Modelling the vector pathway and infection of humans in an environmental outbreak of Escherichia coli O157

Strachan, Norval James Colin

doi:10.1016/s0378-1097(01)00342-1

Cited by 38 publications

(68 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, once faeces have become mixed with soil, ingestion is more likely. The model developed in this paper, assumes that the faeces is mixed homogeneously in the top 1 cm of soil which is in broad agreement with the experimental results (Fenlon et al, 2000;Strachan et al, 2001).…”

Section: Concentration On the Pasturesupporting

confidence: 72%

“…The two dose -responses are considerably different with the rabbits requiring approximately 500-fold more organisms to cause 50% infection compared with the human data. In the current study, the surrogate Shigella dose -response model has been selected because it closely fits the outbreak in scouts at New Deer (Strachan et al, 2001) and appears to be closer to other recorded outbreak data (Ogden and Strachan, data not presented). The format of the model used is as described in Cassin et al (1998) and is given in Table 4.…”

Section: Hazard Characterisation/dose-response Assessmentmentioning

confidence: 95%

“…These North American data (Zhao et al, 1995;Shere et al, 1998) may be quite different to shedding rates in Scotland and throughout the UK. In the UK, it has been shown that sheep can shed up to the range of 10 6 -10 7 CFU/g (Strachan et al, 2001) while in Australia total shiga-toxin producing E. coli in cattle can shed at levels approaching 10 7 CFU/g (Vanderlinde, 2001). Therefore, the risk assessment was run for a range of scenarios of animals shedding between 10 1 and 10 7 CFU/g.…”

Section: Prevalencementioning

confidence: 99%

“…A recent outbreak in a scout camp which took place on a pasture previously grazed by sheep at New Deer, North East Scotland resulted in 18 of the 226 scouts falling ill (Anonymous, 2000;Grampian Health Board, 2000). A point source outbreak arising from the sheep was suspected and E. coli O157 was isolated from samples of soil, standing water and sheep faeces taken from the field during the week following the outbreak (Strachan et al, 2001). The likely route of transmission was via hands contaminated with mud and faecal material.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Quantitative risk assessment of human infection from Escherichia coli O157 associated with recreational use of animal pasture

Strachan

Dunn

Ogden

2002

International Journal of Food Microbiology

View full text Add to dashboard Cite

A quantitative microbial risk assessment incorporating Monte Carlo simulations is described which estimates the probability of Escherichia coli O157 infection of humans by visiting pasture previously grazed by cattle. The risk assessment is performed for a number of scenarios including a variation in the grazing period prior to the human visit, the duration of visit (8-h day or 24-h camp) and the level of E. coli O157 shed by the cattle. Assuming the cattle have been on the field for 28 days, followed directly by a human visit, and the proportion of animals shedding the organism are as described in previous surveys 5 F 1% (Synge, B.A., Gunn, G.J., Ternent, H.E., Hopkins, G.F., Thomson-Carter, F., Foster, G., Chase-Topping, M., McKendrick, I., 2001). Prevalence and factors affecting the shedding of verocytotoxin producing Escherichia coli O157 in beef cattle in Scotland. In: Concerted Action CT98-3935 Veroctotoxigenic E. coli in Europe, 5. Epidemiology of Verocytotoxigenic E. coli, Dublin, pp. 98 -103.), a probability of infection of 0.1% is attained for 8-and 24-h periods when the cattle are shedding approximately 10 3 and 10 4 CFU g À 1 , respectively. Monte Carlo simulations demonstrated that risk mitigation strategies of removing cattle from the pasture 4 weeks prior to the human visit in addition to physical removal of faeces showed significant reductions in potential infection rates. D

show abstract

Section: Concentration On the Pasturesupporting

confidence: 72%

Section: Hazard Characterisation/dose-response Assessmentmentioning

confidence: 95%

Section: Prevalencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quantitative risk assessment of human infection from Escherichia coli O157 associated with recreational use of animal pasture

Strachan

Dunn

Ogden

2002

International Journal of Food Microbiology

View full text Add to dashboard Cite

show abstract

“…Examples of where infection has been specifically associated with sheep include: illness linked with lambing ewes (Allison et al, 1997); sheep faeces apparently contaminating the water supply at a campsite outbreak (Licence et al, 2001); and an outbreak at a boy-scout camp caused through contact with sheep faeces (Strachan et al, 2001). Though sheep have been proposed as sources for human infection on a number of occasions, there have been few prevalence studies of verocytotoxigenic E. coli in sheep.…”

Section: Introductionmentioning

confidence: 99%

Prevalence of Escherichia coli O157 : H7 and serogroups O26, O103, O111 and O145 in sheep presented for slaughter in Scotland

Evans

Knight

McKendrick

et al. 2011

Journal of Medical Microbiology

View full text Add to dashboard Cite

Sheep have been proposed as a source of human verocytotoxigenic Escherichia coli infection on a number of occasions but few prevalence studies have focused on identifying rates of carriage of these pathogens in this species. The purpose of this work was to establish the frequency of excretion of E. coli of serogroups O157, O26, O103, O111 and O145 in sheep presented for slaughter in Scotland and to examine their carriage of known virulence determinants. The study involved microbiological isolation of E. coli from 1082 sheep presented for slaughter in four Scottish abattoirs between July 2005 and June 2006. Using faecal enrichment and immunomagnetic separation, the isolation rate from these samples was 3.4 % for E. coli serogroup O157, 5.2 % for E. coli serogroup O26, 2.3 % for E. coli serogroup O103 and 0.1 % for E. coli serogroup O145. E. coli O111 was not isolated. In the last month of testing, which coincided with sorbitol-fermenting E. coli O157 (SFO157) cases in children in Scotland, all 83 recta received were screened and tested negative for SFO157 strains. The study found no verocytotoxin-positive strains amongst the E. coli serogroup O103 or O145 isolates. Verocytotoxin-positive strains were identified amongst isolates of E. coli serotypes O157 : H7 and O26 : H11. E. coli O157 : H7 was not isolated from samples collected between January and March, a statistically significant drop (P,0.001) in mean shedding relative to other months. There was evidence (P50.003) of higher shedding of O157 in adults and hoggs than in lambs. E. coli O26 : H11 was isolated throughout the year, with a statistically significant peak in shedding in the third quarter (P50.003). The results showed that sheep presented for slaughter in Scotland may carry strains of E. coli, particularly of serogroups O157 and O26, which can be presumed to have potential to cause human infection. They did not support a hypothesis that human cases of E. coli O157 : H7 are higher in any particular Scottish region as a direct consequence of a higher rate of faecal carriage in sheep in that region. INTRODUCTIONEscherichia coli strains that produce verocytotoxins are important pathogens causing human illnesses ranging from diarrhoea to haemorrhagic colitis and haemolytic uraemic syndrome (Karmali, 1989;Riley, 1987). In the UK, North America, Japan and much of continental Europe, such disease is commonly caused by E. coli strains of serogroup O157 (Riley et al., 1983;Kleanthous et al., 1990;Willshaw et al., 2001;Kaper et al., 2004;Chase-Topping et al., 2008).A variety of infection routes, including food-borne transmission and person-to-person spread, have been described, but in the UK, human infections by E. coli O157 are also recognized arising from direct contact with animal reservoirs (Locking et al., 2001;O'Brien et al., 2001). Examples of where infection has been specifically associated with sheep include: illness linked with lambing ewes (Allison et al., 1997); sheep faeces apparently contaminating the water supply at a campsite outbreak (Licence et...

show abstract

Investigation of an outbreak of Escherichia coli O157 infection caused by environmental exposure at a scout camp

et al. 2003

View full text Add to dashboard Cite

In May 2000 a scout camp was held on an agricultural showground in New Deer, Aberdeenshire. There were 337 campers at the event, comprising 233 cubs, scouts, and venture scouts, and 104 adults. The event was abandoned early because of heavy rainfall. Twenty campers who became ill between 28 May and 3 June were confirmed as having E. coli O157 infection. Preliminary investigation did not suggest a food vehicle but did indicate environmental exposure at the camp as a risk factor. Subsequent investigations supported the hypothesis that transmission of E. coli O157 was from the environment to cases by contaminated hands, either directly from hand to mouth, or via food. As a result of the investigation the Aberdeenshire Council and the Scout Association jointly prepared interim guidelines to reduce the risk of E. coli O157 infection at scout camps.

show abstract

Modelling the vector pathway and infection of humans in an environmental outbreak of Escherichia coli O157

Cited by 38 publications

References 13 publications

Quantitative risk assessment of human infection from Escherichia coli O157 associated with recreational use of animal pasture

Quantitative risk assessment of human infection from Escherichia coli O157 associated with recreational use of animal pasture

Prevalence of Escherichia coli O157 : H7 and serogroups O26, O103, O111 and O145 in sheep presented for slaughter in Scotland

Investigation of an outbreak of Escherichia coli O157 infection caused by environmental exposure at a scout camp

Contact Info

Product

Resources

About