A B S T R A C T The site and characteristics of gastrointestinal electrolyte loss were investigated in eight dogs with experimental cholera induced by orogastric administration of 6-hr broth cultures of Vibrio cholerae, strain Ogawa 395. In these animals, all electrolyte losses originated in the small bowel, predominantly from the jejunum and ileum.The bicarbonate concentration of the small bowel fluid showed a progressive increase from duodenum, where it was less than that of plasma, to the terminal ileum, where it was significantly greater than that of simultaneously obtained plasma.Studies of the responses of chronic ThiryVella jejunal loops (five dogs) and chronic ThiryVella ileal loops (five dogs) to intraluminal challenge by cholera exotoxin demonstrated that all loops exhibited isotonic electrolyte loss for a 14-18 hr period after challenge. The bicarbonate concentration of fluid produced by exotoxin-challenged jejunal loops was not significantly different from that of plasma, whereas the ileal loops produced fluid with a bicarbonate concentration approximately three times that of plasma.

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A community-based longitudinal study was conducted in Matlab, a rural area of Bangladesh, from May 1988 to April 1989 to examine the associations among malnutrition, cell-mediated immune deficiency, and the incidence of diarrhea in children under age 5 years. A cohort of 705 children was followed for a year; illnesses were ascertained every fourth day by home visits, anthropometric status was evaluated monthly, and cell-mediated immune status was assessed by a multiple antigen skin test at baseline and every 3 months. The diarrhea incidence rate was 4.6 episodes per year. Approximately three quarters of the children were below -2 z score weight for age and height for age, and about a third were below -2 z score weight for height. There was a modest association between undernutrition and the incidence of diarrhea. About 10-20% of the study children were anergic, and these children experienced a 50% increased incidence of diarrhea compared with their immunocompetent counterparts. This association persisted after controlling for the effects of age, nutritional status, socioeconomic status, and history of diarrhea in the previous 3 months. Malnutrition and cell-mediated immune deficiency were important independent risk factors for the occurrence of diarrhea and must both be considered in the design of interventions for the control of this condition.

Enterotoxigenic strains of Escherichia coli, a significant cause of acute, watery, cholera-like diarrhea, were isolated from 23 of 65 patients with diarrhea in whom no other enteric pathogens were found during one week (November 1974) at the Cholera Research Hospital, Dacca, Bangladesh. Diarrhea associated with enterotoxigenic strains of E. coli occurred primarily in adults but affected persons of all age groups and could not be distinguished from cholera or from other cholera-like diarrhea on clinical grounds. Routine bacteriologic methods were inadequate for identification of enterotoxigenic E. coli as the etiologic agent of the diarrhea. The enterotoxigenic E. coli, producing heat-stable and/or heat-labile enterotoxin, were detected by use of assays in the Y1 adrenal cell, the Chinese hamster ovary cell, the rabbit ileal loop, and the infant mouse. The two tissue culture assays yielded comparable results in tests with 640 (193 positive, 447 negative) of 643 isolates of E. coli. The results of this study support the idea that enterotoxigenic E. coli play a significant role as pathogens in the etiology of acute watery diarrhea.

A community-based longitudinal study conducted in rural Bangladesh investigated the association between nutritional status, cell-mediated immune status and acute upper respiratory infections (URI). A total of 696 children aged 0-59 months was followed prospectively for 1 y yielding 183,865 child-days' observation. Trained field workers visited each child every 4th d and collected morbidity data on symptoms suggesting URI (cough, fever, nasal discharge) for the preceding 3 d by recall. On the day of visit they examined each child reporting cough and/or fever to record the temperature, presence of nasal discharge, rate of respiration and presence of chest indrawing. Anthropometry for all children was conducted monthly. Cell-mediated immune competence was assessed by a multiple antigen skin test at baseline and thereafter every 3 months. The incidence of URI was 5.3 episodes per child-year observed. Approximately three-quarters of the study children were below -2 Z-score weight for age and height for age, and a quarter below -2 Z-score weight for height. During different test periods 9-21% of the study children did not respond to any of the test antigens. In a regression model children < -2 Z-score for weight for height had 16% [odds ratio (OR) 1.16, 95% confidence interval (CI) 1.03-1.31, p = 0.01] higher risk of developing URI. Anergic children had 20% higher risk (OR 1.20, CI 1.05-1.38, p = 0.009) of URI than immunocompetent children. The study demonstrated that wasting and depressed cell-mediated immunity (CMI), but not stunting, were associated with the incidence of URI among rural Bangladeshi children.

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Enterotoxigenic Escherichia coli (ETEC) is a common cause of bacterial infection leading to acute watery diarrhea in infants and young children. Although the prevalence of ETEC is high in Bangladesh and infections can be spread through food and contaminated water, limited information is available about ETEC in the surface water. We carried out studies to isolate ETEC from surface water samples from ponds, rivers, and a lake from a site close to field areas known to have a high incidence of diarrhea in Dhaka, Bangladesh, and Matlab, Bangladesh. ETEC strains isolated from the water sources were compared with ETEC strains isolated from patients with diarrhea at two hospitals in these areas. ETEC were isolated from 30% (45 of 150) of the samples from the surface water sources and 19% (518 of 2700) of the clinical specimens. One hundred ETEC strains isolated from patients with similar phenotypes as the environmental strains were compared for phenotypic and genotypic properties. The most common O serogroups on ETEC were O6, O25, O78, O115, and O126 in both types of strains. Pulsed-field gel electrophoresis analyses of the ETEC strains showed that multiple clones of ETEC were present within each colonization factor type and that some clones detected in the environment were also isolated from the stools of patients. The strains showed multiple and similar antibiotic resistance patterns. This study shows that ETEC is prevalent in surface water sources in Bangladesh suggesting a possible reason for the endemicity of this pathogen in Bangladesh.

The incidence of diarrhea, respiratory disease, and skin infections was pro