Animal Reservoirs of Shiga Toxin-ProducingEscherichia coli

Abstract

Shiga toxin-producing Escherichia coli (STEC) strains have been detected in a wide diversity of mammals, birds, fish, and several insects. Carriage by most animals is asymptomatic, thus allowing for dissemination of the bacterium in the environment without detection. Replication of the organism may occur in the gastrointestinal tract of some animals, notably ruminants. Carriage may also be passive or transient, without significant amplification of bacterial numbers while in the animal host. Animals may be classified as reservoir species, spillover hosts, or dead-end hosts. This classification is based on the animal's ability to (i) transmit STEC to other animal species and (ii) maintain STEC infection in the absence of continuous exposure. Animal reservoirs are able to maintain STEC infections in the absence of continuous STEC exposure and transmit infection to other species. Spillover hosts, although capable of transmitting STEC to other animals, are unable to maintain infection in the absence of repeated exposure. The large diversity of reservoir and spillover host species and the survival of the organism in environmental niches result in complex pathways of transmission that are difficult to interrupt.

Colonization of Enteroaggregative Escherichia coli and Shiga toxin-producing Escherichia coli in chickens and humans in southern Vietnam

“…The nondetection of STEC in chicken farms is in agreement with previous studies in chickens in the United States and United Kingdom in which the prevalence of STEC colonization ranged between 0 and 1.5 % [24]. Although we did not find the presence of STEC in chicken samples in this study, STEC is still an important cause of diarrhea in farm animals in Vietnam as has been shown in previous studies [25, 26].…”

Shiga Toxin–Producing E. coli Infections Associated with Flour

“…Some farmers use manure from cattle, a reservoir of STEC, to fertilize their wheat fields, which could lead to contamination of the wheat if the cattle are colonized. 20 Another source might be white-tailed deer, which are ubiquitous in the United States and are also reservoirs for STEC. 21 Given that a specific wheat field was not implicated in this investigation, we could not evaluate whether animal intrusion was a source of contamination.…”

Identification of Shiga toxin-producing (STEC) and enteropathogenic (EPEC) Escherichia coli in diarrhoeic calves and comparative genomics of O5 bovine and human STEC

“…The primary source of human infection is foodstuffs contaminated by the faeces of ruminants, especially cattle that can be healthy carriers in their intestinal tract. Numerous studies have been published about the prevalence of the carrier state, the incidence of faecal shedding and the virulotypes of AE-STEC present in asymptomatic cattle (Mekata et al, 2014;Beutin and Fach, 2015;Persad and Lejeune, 2015). Besides the O157: H7 serotype, that is the most frequently responsible for large outbreaks and the most pathogenic to humans, AE-STEC can belong to scores of serotypes (Tozzoli and Scheutz, 2014;Beutin and Fach, 2015).…”