Enterotoxigenic Escherichia coli (ETEC) are diverse pathogens that express heat-labile (LT) and/or heat-stable (ST) enterotoxins, yet little is known about whether epidemiologic patterns of pediatric ETEC diarrhea vary by the expressed ETEC toxin phenotype. In total, 242 Egyptian children aged !3 years were prospectively followed in 1993-1995. ETEC episodes were detected during twice-weekly home visits, and asymptomatic ETEC excretion was identified from monthly cross-sectional surveys. ETEC episodes were 0.6 per child-year. ST-only ETEC was 2.6 times ( ) more common in warmer than cooler months, while LT-only P ! .001 ETEC showed no seasonal variation. Ownership of a household sanitary latrine, but not breast-feeding, was associated with a lower risk of both enterotoxin phenotypes. Coexpression of a colonization factor by LT-or ST-only ETEC strengthened the association with diarrhea. These findings indicate that the epidemiologic patterns of LT-only and ST-only ETEC are not identical and that disease interventions should include improved household sanitation.It has been estimated that enterotoxigenic Escherichia coli (ETEC) causes nearly 400 million diarrheal episodes and 700,000 deaths annually among children !5 years old [1]. Even

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The voltage across the cell membrane of human T-lymphocyte cell lines was recorded by the whole cell patch clamp technique. We studied how this voltage fluctuated in time and found that these fluctuations have fractal characteristics. We used the Hurst rescaled range analysis and the power spectrum of the increments of the voltage (sampled at 0.01-sec intervals) to characterize the time correlations in these voltage fluctuations. Although there was great variability in the shape of these fluctuations from different cells, they all could be represented by the same fractal form. This form displayed two different regimes. At short lags, the Hurst exponent H = 0.76 +/- 0.05 (SD) and, at long lags, H = 0.26 +/- 0.04 (SD). This finding indicated that, over short time intervals, the correlations were persistent (H > 0.5), that is, increases in the membrane voltage were more likely to be followed by additional increases. However, over long time intervals, the correlations were antipersistent (H < 0.5), that is, increases in the membrane voltage were more likely to be followed by voltage decreases. Within each time regime, the increments in the fluctuations had characteristics that were consistent with those of fractional Gaussian noise (fGn), and the membrane voltage as a function of time had characteristics that were consistent with those of fractional Brownian motion (fBm).

Transportation of clinical samples and long-term recoverability of pathogens are critical to epidemiological studies, particularly when conditions do not permit immediate processing. This study confirms that Cary-Blair medium (CB) is suitable for the preservation of Salmonella and Shigella isolates for more than 2 weeks at 25, 4, or ؊70 C. Campylobacter jejuni was not recovered after 2 days of storage in CB at 25 C when an inoculum of 12 ؋ 10 8 cells per ml was used. Lower temperatures supported the recovery of this organism for 6 days. When individual pathogens were preserved with stools in CB and incubated at 25, 4, or ؊70 C, the Salmonella and Shigella concentrations dropped from 12 ؋ 10 8 cells to 1 ؋ 10 3 or 1 ؋ 10 4 cells per ml within 2 days and then remained stable for the rest of the observation period (15 days). C. jejuni survived preservation with stools for 5 to 9 days. The addition of blood and glycerol to CB improved the recoverability of all enteropathogens, particularly C. jejuni, which was consistently detected for 7 to 9 days at the different preservation temperatures used. When trypticase soy broth-glycerol (freezing medium), with or without blood, was used, there was little or no decrease in the Salmonella and Shigella concentrations during 2 weeks of preservation with stools at ؊70 C. C. jejuni demonstrated a relatively sustained high concentration in Trypticase soy broth-glycerol with 5% blood. The use of defibrinated, laked sheep blood as a long-term freezing medium supported the recovery of low concentrations of Salmonella and Shigella spp. (10 2 to 10 3 cells per ml) for more than 14 weeks. Recovery of C. jejuni was consistent for 7 weeks when an initial concentration of 10 6 cells per ml was present in stools. Laked blood provided a simple, sterile, and inexpensive medium for the preservation of individual isolates and clinical samples.

This study investigated the microbial causes of diarrheal disease among U.S. troops deployed near Alexandria, Egypt, during October 1995. Bacterial causes associated with 19 cases of diarrhea included: enterotoxigenic Escherichia coli (ETEC), 42% (21% heat-stable, 11% heat-labile, and 11% heat-stable/ heat-labile producers); enteropathogenic E. coli (5.3%); and enteroadherent E. coli (42%). Four cases of diarrhea were associated with enteroaggregative E. coli based on probe analysis for enteroaggregative heat-stable enterotoxin 1. Protozoan causes included; Entamoeba histolytica (11%), E. hartmanni (5%), E. nana (5%), Blastocystis hominis (5%), Chilomastix mesnili (11%), Dientamoeba fragilis (5%), Entamoeba coli (5%), and Cryptosporidium (5%). Shigella, Aeromonas, Plesiomonas, Vibrio, Campylobacter, and Salmonella were not detected. Of the eight ETEC cases, one was colonization factor antigen (CFA)/I only, one was both CFA/I and CFA/III, three were CFA/II, two were CFA/IV, and two were CFA-negative. Antibiograms of the ETEC and enteroadherent E. coli strains showed that all isolates were susceptible to norfloxacin, ciprofloxacin, and nalidixic acid but resistant to ampicillin, tetracycline, chloramphenicol, and sulfamethoxazole.