RESUMEN
BACKGROUND: Postinfectious irritable bowel syndrome (PI-IBS) has been reported as a complication of bacterial diarrhea including travelers' diarrhea (TD). This study assessed the role of TD among US students in Mexico in triggering the onset of persistent abdominal symptoms (PAS) and IBS. METHODS: We conducted a 6-month follow-up of a cohort of 817 US students in Mexico as short-term study to assess the frequency of PAS and IBS. Using Rome II criteria for IBS, groups of students with PAS were then categorized as PI-IBS if they met the symptom criteria for IBS or as suffering from functional abdominal disorder (FAD) if they did not meet the criteria. RESULTS: FAD and IBS were commonly found in US students 6 months after leaving Mexico. Important variables in their development were younger adult age, longer stays in Mexico and occurrence of acute diarrhea while in Mexico. Diarrhea while in Mexico occurred more commonly for those later diagnosed with FAD, 101/196 (52%), relative risk (RR) = 1.5 [confidence interval (CI) 1.2-1.8; p = 0.001]; IBS, 20/32 (63%), RR = 2.5 (CI 1.2-5.0; p = 0.007); and PAS (FAD + IBS), 121/228 (53%), RR = 1.5 (CI 1.2-1.8; p < 0.001) compared with subjects who had experienced diarrhea while in Mexico but were not diagnosed with PAS at 6 months, 227/589 (39%). Diarrhea caused by heat-labile enterotoxin-producing enterotoxigenic Escherichia coli or Providencia ssp. demonstrated a greater risk of developing PAS. CONCLUSIONS: PAS occurred commonly in a subset of younger adult travelers who stayed longer in Mexico and experienced acute diarrhea while there. Further studies with this cohort will focus on host genetic associations with the development of PAS.
Asunto(s)
Diarrea , Escherichia coli/aislamiento & purificación , Síndrome del Colon Irritable , Providencia/aislamiento & purificación , Viaje/estadística & datos numéricos , Adolescente , Adulto , Edad de Inicio , Diarrea/complicaciones , Diarrea/epidemiología , Diarrea/microbiología , Diarrea/fisiopatología , Femenino , Humanos , Síndrome del Colon Irritable/diagnóstico , Síndrome del Colon Irritable/epidemiología , Síndrome del Colon Irritable/etiología , Síndrome del Colon Irritable/fisiopatología , Masculino , México/epidemiología , Medición de Riesgo , Evaluación de Síntomas , Factores de Tiempo , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND: Under normal conditions, the expression of CD14, which is the principal receptor for bacterial lipopolysaccharide, is down-regulated in the intestinal mucosa but increases in response to inflammatory stimuli. The aim of the present study was to investigate whether fecal CD14 levels increased in response to infection with diarrheagenic Escherichia coli and whether single nucleotide polymorphisms (SNPs) in the CD14 gene were associated with an increased susceptibility to traveler's diarrhea (TD) in US visitors to Mexico. METHODS: Six SNPs located at the promoter, exon, and untranslated regions of CD14 were typed in a prospective cohort study of 1360 visitors to Mexico at risk for TD. Stools from visitors with TD were studied for enteric pathogens by culture, colony hybridization, and polymerase chain reaction. Fecal soluble CD14 (sCD14) was measured in a subgroup of 203 adults with diarrhea and 66 healthy controls by enzyme-linked immunosorbent assay. RESULTS: The minor allele frequencies for CD14 SNPs were significantly different among the various racial and ethnic groups studied. Two SNPs in the promoter region of CD14 (-159 C > T; rs2569190 and -4191 C > T; rs5744441) were found to be associated with TD in White visitors. The -159 TT genotype was associated with a higher risk for TD (Relative risk [RR], 1.21; 95% confidence interval [CI], 1.05-1.38; P = .008), whereas individuals with the -4191 TT genotype were protected from infection (RR, 0.82; 95% CI, 0.71-0.92; P = .006). Subjects with TD excreted higher levels of fecal CD14 than did healthy controls (33,480 pg/mL vs 6178 pg/mL; P < .02). Fecal sCD14 levels were higher in stool samples from visitors with TD and the -159 TT genotype than they were in visitors with the CC/CT genotypes (P = .02), and stool samples from subjects with the -4191 CC genotype had higher fecal sCD14 levels than did stool samples from visitors with the CT/TT (P = .005) genotype. In a multivariate analysis with haplotypes constructed with the 6 SNPs studied, subjects with the haplotype containing the -159 C and the -4191 T allele were less likely to acquire TD (P = .015). CONCLUSIONS: Our study suggests that CD14 levels increase in response to bacterial diarrhea and that polymorphisms in the CD14 gene influence susceptibility to TD. Intestinal CD14 plays an important role in the innate immune response to enteric pathogens.
Asunto(s)
Diarrea/genética , Infecciones por Escherichia coli/genética , Receptores de Lipopolisacáridos/genética , Polimorfismo de Nucleótido Simple , Regiones Promotoras Genéticas , Viaje , Adolescente , Adulto , Canadá , Estudios de Cohortes , Diarrea/epidemiología , Diarrea/inmunología , Susceptibilidad a Enfermedades , Ensayo de Inmunoadsorción Enzimática , Infecciones por Escherichia coli/epidemiología , Infecciones por Escherichia coli/inmunología , Heces/química , Heces/microbiología , Femenino , Humanos , Receptores de Lipopolisacáridos/análisis , Masculino , México , Hibridación de Ácido Nucleico , Reacción en Cadena de la Polimerasa , Estudios Prospectivos , Estados Unidos , Adulto JovenRESUMEN
BACKGROUND: Up to 60% of the US visitors to Mexico develop travelers' diarrhea (TD). In Mexico, rates of diarrhea have been associated with the rainy season and increase in ambient temperature. However, the seasonality of the various diarrheagenic Escherichia coli pathotypes in travelers has not been well described. OBJECTIVE: A study was undertaken to determine if ambient temperature and rainfall have an impact on the acquisition of TD due to different diarrheagenic E coli pathotypes in Mexico. METHODS: We conducted a cohort study of the US adult students traveling to Cuernavaca, Mexico, who were followed during their stay and provided a stool sample with the onset of TD. The presence of E coli was analyzed by a direct fecal multiplex polymerase chain reaction for common E coli pathotypes including enterotoxigenic, enteropathogenic, enteroinvasive, shiga toxin-producing, and enteroaggregative E coli (ETEC, EPEC, EIEC, STEC, and EAEC respectively). The presence of pathotypes was correlated with daily rainfall, average, maximum, and minimum temperatures. RESULTS: A total of 515 adults were enrolled from January 2006 to February 2007. The weekly attack rate of TD for newly arrived travelers was lower in the winter months (range 6.8%-16.3%) than in summer months (range 11.5%-25%; p = 0.05). The rate of ETEC infection increased by 7% for each degree centigrade increase in weekly ambient temperature (p = 0.003). In contrast, EPEC and EAEC were identified in similar proportions during the winter and summer seasons. CONCLUSIONS: Temperature variations in central Mexico influenced the rate of ETEC but not EAEC-associated diarrhea in the US visitors. This epidemiological finding could influence seasonal recommendations for the use of ETEC vaccines in Mexico.
Asunto(s)
Infecciones por Escherichia coli/epidemiología , Infecciones por Escherichia coli/microbiología , Escherichia coli/aislamiento & purificación , Heces/microbiología , Estudiantes/estadística & datos numéricos , Viaje , Adulto , Diarrea/epidemiología , Diarrea/microbiología , Escherichia coli Enteropatógena/aislamiento & purificación , Escherichia coli Enterotoxigénica/aislamiento & purificación , Escherichia coli/clasificación , Femenino , Humanos , Masculino , México , Persona de Mediana Edad , Estudios Prospectivos , Factores de Riesgo , Estaciones del Año , Escherichia coli Shiga-Toxigénica/aislamiento & purificación , Estados Unidos/epidemiología , Adulto JovenRESUMEN
Campylobacter jejuni is an unusual cause of travelers' diarrhea acquired in Mexico, but previous studies have relied only on stool culture for diagnosis. We conducted a cohort study to determine if antibody seroconversion to C jejuni would better reflect the occurrence of infection acquired in Mexico. Serum IgG, IgA, and IgM antibodies to Campylobacter seroconverted in only 2 of 353 participants (0.6%). These data further support that C jejuni infection is an unusual cause of travelers' diarrhea in US visitors to Mexico.
Asunto(s)
Anticuerpos Antibacterianos/análisis , Infecciones por Campylobacter/inmunología , Campylobacter jejuni/fisiología , Diarrea/microbiología , Inmunoglobulinas/análisis , Viaje , Adolescente , Adulto , Infecciones por Campylobacter/diagnóstico , Infecciones por Campylobacter/epidemiología , Campylobacter jejuni/aislamiento & purificación , Niño , Estudios de Cohortes , Diarrea/diagnóstico , Diarrea/epidemiología , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Inmunoglobulina A/análisis , Inmunoglobulina G/análisis , Inmunoglobulina M/análisis , Masculino , México , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Factores de Riesgo , Estados Unidos , Adulto JovenRESUMEN
We studied 1,179 North American travelers who visited Mexico from 2005 to 2007. Travelers' diarrhea (TD) was reported by 521 (44%) participants. Among subjects with TD, 218 cases were examined for cryptosporidiosis by polymerase chain reaction (PCR) and enzyme-linked immunoassays (ELISA). There were 14 (6%) cases of cryptosporidiosis and 141 cases (64%) of bacterial diarrhea. Compared with bacterial diarrhea, a longer stay in Mexico was a risk factor for cryptosporidiosis. Additionally, Cryptosporidium cases passed greater number of watery stools (P < 0.05), suffered more episodes of diarrhea (P < or = 0.05), and were more likely to experience tenesmus (P < or = 0.05) compared with bacterial causes of TD. ELISA detected seven (3%) cases of Cryptosporidium, whereas PCR identified an additional seven cases (6%). Speciation by 18SrRNA sequencing showed that 13 cases were caused by C. parvum and only 1 case was caused by C. hominis. ELISA showed a sensitivity of 50% and specificity of 100% compared with PCR.
Asunto(s)
Criptosporidiosis/epidemiología , Diarrea/epidemiología , Diarrea/parasitología , Viaje , Adolescente , Adulto , Animales , Canadá/epidemiología , Cryptosporidium/clasificación , Ensayo de Inmunoadsorción Enzimática , Humanos , México/epidemiología , Oportunidad Relativa , Reacción en Cadena de la Polimerasa , Factores de Riesgo , Sensibilidad y Especificidad , Factores de Tiempo , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND: Diarrhea affects 40%-60% of travelers from industrialized nations who visit developing countries and is due to bacterial, viral, and parasitic agents. Lactoferrin is bactericidal to enteric pathogens, modulates the intestinal immune response, and is excreted in stool in response to infection with intestinal organisms. We investigated the impact that selected single-nucleotide polymorphisms (SNPs) in the human lactoferrin gene have on susceptibility to traveler's diarrhea. METHODS: Adults who had recently arrived in Mexico were studied prospectively for the occurrence and causal agent(s) of traveler's diarrhea, and genotyping was performed for 9 distinct lactoferrin SNPs. RESULTS: Of the 9 SNPs studied, only 1 SNP (located in exon 15) was associated with traveler's diarrhea (P=.004). When compared with healthy travelers, and after adjustment for known risk factors for traveler's diarrhea (such as age and duration and season of travel), subjects with the T/T genotype in amino acid position 632 were more likely to develop traveler's diarrhea (67% vs. 33%; relative risk [RR], 1.4; 95% CI, 1.2-1.7; P<.001), to have diarrhea with a pathogen identified (RR, 1.3; 95% CI, 1.1-1.6; P=.03), and to have a marker of intestinal inflammation in stool specimens (blood, mucus, or white blood cells; 52% vs. 38%; P=.036). The association was also significant when norovirus was not identified in stool samples (RR, 1.34; 95% CI, 1.06-1.34; P=.01). CONCLUSIONS: The T/T genotype in position codon 632 of the lactoferrin gene is associated with susceptibility to diarrhea in North Americans traveling to Mexico.