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The ecology of Escherichia coli O157:H7 is not well understood. The aims of this study were to determine the prevalence of and characterize E. coli O157:H7 associated with houseflies (HF). Musca domestica L. HF (n ‫؍‬ 3,440) were collected from two sites on a cattle farm over a 4-month period and processed individually for E. coli O157:H7 isolation and quantification. The prevalence of E. coli O157:H7 was 2.9 and 1.4% in HF collected from feed bunks and a cattle feed storage shed, respectively. E. coli O157:H7 counts ranged from 3.0 ؋ 10 1 to 1.5 ؋ 10 5 CFU among the positive HF. PCR analysis of the E. coli O157:H7 isolates revealed that 90.4, 99.2, 99.2, and 100% of them (n ‫؍‬ 125) possessed the stx1, stx2, eaeA, and fliC genes, respectively. Large populations of HF on cattle farms may play a role in the dissemination of E. coli O157:H7 among animals and to the surrounding environment.Enterohemorrhagic Escherichia coli O157:H7 is a wellknown causative agent of hemorrhagic colitis and hemolytic uremic syndrome in humans. Outbreaks of the food-borne illness caused by E. coli O157:H7 have been reported throughout the northern hemisphere, most frequently in the United States, Canada, Japan, and the United Kingdom. In the United States alone, E. coli O157:H7 causes more than 73,000 cases of human infection every year (11). E. coli O157:H7 strains commonly carry verotoxins (encoded by the stx1 and stx2 genes) and factors for the attachment to the host mucosa, including intimin (encoded by the eaeA gene) (11). The low infectious dose and high virulence of E. coli O157:H7 make infections severe and life-threatening, particularly for young children, the elderly, and those with weakened immune systems (11). The main reservoir for E. coli O157:H7 is the intestinal tracts of healthy cattle. Individual cattle are transiently colonized and shed E. coli O157:H7 in their feces (1). The sources of E. coli O157:H7, which colonizes cattle, are not well understood, and little is known about the ecology of E. coli O157:H7 in the environment (1). Additionally, the high variability in the prevalence of E. coli O157:H7 among cattle suggests the possibility of a reservoir of E. coli O157:H7 external to cattle. However, other than the detection of E. coli O157:H7 in nonbovine animals, including sheep, horses, dogs, and wild birds (1), the ecology of this pathogen has not been extensively studied.One of the potential modes of dissemination of this pathogen in the environment is by insects that are associated with animal feces and manure, primarily houseflies (HF; Musca domestica L.). HF larvae develop in animal feces, including cattle manure. Consequently, HF commonly build up very large populations on cattle farms and in other animal facilities. Previously, a laboratory-based study demonstrated that E. coli O157:H7 ingested by HF remained viable in the fly excreta and that the HF were able to carry and disseminate E. coli for several days (9). In Japan, HF were implicated in the transmission of E. coli O157:H7 from reservoir animals to...

Seawater and organic material (live and/or dead matter deposited on any substratum submersed in seawater) were collected during the cool weather season from a coast of the Seto-Inland Sea, Japan, and analyzed to determine Vibrio parahaemolyticus densities and the occurrence of pathogenic strains, defined as those possessing tdh and/or trh genes by the polymerase chain reaction (PCR), using isolated DNA from enrichment culture of the samples. About 95% of the samples were positive for V. parahaemolyticus (with densities of 3 to >1400 cells per 100 ml water or 10 g organic samples) by the most-probable-number (MPN)-PCR technique with species-specific toxR primers, but only 40% were positive by the conventional MPN-culture technique (with densities ranging from 3 to 240 cells per 100 ml water or 10 g organics). Furthermore, the tdh and trh genes were positive in 55% and 20% of samples, respectively, by the MPN-PCR technique. No tdh and trh gene-positive strains were isolated by the conventional MPN-culture procedure. The difference in detection between the MPN-culture and the MPN-PCR techniques appeared to be significant and may be attributed to different detection sensitivities and other factors.

A test of the suitability of subsurface drip irrigation (SDI) for alfalfa (Medicago sativa L) compared to a sprinkler, was conducted on a Kansas producer's field where the soil is loam. The treatments included drip tape spacing of 60, 40, and 30 inches placed at depths of 18 and 12 inches. A nearby plot irrigated by a center pivot sprinkler was seeded to alfalfa and used for comparison. Seedling emergence and yield were adversely affected at 60 inch spacing, while the depth of placement of drip tapes (18 and 12 inches) showed no effect on yield. The site served for education and allowed comparison between SDI tape spacing and center pivot system.