Diarrheal Disease In Humans Research Articles

Screening for coinfection with Cryptosporidium and Giardia in Oregon public health clinic patients.

During 1984, we screened 1,710 local public health clinic patients for Giardia and Cryptosporidium. Six patients (0.35 per cent) were positive for Cryptosporidium, and 214 (12.5 per cent) were positive for Giardia. One patient was positive for both parasites. In contrast to other reported studies, no evidence was found for an association between the two parasites (odds ratio = 1.39, 95 per cent CI 0.16, 11.8). The apparent prevalence of Cryptosporidium in our study population was lower than has been reported previously. More laboratory screening could contribute to a better understanding of the distribution of Cryptosporidium and its role in human diarrheal disease, especially in immunocompetent patients.

Acetate and citrate stimulate water and sodium absorption in the human jejunum.

Using a standard perfusion technique, the organic anions acetate (50 mmol/l) and citrate (5 mmol/l) have been shown to stimulate absorption of water and sodium from the human jejunum. These observations may support further the rationale for including acetate or citrate in oral rehydration solutions for the treatment of acute diarrhoeal disease in humans.

1090 ANTIGENICALLY DISTINCT ROTAVIRUSES ARE COMMON CAUSES OF DIARRHEA IN HUMANS

Rotaviruses (RV) are major causes of diarrheal disease in humans and other animals. Until recently, it was thought that all RVs shared a common antigen, and a vaccine based on this principle is undergoing field testing in humans. However, rotavirus-like agents (RVLA) which are morphologically indistinguishable from RVs but which do not share any antigenic similarity to standard RVs have recently been isolated from cows, piglets, birds, and humans. The role of these agents in human disease has not been extensively studied. We recently discovered a RVLA which is capable of infecting infant rats (J. Virol. 52:94-98, 1984). We found that fecal samples from adults and humans with acute gastroenteritis can transmit an identical disease to the infant rats. The infection is characterized by typical pathological changes in the gastrointestinal epithelial ceils and by the passage of viral particles with a characteristic pattern of double-stranded, segmented RNA. We have devised enzyme immunoassays for the detection of RVLA antigen and antibody. The application of these assays to human specimens has indicated that RVLA infection is common in young children and that infection with RVLA can be associated with severe gastroenteritis. RVLA may be an important new agent of gastroenteritis in humans and animals.

Waterborne transmission ofCampylobacter enteritis

Campylobacter jejuni is an important cause of human diarrheal disease throughout the world and likeSalmonella enteritidis, has a large animal reservoir which includes most of man's domestic animals. Until recently, it has been difficult to trace the chain of transmission from animals to man because of inadequate environmental sampling techniques and means to distinguish strains. Recent improvements in these techniques have made environmental studies more feasible in 2 water-related out-breaks.In 1 study,C. jejuni was found to be an important cause of sporadic, summertime diarrheal disease among hikers in national wilderness areas of Wyoming. In this setting, illness was significantly associated with drinking untreated surface water. SubsequentlyC. jejuni was isolated from surface water, including mountian streams, and from animals in the area. Some of the environmental isolates were serotypically identical to strains isolated from humans.A second study occurred as a result of an outbreak of Campylobacter enteritis in a community in northern Illinois which was epidemiologically associated with the community water system.Campylobacter jejuni was isolated from several surface water sources and from the implicated water system. These studies demonstrate that environmental isolation ofC. jejuni is now possible and may add to our understanding of disease transmission.

Inhibition of Escherichia coli heat-stable enterotoxin effects on intestinal guanylate cyclase and fluid secretion by quinacrine

Enterotoxigenic Escherichia coli may produce a heat-stable enterotoxin (ST) that causes diarrheal disease in humans and in animals ST activates particulate guanylate cyclase in intestinal mucosal cells and causes intestinal fluid secretion. In this study, we examined the effects of quinacrine on ST activation of guanylate cyclase and ST-mediated intestinal fluid secretion. Quinacrine significantly reduced ST activation of particulate guanylate cyclase in rat intestinal tissue. Additionally, quinacrine reduced ST-mediated fluid secretion in a rat intestinal loop assay (P < 0.05). In the suckling mouse model, subcutaneous quinacrine (0.1 μmole/mouse) reduced ST-induced fluid secretion at a submaximally effective dose of the toxin, but it did not reduce ST-mediated fluid secretion at a near maximally effective dose. Quinacrine (0.1 μmole/mouse) did not significantly reduce intestinal fluid secretion induced by the analog of cyclic GMP, 8-bromo cyclic GMP. However, at a higher concentration of quinacrine (1 μmole/mouse), significant inhibition of 8-bromo cyclic GMP-induced secretion was observed. Inhibition by the antimalarial agent quinacrine of ST-induced fluid secretion, by a block prior to guanylate cyclase activation, suggests a possible role for a phospholipase early in the sequence of events of ST activation of guanylate cyclase. The results suggest that ST may activate membrane phospholipases prior to ST activation of guanylate cyclase.

Ultrasensitive enzymatic radioimmunoassay: application to detection of cholera toxin and rotavirus.

Rotavirus and enterotoxin-producing bacteria are major causes of diarrheal disease in humans. A method of rapid diagnosis, ultrasensitive enzymatic radioimmunoassay, has been developed to quantitatively detect cholera toxin and rotavirus. The method uses features of both enzyme-linked immunosorbent assay and radioimmunoassay; however, the sensitivity of the assay is 100- to 1000-fold more sensitive than the two parent assays. Ultrasensitive enzymatic radioimmunoassay should also be useful in measuring other biologically important agents such as drugs and hormones.

Search for Heat-Labile Enterotoxigenic Escherichia coli in Humans, Livestock, Food, and Water in a Community in the Philippines

Environmental sources of heat-labile enterotoxigenic Escherichia coli are unknown. The feces of 1,086 inhabitants (approximately 5%) of a small town in the Philippines, 28 pigs, and 10 water buffalo were cultured for enteric bacterial pathogens. Twenty-seven persons harbored pathogenic bacteria: five individuals had enterotoxigenic E. coli, 11 Salmonella species, nine Vibrio parahaemolyticus, one Shigella boydii, and one nonagglutinable Vibrio. Enterotoxigenic E. coli were isolated from two of 28 pigs and from one of 10 water buffalo. Cultures of 26 pieces of beef, 25 pieces of pork, and 52 leafy vegetables obtained from a community market failed to grow enterotoxigenic E. coli. None of 47 samples of contaminated surface water contained this pathogen. Serotypes of human and animal strains of enterotoxigenic E. coli were different, although E. coli O78:H12 isolated from a pig has previously been incriminated in human diarrheal disease. In this limited survey of a Philippine community, enterotoxigenic E. coli were isolated from humans and livestock. The possibility that enterotoxigenic E. coli infections are zoonotic warrants further investigation.