit B is well tolerated and immunogenic in a placebo-controlled double-blind phase I trial in healthy adults

Immune responses against colonization factors (CFs) and the nontoxic B component of the enterotoxigenic Escherichia coli (ETEC) heat-labile toxin (LTB) are considered to be important for immunity against diarrhea caused by ETEC. Individual live attenuated ETEC derivatives that have had their toxin genes removed and whose aroC, ompC, and ompF genes are deleted have shown promise as vaccines against ETEC. The development of such strains has culminated in the testing of a three-strain-combination live attenuated vaccine known as ACE527, comprised of strains ACAM2025 expressing colonization factor antigen I (CFA/I) and LTB; ACAM2022, expressing CS5, CS6, and LTB; and ACAM2027, expressing CS1, CS2, CS3, and LTB. The recombinant CF and LTB genes expressed in the three strains were inserted into the bacterial chromosome to ensure their stable inheritance and expression without the requirement for any selection. ACE527 has been tested in a randomized placebo-controlled, double-blind, phase I safety and immunogenicity study in healthy adult volunteers and proved to be well tolerated and immunogenic at dose levels of 10(10) and 10(11) total CFU. There was no indication of strain interference on the basis of fecal shedding patterns, with all three being detected in the feces of 50% and 83% of low- and high-dose vaccine recipients, respectively. Similarly, strong immune responses to LTB and to CFs expressed on all three constituent strains were induced, with at least 50% of subjects in the high-dose group responding to LTB, CFA/I, CS3, and CS6.

Vaccination strategies to combat an infectious globe: oral cholera vaccines

Cholera is a substantial health burden in many countries in Africa and Asia, where it is endemic. It is as well responsible for ongoing epidemics in sub-Saharan Africa which are becoming greater in terms of frequency, extension, and duration. Given the availability of two oral cholera vaccines and the new data on their efficacy, field effectiveness, feasibility, and acceptance in cholera-affected populations and in travelers, these vaccines should be used in endemic areas, in travelers for these areas and should be considered in areas at risk for outbreaks. The two vaccines currently available in worldwide are: (1) The killed oral vaccine (Dukoral, licensed by SBL–Sweden to Crucell–Holland) is recommended since 1999 by WHO and consists of a mixture of four preparations of heat or formalin killed whole cell Vibrio cholera O1 (Inaba and Ogaba serotypes, and classical and El Tor biotypes) that are then added with purified recombinant cholera toxin (CT) B subunit. Because CT cross-reacts with Escherichia coli LT the vaccine also provides short-term protection against ETEC (enterotoxigenic E. coli) which is of added benefit for travelers. It is available in more than 60 countries. (2) A bivalent O1 and O139 whole cell oral vaccine without CT B subunit (Shanchol) has been lately developed in Vietnam (licensed by VaBiotech–Viet Nam to Shantha Biotechnics–India. It is available in India and Indonesia. A structured search of papers in PubMed and reports on cholera vaccines by WHO and CDC, as well as critical reading and synthesis of the information was accomplished. Inclusion criteria were defined according to reports quality and relevance.

Incidence and impact of travelers' diarrhea among foreign backpackers in Southeast Asia: a result from Khao San road, Bangkok

BACKGROUND

Travelers' diarrhea is the most common disease reported among travelers visiting developing countries, including Southeast Asia, a region visited by large numbers of backpackers each year. Currently, the knowledge of travelers' diarrhea among this group is limited. This study aimed to determine the incidence and impact of travelers' diarrhea in this group.

METHOD

Foreign backpackers in Khao San road, Bangkok, Thailand, were invited to fill out a study questionnaire, in which they were queried about their demographic background, travel characteristics, pretravel preparations and actual practices related to the risk of travelers' diarrhea. For backpackers who had experienced diarrhea, the details and impact of each diarrheal episode were also assessed.

RESULTS

In the period April to May 2009, 404 completed questionnaires were collected and analyzed. Sixty percent of participants were male; overall, the median age was 26 years. Nearly all backpackers (96.8%) came from developed countries. Their main reason for travel was tourism (88%). The median stay was 30 days. More than half of the backpackers (56%) carried some antidiarrheal medication. Antimotility drugs were the most common medications carried by backpackers, followed by oral rehydration salts (ORS), and antibiotics. Their practices were far from ideal; 93.9% had bought food from street vendors, 92.5% had drunk beverages with ice-cubes, and 33.8% had eaten leftover food from a previous meal. In this study, 30.7% (124/404) of backpackers had experienced diarrhea during their trip. Most diarrhea cases (88%) were mild and recovered spontaneously. However, 8.8% of cases required a visit to a doctor, and 3.2% needed hospitalization. Longer duration of stay and drinking beverages with ice-cubes were associated with higher risk of diarrhea.

CONCLUSIONS

About one third of the foreign backpackers in Southeast Asia had experienced diarrhea during their trip. Their current practices related to the risk of travelers' diarrhea were inadequate and should be improved.

Effectiveness and economic analysis of the whole cell/recombinant B subunit (WC/rbs) inactivated oral cholera vaccine in the prevention of traveller's diarrhoea

BACKGROUND

Nowadays there is a debate about the indication of the oral whole-cell/recombinant B-subunit cholera vaccine (WC/rBS) in traveller's diarrhoea. However, a cost-benefit analysis based on real data has not been published.

METHODS

A cost-effectiveness and cost-benefit study of the oral cholera vaccine (WC/rBS), Dukoral for the prevention of traveller's diarrhoea (TD) was performed in subjects travelling to cholera risk areas. The effectiveness of WC/rBS vaccine in the prevention of TD was analyzed in 362 travellers attending two International Vaccination Centres in Spain between May and September 2005.

RESULTS

The overall vaccine efficacy against TD was 42,6%. Direct healthcare-related costs as well as indirect costs (lost vacation days) subsequent to the disease were considered. Preventive vaccination against TD resulted in a mean saving of 79.26 euro per traveller.

CONCLUSION

According to the cost-benefit analysis performed, the recommendation for WC/rBS vaccination in subjects travelling to zones at risk of TD is beneficial for the traveller, regardless of trip duration and visited continent.

Epidemiology of travelers' diarrhea in Thailand

BACKGROUND

Current data on risk of travelers' diarrhea (TD) among visitors to Thailand largely comes from US military personnel, Peace Corps volunteers, or expatriates. We performed a 14-month systematic study of the incidence rate and characteristics of TD and a smaller study of etiology of the disease among visitors to Phuket and Chiang Mai.

METHODS

One randomly selected day each week from August 2005 until October 2006, data were collected from foreign tourists departing from airports serving Phuket and Chiang Mai. A separate subgroup of subjects with TD acquired in Phuket were invited to submit a stool sample for enteropathogens.

RESULTS

Based on 22,401 completed questionnaires, the attack rate for TD was highest among residents from Australia or New Zealand (16%), while those from the United States and Europe had attack rates of 7% to 8%. Independent risk factors for the development of TD were eating outside the hotel and eating meat. In contrast, a history of drinking tap water and consuming ice cream were protective. In 56 subjects studied for etiology, Aeromonas spp were found in 8 subjects (14%), enterotoxigenic Escherichia coli (ETEC) or Vibrio spp each was found in 7 (13%) with O1 V. cholera (cholera) seen in one, mixed pathogens were found in 3 (5%), with no pathogen being detected in 33 (59%).

CONCLUSIONS

Phuket and Chiang Mai should not be considered high-risk destinations for development of TD among US and European travelers to Thailand. In the study, Aeromonas, ETEC, and Vibrio spp were the most frequent enteropathogens identified.

Management of travelers' diarrhea by local physicians in tropical and subtropical countries--a questionnaire survey

BACKGROUND

There is an ongoing debate as to whether patients with travelers' diarrhea (TD) should self-medicate with a travel kit in developing countries or whether they should consult local doctors. Thus, we have analyzed TD management conducted by local health professionals.

METHODS

Practicing physicians recommended to tourists in Goa (India), Mombasa (Kenya), and Phuket (Thailand) were invited to participate in a cross-sectional questionnaire survey. Three TD case descriptions were presented, and suggested diagnostic and therapeutic procedures were analyzed.

RESULTS

In each of the three locations, approximately 20 physicians (59 in total, response rate 95%) completed the questionnaires. Oral rehydration was proposed by more than 80% of the physicians for mild cases of TD and for TD with vomiting, while 73% of them would have treated febrile TD patients orally and 17% would have used intravenous (IV) fluids. Antimicrobials, primarily fluoroquinolones, would have been prescribed for 61, 73, and 95%, respectively, of these three cases. Cephalosporins, aminoglycosides (usually IV gentamicin), IV amoxicillin, and once co-trimoxazole were recommended. Many medical doctors added nitroimidazole to the antibiotic therapy. Multiple symptomatic drugs would have been prescribed. The rate of invasive procedures (infusions, injections, and diagnostic venipuncture) would have ranged from 20% to 86% in the scenarios of the different patients. Mainly practitioners who owned a clinic would have hospitalized patients with TD.

CONCLUSIONS

Many physicians in destination countries treat TD patients similarly to the treatments prescribed in the "Western world." A minority uses obsolete antimicrobials. Polypharmacy and the high rate of invasive procedures with a theoretical risk of nosocomial infection are of concern. Training initiatives for both local physicians and travelers might be beneficial, and the guidelines should be based on internationally accepted expert advice.