Publications

disinfection of bacillus subtilis spores with chlorine dioxide: a bench-scale and pilot-scale study.	chlorine dioxide (clo2) inactivation of bacillus subtilis atcc 19659 spores was examined at pilot-scale during periods representative of winter and summer temperature extremes at the britannia water treatment plant in ottawa, canada. in addition, bench-scale experiments using the same source water (ottawa river, ontario, canada), as well as buffered and unbuffered laboratory waters were conducted using b. subtilis spores. bench-scale inactivation of b. subtilis spores by clo2 was similar to repo ...	2002	11996351
influence of temperature on cryptosporidium parvum oocyst infectivity in river water samples as detected by tissue culture assay.	cryptosporidium parvum oocysts were stored in 1-ml aliquots of filtered river water at -20, 4, 10, and 21-23 c in the dark. oocysts were also added to filter-sterilized river water samples and stored at 21-23 c. the infectivity of oocysts stored under different conditions was assayed at weekly intervals through infection of human adenocarcinoma ileocecal (hct-8) cell monolayers. wells containing between 10 and 100 foci of infection were enumerated by immunofluorescent microscopy, and the number ...	2002	12099446
prevalence of giardia and cryptosporidium in beef cows in southern ontario and in beef calves in southern british columbia.	in 1998 and 1999, fecal samples were collected from 669 beef cows on 39 farms located within 10 counties of ontario. overall prevalences of giardia, cryptosporidium muris, and cryptosporidium parvum in cows were 8.7%, 10.6%, and 18.4%, respectively. of the 39 farms sampled, giardia was detected on 64%, cr. muris on 72%, and cr. parvum on 90%. cryptosporidium parvum was detected in 28% of the cows in 1998 and in 5.2% in 1999. differences between the 2 y were attributed to sampling during calving ...	2005	15759828
prevalence of cryptosporidium parvum infection in southwestern ontario and its association with diarrhea in neonatal dairy calves.	cryptosporidium parvum infection was detected in 203 (40.6%) of 500 ontario dairy calves aged 7 to 21 d, on a convenience sample of 51 farms with a history of calf diarrhea. within-farm prevalence ranged from 0% to 70%, and both shedding and intensity of shedding were significantly associated with diarrhea. this parasite appears to be common in ontario dairy calves and important as a cause of dairy calf scours in the province.	2005	15943123
genotype and subtype analyses of cryptosporidium isolates from dairy calves and humans in ontario.	to assess the importance of dairy cattle as a source of human cryptosporidium infections in ontario, canada, 44 cryptosporidium isolates from neonatal dairy calves and 11 from sporadic human cases of cryptosporidiosis in the province were genotyped by pcr-rflp analyses of the cryptosporidium oocyst wall protein (cowp) and 18s rrna genes. isolates were also subtyped by sequence analysis of the 60-kda glycoprotein (gp60) gene. all bovine isolates successfully subtyped belonged to cryptosporidium p ...	2006	16565813
association between management practices and within-herd prevalence of cryptosporidium parvum shedding on dairy farms in southern ontario.	to identify management practices associated with an increased within-herd prevalence of cryptosporidium parvum shedding on dairy farms in southern ontario, fecal samples were taken from 1089 calves aged 7-28 days, from 119 herds. information on management practices was obtained by administering a questionnaire compiled using a modified delphi technique. data were analyzed using univariable and multivariable negative binomial regression. overall, 30% of the calves in the study were shedding c. pa ...	2008	17481752
calf-level risk factors for neonatal diarrhea and shedding of cryptosporidium parvum in ontario dairy calves.	this work was conducted to investigate calf-level factors that influence the risk of neonatal diarrhea and shedding of cryptosporidium parvum oocysts in calves, on dairy farms in ontario with histories of calf diarrhea or cryptosporidiosis. fecal samples were collected weekly for 4 weeks from each of 1045 calves under 30 days of age on 11 dairy farms in south-western ontario during the summer of 2003 and the winter of 2004. a questionnaire designed to gather information on calf-level management ...	2007	17602767
prevalence and molecular characterization of giardia duodenalis and cryptosporidium spp. in dairy cattle in ontario, canada.	giardia duodenalis and cryptosporidium spp. are intestinal protozoan parasites that infect a wide range of host species, including humans. molecular characterization of these parasites has demonstrated that a number of genotypes and species are common to both humans and animals, and that zoonotic transmission may occur. numerous studies have reported a high prevalence of g. duodenalis and cryptosporidium spp. in cattle, particularly calves, and these animals are frequently associated with zoonot ...	2007	17964724
the potential for zoonotic transmission of giardia duodenalis and cryptosporidium spp. from beef and dairy cattle in ontario, canada.	the objective of this study was to compare the occurrence and the genotypes and species of giardia duodenalis and cryptosporidium spp. in beef and dairy cattle from farms in the regional municipality of waterloo, ontario, in an effort to determine the potential for zoonotic transmission from these animals. pooled manure samples were collected from 45 dairy cattle farms and 30 beef cattle farms. the presence of giardia cysts and cryptosporidium oocysts was determined by immunofluorescence microsc ...	2010	20971563
detection and characterization of giardia duodenalis and cryptosporidium spp. on swine farms in ontario, canada.	abstract as part of the c-enternet surveillance program of the public health agency of canada, 122 pooled swine manure samples from 10 farms in ontario, canada were collected and tested for giardia and cryptosporidium. giardia duodenalis cysts and cryptosporidium spp. oocysts were detected using immunofluorescence microscopy. nested-polymerase chain reaction protocols were performed to amplify the small subunit rrna gene and the +¦-giardin gene for g. duodenalis, and the small subunit rrna gene ...	2011	21675863
molecular and phylogenetic approaches for assessing sources of cryptosporidium contamination in water.	the high sequence diversity and heterogeneity observed within species or genotypes of cryptosporidium requires phylogenetic approaches for the identification of novel sequences obtained from the environment. a long-term study on cryptosporidium in the agriculturally-intensive south nation river watershed in ontario, canada was undertaken, in which 60 sequence types were detected. of these sequence types 33 were considered novel with no identical matches in genbank. detailed phylogenetic analysis ...	2012	22841595
detection of cyclospora, cryptosporidium, and giardia in ready-to-eat packaged leafy greens in ontario, canada.	numerous foodborne outbreaks of diarrheal illness associated with the consumption of produce contaminated with protozoan parasites have been reported in north america in recent years. the present study reports on the presence of cyclospora, cryptosporidium, and giardia in precut salads and leafy greens purchased at retail in ontario, canada. a total of 544 retail samples were collected between april 2009 and march 2010 and included a variety of salad blends and individual leafy greens. most of t ...	2013	23433379