Epidemiology of Travelers— Diarrhea: Details of a Global Survey

Background Recent epidemiologic data on travelers— diarrhea (TD) are essential for the evaluation of conventional and future prophylactic and therapeutic measures.
Methods To determine the epidemiology, including risk factors, impact and quality-of-life evaluation of TD, a cross-sectional survey was conducted over 12 months at the airports of Mombasa (Kenya), Goa (India), Montego Bay (Jamaica) and Fortaleza (Brazil) by distributing questionnaires to visitors just prior to their flying home. The study period was March 1996 to July 1998.
Results Overall, 73,630 short-term visitors completed a questionnaire. The total diarrhea attack rate varied between a high of 54.6% in Mombasa and a low of 13.6% in Fortaleza, but only between 31.5% and 5.4% of all travelers had classic TD. The 14-day incidence rates varied between 19.5% and 65.7%. Few travelers meticulously avoided potentially dangerous food items, although in India and Kenya most travelers avoided those considered most dangerous. Risk factors were stays exceeding 1 week, age between 15 and 30 years, and residence in the UK. The impact, measured as incapacity or quality-of-life scores, was very considerable.
Conclusions TD continues to affect vacationers and business travelers as frequently as it did some 20 years ago. Compliance with recommendations to reduce exposure to pathogens by avoiding dangerous food items is poor among travelers from all countries. Implementation of food safety education programs may be difficult to achieve.     

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.     

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.     

Mefloquine in the Prophylaxis of P. Falciparum Malaria

Background: The objectives of this study were (1) to compare the efficacy of Lariam (mefloquine) with that of Fansimef (mefloquine, sulfadoxine, and pyrimethamine), Fansidar (sulfadoxine and pyrimethamine), chloroquine, and placebo in suppressing asexual parasitemia in semi-immune persons living in an area endemic for Plasmodium falciparum malaria; and (2) to compare the tolerance of these drugs when taken over a prolonged period of time.
Method: A randomized double-blind comparative placebo-controlled study was undertaken in the village of Biasso, 60 km from Abidjan in the southern part of the Ivory Coast, a region where P. falciparum malaria is endemic. Four hundred and ninety nine male volunteers (five parallel groups), who were inhabitants of Biasso, were involved. The main outcome measures concerned the incidence of malaria breakthroughs (acute malaria attacks) and the incidence of parasitemia.
Results: Within this strictly defined epidemiologic context, prophylaxis, taken once weekly, proved to be fully protective (parasitic index: 0) in the Lariam, Fansidar, and Fansimef groups throughout the whole study period. Prophylaxis with chloroquine proved incompletely protective (parasitic index: 2.5) The most frequent side effects were pruritus (5.6%), diarrhea (1.2%) and headache (0.06%). No significant differences in the incidence of side effects in each group (chi-square test) was observed. All side effects were transient and judged to be mild by the investigators.
Conclusions: Excellent efficacy was observed in the prophylaxis of P. falciparum malaria with Lariam, Fansidar, and Fansimef as compared to the partial protection provided by chloroquine. Safety and tolerance were comparable in all groups during the whole period of observation (5 months).     

Epidemiology of travelers' diarrhea: details of a global survey

BACKGROUND: Recent epidemiologic data on travelers' diarrhea (TD) are essential for the evaluation of conventional and future prophylactic and therapeutic measures. METHODS: To determine the epidemiology, including risk factors, impact and quality-of-life evaluation of TD, a cross-sectional survey was conducted over 12 months at the airports of Mombasa (Kenya), Goa (India), Montego Bay (Jamaica) and Fortaleza (Brazil) by distributing questionnaires to visitors just prior to their flying home. The study period was March 1996 to July 1998. RESULTS: Overall, 73,630 short-term visitors completed a questionnaire. The total diarrhea attack rate varied between a high of 54.6% in Mombasa and a low of 13.6% in Fortaleza, but only between 31.5% and 5.4% of all travelers had classic TD. The 14-day incidence rates varied between 19.5% and 65.7%. Few travelers meticulously avoided potentially dangerous food items, although in India and Kenya most travelers avoided those considered most dangerous. Risk factors were stays exceeding 1 week, age between 15 and 30 years, and residence in the UK. The impact, measured as incapacity or quality-of-life scores, was very considerable. CONCLUSIONS: TD continues to affect vacationers and business travelers as frequently as it did some 20 years ago. Compliance with recommendations to reduce exposure to pathogens by avoiding dangerous food items is poor among travelers from all countries. Implementation of food safety education programs may be difficult to achieve.     

Interventions to Prevent and Control Food-Borne Diseases Associated with a Reduction in Traveler—s Diarrhea in Tourists to Jamaica

Background In 1996 a study found that approximately one in four tourists to Jamaica were affected with traveler—s diarrhea (TD) during their stay. That year the Ministry of Health initiated a program for the prevention and control of TD. The aim of this ongoing program was to reduce attack rates of TD from 25% to 12% over a 5-year period by improving the environmental health and food safety standards of hotels.
Methods Hotel-based surveillance procedures for TD were implemented in sentinel hotels in Negril and Montego Bay in 1996, Ocho Rios in 1997, and Kingston in 1999. A structured program provided training and technical assistance to nurses, food and beverage staff, and environmental sanitation personnel in the implementation of Hazard Analysis Critical Control Point principles for monitoring food safety standards. The impact of interventions on TD was assessed in a survey of tourists departing from the international airport in Montego Bay in 1997–1998 and from the international airport in Kingston in 1999–2000. The impact of the training and technical assistance program on food safety standards and practices was assessed in hotels in Ocho Rios as of 1998 and in Kingston from 1999.
Results At the end of May 2002, TD incidence rates were 72% lower than in 1996, when the Ministry of Health initiated its program for the prevention and control of TD. Both hotel surveillance data and airport surveillance data suggest that the vast majority of travelers to Kingston and southern regions are not afflicted with TD during their stay. The training and technical assistance program improved compliance to food safety standards over time.
Conclusion Interventions to prevent and control TD in visitors to Jamaica are positively associated with a reduction in TD in the visitor population and improvements in food safety standards and practices in hotels.     

Impact of Travel-Related Health Impairments

Background: Few recent data exist on the impact of travel-related health problems.
Methods: A cohort study was conducted with follow-up by questionnaire of 2567 persons who had consulted the Zurich University Travel Clinic for travel health advice prior to visiting a developing country or eastern Europe. Of those questioned, 2109 (82.2%) could be evaluated.
Results: More than one-third (800; 37.9%) had a health impairment, mainly illness leading to medical consultations in 224 (10.6%) individuals. Incapacitation was reported by 303 (14.4%) travelers, accounting for 2% of the total time abroad. The most frequent reasons for incapacitation were diarrhea and the common cold, particularly when accompanied by fever. Some 57 (7.1%) travelers consulted a doctor while abroad, and more than twice as many did so after returning home.
Conclusions: This survey illustrates that despite efforts of travel medicine, the attack rate of health impairments remains virtually unchanged compared to 20 years ago. It provides one of the first overviews of incapacitation in travelers. To reduce the duration of incapacitation, one may wish to consider a travel kit which allows the patient self therapy for frequent and uncomplicated ailments.     

Impact of Melatonin on Driving Performance

Background: Because millions of people are self-prescribing melatonin for various indications, the safety aspects of this substance have become very important. The aim of our study was to determine whether or not melatonin impairs driving-related performance.
Methods: Twenty healthy men and women aged 21–57 years volunteered for this randomized, placebo-controlled, double-blind, crossover study. The crossover arms were separated by an interval of at least 4 weeks. On each testing day, melatonin 5 mg or placebo was taken at 1630 h; 60 minutes later a test series was performed, consisting of a medical examination, body sway measurement, and a standardized driving computer test battery to assess attention, reaction time, power of concentration, and sensomotor coordination. Subjective sleepiness was measured on three occasions during the test session using the Stanford Sleepiness Scale questionnaire.
Results: Just one of the 16 main variables of the driving computer test battery, the selective attention tested by signal-detection, was significantly affected by melatonin (p < .05). However, even those values were still within the normal range. Subjective sleepiness was increased by melatonin, although the result was significant only after the prolonged concentration task ( p < .05). Neither the clinical examination nor the body sway test showed signs of any drug influence.
Conclusions: The overall result of the computer test battery showed no objective adverse impact of melatonin on driving performance. However, due to the increased subjective sleepiness after administration of this hormone, caution should be exercised when driving under the influence of melatonin.     

Prevention of Travelers' Diarrhea: Ciprofloxacin versus Trimethoprim/Sulfamethoxazole in Adult Volunteers Working in Latin America and the Caribbean

Background : The objective of the study was to compare the safety and efficacy of three treatment protocols for the prevention of travelers' diarrhea: once-daily ciprofloxacin versus trimethoprim/sulfamethoxazole (TMP/SMZ) once daily versus placebo for the prevention of travelers' diarrhea.
Method : The study population was comprised of participants in 2-week medical-missions projects based in Latin America and the Caribbean. The diverse age group and varied study sites closely resembles the population of travelers who seek pretravel advice from physicians. A prospective, randomized, double-blind, placebo-controlled comparison was designed. Subjects who developed diarrhea, defined as three stools in 8 hours plus one or more signs of an enteric infection, were considered prophylaxis failures. Stool specimens were collected and examined for the presence of enteric pathogens. DNA probes were used to determine the presence of diarrheagenic E. coli. Bacterial colony blots were used. Adverse events were recorded by participants in a diary.
Results : Three hundred and forty-four subjects were entered in the study, of which two hundred and seventy-eight subjects met the criteria for the efficacy and safety review. Subjects were randomly assigned to receive ciprofloxacin (500 mg), TMP/SMZ (160/ 800 mg), or placebo. Five of the 99 (5%) subjects taking ciprofloxacin, 14 of the 87 (16%) taking TMP/SMZ, and 30 of the 92 (33%) taking placebo experienced diarrhea. Bacterial pathogens were identified more commonly in the TMP/SMZ and placebo groups than in the ciprofloxacin-treated group. The incidence of adverse reactions was 9.0%, 14.8%, and 7.5% for ciprofloxacin, TMP SMZ, and placebo subjects, respectively (p = .287).
Conclusion : Ciprofloxacin 500 mg once daily provides safe and effective prophylaxis for travelers' diarrhea and is superior to TMP/SMZ (160/800 mg). ( J Travel Med 1:136–142, 1994)     

Observational Study of Travelers' Diarrhea

Background : European air travelers returning from Algeria, Egypt, Mexico, Morocco, and Tunisia were interviewed about their experience of travelers' diseases upon arrival in Brussels. Diarrhea was mentioned by 37% of the adults and 27% of the children. These subjects were questioned about the types of measures taken, type and duration of drug treatment (if any), and about duration of diarrhea and side effects experienced.
Methods : Final analysis was performed based on 2160 interviews. The largest proportion of diarrhea was reported in the age group 15–24 years (46%).
Results : The majority of the 2160 subjects had opted for drug treatment (81%): 927 subjects for loperamide alone, 235 for loperamide in combination with nifuroxazide, and 178 for nifuroxazide alone. Other drugs had been used less frequently. The median time to recovery was 2.4 days with loperamide compared to 3.2 days with nifuroxazide and to 3.4 days for the no-treatment group.
Conclusions : A stratification of the results by severity of the diarrhea suggests a rank of antidiarrheal potency as follows: loperamide > nifuroxazide > no-drug treatment. The side effect with the highest incidence was constipation (2.4% with loperamide).     

Risk factors for orofacial and limbtruncal tardive dyskinesia in older patients: a prospective longitudinal study

Although there is a consensus that orofacial and limbtruncal subtypes of tardive dyskinesia (TD) exist and may represent distinct pathophysiologic entities, few studies have examined the incidence of and risk factors associated with the development of these TD subtypes. Two hundred and sixty-six middle-aged and elderly outpatients with a median duration of 21 days of total lifetime neuroleptic exposure at study entry were evaluated at 1- to 3-month intervals. Using mild dyskinesia in any part of the body for diagnosis of TD, the cumulative incidence of orofacial TD was 38.5 and 65.7% after 1 and 2 years, respectively, whereas that of limbtruncal TD was 18.6 and 32.6% after 1 and 2 years. Preclinical dyskinesia was predictive of both orofacial and limbtruncal TD. History of alcohol abuse or dependence was a significant predictor of orofacial TD only whereas tremor was a significant predictor of limbtruncal TD only. Findings support suggestions that orofacial and limbtruncal TD may represent specific subsyndromes with different risk factors.     

Current perceptions of travelers' diarrhea treatments and vaccines: results from a postal questionnaire survey and physician interviews

BACKGROUND: Travelers' diarrhea (TD) occurs at high frequency in individuals from industrialized countries visiting destinations in nonindustrialized countries and may result in chronic complications such as Guillain-Barré syndrome. METHODS: We distributed a questionnaire requesting information on physicians' perceptions of currently available TD products, hypothesized TD vaccines, and aspects of travelers' behavior. Some physicians also were interviewed by telephone. RESULTS: We obtained completed questionnaires from named individuals at 68 UK/US clinics. These individuals reported seeing a total of approximately 76,500 travelers per year, and estimated that 61% (UK) and 77% (US) of travelers present 2 weeks or more predeparture. More US (92%) than UK (43%) travelers are advised to purchase TD products. In both countries, 85% of travelers would be prescribed an ideal TD vaccine, but only approximately 47% (UK) and approximately 65% (US) would purchase this vaccine. About 80% of physicians would recommend an hypothesized 100% effective Campylobacter vaccine for travelers visiting regions where 30% of TD cases are caused by Campylobacter. CONCLUSIONS: Physicians support the concept of TD vaccines, including campylobacteriosis vaccines. An ideal TD vaccine might be purchased by up to 16% (UK) and 28% (US) of relevant travelers. A 100% effective Campylobacter vaccine might be purchased by over 2 million UK/US travelers per year.     

Review article: 'true' re-infection of Helicobacter pylori after successful eradication--worldwide annual rates, risk factors and clinical implications

Background  The incidence of 'true' re-infection with Helicobacter pylori after successful eradication remains uncertain.
Aim  To determine the worldwide rates, risk factors and clinical implications of 'true' re-infection of Helicobacter pylori . 'True' re-infection of H. pylori is defined as the situation where tests for H. pylori infection, which were negative for 12 months after eradication, become positive again at a later stage.
Results  Thirty six studies were identified through a literature search to be able to produce annual rates of 'true' re-infection, and data from 33 original articles were considered reliable and adequate in the further review. Generally, the reported rates varied from 0% to 23.4% in adults and from 1.9% to 9.6% in children. Most studies from developed countries reported rates of less than 1%, whereas relatively higher rates were reported in most of the developing countries. Small sample sizes included in the studies appeared to be associated with increased re-infection rates. Interfamilial transmission is the major cause of re-infection, although iatrogenic re-infection through contaminated endoscopic equipment has been reported.
Conclusion  Helicobacter pylori re-infection is not a concern in a clinical setting, especially in the developed world; however, caution must be exercised in most developing countries.     

Cholera-Brucella Cross-Reaction: A New Potential Diagnostic Problem for Travelers to Latin America

Background: Brucellosis is an endemic disease in Latin America and other countries. Serologic cross-reaction between cholera and Brucella infection is well recognized. Since the introduction to cholera in 1991 in Latin America, interpreting serologic tests has become potentially problematic. This study attempts to evaluate this problem.
Methods: Tube agglutination tests were performed to detect Brucella antibodies in 44 Peruvian adult patients with moderate to severe diarrhea due to Vibrio cholerae O1 El Tor infection. These patients had no prior history and no clinical evidence of brucellosis.
Results: False positive reactions were observed in 43.2% and 15.9% of the patients when cut-off points of ≥ 1/80 and ≥ 1/160 titer, respectively, were selected. These false positive reactions occurred within 4 to 14 days after the onset of diarrhea. The cross-reactivity decreased at the end of the fifth week (only 8.33% had a positive value at the fifth week).
Conclusions: Physicians should be alert to the false positive reaction to Brucella in patients with diarrhea. This is relevant to the evaluation of febrile illness in patients coming from developing countries where they could have been exposed to cholera.     

Safety, Immunogenicity, and Protective Efficacy of the Whole-Cell/Recombinant B Subunit (WC/rBS) Oral Cholera Vaccine Against Travelers' Diarrhea

Background : A prospective, randomized, double-blind, placebo-controlled trial of WC/rBS oral cholera vaccine was conducted in 502 U.S. college students attending summer educational programs in Mexico.
Methods : Two doses of vaccine (or placebo) were administered 10 days apart immediately after arrival in Mexico.
Results : The vaccine was free of significant adverse side effects. Anticholera toxin seroconversion was demonstrated in 86.7% of vaccinees compared to 8.2% of controls (p < .001). Postvaccination titers varied according to disease status (travelers' diarrhea) and enteropathogen isolated when disease developed. Protective efficacy (PE) against enterotoxigenic Escherichia coli (ETEC) diarrhea was 50% (95% Cl, 14–71 %), beginning 7 days after the second dose of WC/rBS. However, 74% of ETEC cases occurred within 7 days of the second dose, when no efficacy was demonstrated.
Conclusions : Vaccines employed to prevent travelers' diarrhea will likely need to be administered before arrival in a developing country to be predictably beneficial. An unexpected finding was that infection with LT-ETEC after primary oral cholera immunization appears to augment the antitoxin response to WC/rBS vaccine.     

Interventions to prevent and control food-borne diseases associated with a reduction in traveler's diarrhea in tourists to Jamaica

BACKGROUND: In 1996 a study found that approximately one in four tourists to Jamaica were affected with traveler's diarrhea (TD) during their stay. That year the Ministry of Health initiated a program for the prevention and control of TD. The aim of this ongoing program was to reduce attack rates of TD from 25% to 12% over a 5-year period by improving the environmental health and food safety standards of hotels. METHODS: Hotel-based surveillance procedures for TD were implemented in sentinel hotels in Negril and Montego Bay in 1996, Ocho Rios in 1997, and Kingston in 1999. A structured program provided training and technical assistance to nurses, food and beverage staff, and environmental sanitation personnel in the implementation of Hazard Analysis Critical Control Point principles for monitoring food safety standards. The impact of interventions on TD was assessed in a survey of tourists departing from the international airport in Montego Bay in 1997-1998 and from the international airport in Kingston in 1999-2000. The impact of the training and technical assistance program on food safety standards and practices was assessed in hotels in Ocho Rios as of 1998 and in Kingston from 1999. RESULTS: At the end of May 2002, TD incidence rates were 72% lower than in 1996, when the Ministry of Health initiated its program for the prevention and control of TD. Both hotel surveillance data and airport surveillance data suggest that the vast majority of travelers to Kingston and southern regions are not afflicted with TD during their stay. The training and technical assistance program improved compliance to food safety standards over time. CONCLUSION: Interventions to prevent and control TD in visitors to Jamaica are positively associated with a reduction in TD in the visitor population and improvements in food safety standards and practices in hotels.     

Subjective effects of additional doses of buprenorphine in patients on buprenorphine maintenance

OBJECTIVES: Buprenorphine has considerable abuse potential. Patients who are maintained on buprenorphine (for opioid dependence) further use additional doses besides its maintenance dose. Subjective effects of the additional doses of buprenorphine in patients on buprenorphine maintenance patients is focused in this study. METHODS: Nineteen subjects who were maintained on buprenorphine 4mg, s/l per day for at least 1month were admitted and given three additional doses of buprenorphine 2mg, s/l at the interval of 2h each and subjective effects were assessed with the help of standard tools after 2h of each dose and the next day also. Drug was given in a cumulative dose design in the inpatient unit of a de-addiction centre. RESULTS: Dysphoria and sleepiness increased while euphoria and drug liking decreased with additional doses of buprenorphine. These changes were statistically significant and were highest at maximum cumulative dose of 10mg. CONCLUSION: Results suggest that abuse liability of buprenorphine in these subjects is low in higher doses. However, these findings need to be replicated in this group of patients to make a comment on clinical implication.     

A survey on diarrhea and convenience of intake associated with a single-dose extended release formulation of azithromycin

The development of a single-dose extended release formulation of azithromycin (AZ-SR) improves the adherence. However, gastrointestinal side effects such as diarrhea are frequent adverse drug reactions. The aim of the present study was to investigate the incidence of patient-reported in a diarrhea and the convenience of intake of AZ-SR in an Asian population. To assess the incidence of diarrhea and convenience of intake, patient-reported in a questionnaire about the incidence, onset, duration and severity of diarrhea, shape of stool, and patients' impression on taste. The drug was prepared and used in common with the hospital pharmacy and the community pharmacy. AZ-SR was prescribed in 96 outpatients, among whom 81 patients received the medicine and the questionnaire at the hospital pharmacy or one of five neighboring community pharmacies. The recovery of the questionnaire was 40.7%. Diarrhea occurred in 18 of 33 patients (54.5%), which was more frequent than in earlier reports, although the symptom was mild (grade 1-2) and occurred in most cases within 2 days. Approximately one third of patients reported inconvenience in taking the formulation in respect of the ease (36.4%), amount (42.4%), and unpleasant bitter taste (36.4%). We report here the importance of collaboration between hospital pharmacists and community pharmacists in providing accurate drug information, including the incidence of diarrhea, to patients receiving AZ-SR.     

Etiology of travelers' diarrhea on a Caribbean island

BACKGROUND: Between December 6, 1994 and March 10, 1996, a study of the etiology of diarrhea was carried out among 332 travelers to five all-inclusive hotels in Negril, Jamaica. METHODS: Stool specimens were collected and sent to Montego Bay for laboratory analysis. Escherichia coli strains isolated at the Jamaican laboratory were sent to Houston for toxin testing. RESULTS: A recognized enteropathogen was found in 118 of the 332 (35.5%) cases. Enterotoxigenic E. coli (ETEC) were the most commonly identified pathogen (87/332; 26.2%) followed by Salmonella (4.2%) and Shigella (4.2%). Clustering of etiologically defined cases was studied at each hotel. A cluster was defined as 2 or more cases with the same pathogen identified in the same hotel within 7 days. In the 3 hotels with the highest number of cases of diarrhea, enteropathogens were part of a cluster in 65 of 99 cases (65.7%) of diarrhea of which an etiologic agent was identified. In the other 2 hotels, only 4 of 20 cases (20%) occurred in clusters. CONCLUSIONS: A total of 25 clusters of travelers' diarrhea cases was detected at the five hotels during the study period. Seventeen of 25 (68%) ETEC isolations occurred as part of a clustering of diarrhea cases. The largest outbreak of pathogen-identified diarrhea consisted of 7 cases of ETEC producing both heat-stable and heat-labile enterotoxins. In the Jamaican hotels with all inclusive meal packages most diarrhea cases occurred as small clusters, presumably as the result of foodborne outbreaks.     

Enterotoxigenic Escherichia coli heat-labile toxin seroconversion in US travelers to Mexico

Background and Aims.  Enterotoxigenic Escherichia coli (ETEC) is the most common bacterial pathogen isolated from travelers suffering of diarrhea. Exposure to heat-labile toxin (LT) produces a high rate of seroconversion. However, the role of LT-producing ETEC (LT-ETEC) as a cause of diarrhea is controversial. We conducted a cohort study in US students traveling to Mexico to assess the ETEC-LT seroconversion rate after natural exposure.
Methods.  Participants provided a serum sample on arrival and departure and a stool sample when ill. ETEC-LT immunoglobulin G antibodies were measured by enzyme-linked immunosorbent assay, and LT-ETEC were detected by means of polymerase chain reaction done on fecal DNA.
Results.  A total of 422 participants with a mean age of 34.5 years were followed a mean of 19.9 days; 304 were females (72.0%), and 319 (75.6%) traveled during the summer months. In total, 177 individuals (41.9%) developed travelers' diarrhea and 33.9% had LT-ETEC identified in their stools. Among individuals having an LT-ETEC strain, 74% seroconverted compared to 11% of those not having diarrhea ( p < 0.0001). When analyzed with a logistic regression model, the odds of seroconversion were significantly reduced in participants not having LT-ETEC in their stool (odds ratio = 0.1, p < 0.0001) after adjusting for season, length of stay, age, gender, race, and ethnicity.
Conclusion.  In US young adults traveling to Mexico, ETEC-LT seroconversion reliably identifies individuals naturally exposed to ETEC and correlates with symptomatic illness, length and season of travel.