Tracing the Source of Campylobacteriosis

Abstract

Campylobacter jejuni is the leading cause of bacterial gastro-enteritis in the developed world. It is thought to infect 2–3 million people a year in the US alone, at a cost to the economy in excess of US $4 billion. C. jejuni is a widespread zoonotic pathogen that is carried by animals farmed for meat and poultry. A connection with contaminated food is recognized, but C. jejuni is also commonly found in wild animals and water sources. Phylogenetic studies have suggested that genotypes pathogenic to humans bear greatest resemblance to non-livestock isolates. Moreover, seasonal variation in campylobacteriosis bears the hallmarks of water-borne disease, and certain outbreaks have been attributed to contamination of drinking water. As a result, the relative importance of these reservoirs to human disease is controversial. We use multilocus sequence typing to genotype 1,231 cases of C. jejuni isolated from patients in Lancashire, England. By modeling the DNA sequence evolution and zoonotic transmission of C. jejuni between host species and the environment, we assign human cases probabilistically to source populations. Our novel population genetics approach reveals that the vast majority (97%) of sporadic disease can be attributed to animals farmed for meat and poultry. Chicken and cattle are the principal sources of C. jejuni pathogenic to humans, whereas wild animal and environmental sources are responsible for just 3% of disease. Our results imply that the primary transmission route is through the food chain, and suggest that incidence could be dramatically reduced by enhanced on-farm biosecurity or preventing food-borne transmission.

Campylobacteriosis: an emerging zoonosis, underdiagnosed and underreported by public health agencies in Brazil

“…Despite reported decrease in the number of positive samples during the slaughtering process steps studied were not able to guarantee the food safety. Wilson et al (2008) indicated for control of meat contamination by animal feces, equipment sterilization and additional care when handling the animals with positivity. The authors believe that the primary route of Campylobacter spp.…”

Campylobacter sequence typing databases: applications and future prospects

“…A number of studies have isolated Campylobacter strains that were indistinguishable by MLST from broiler flocks and their environment, including areas of housing, drinking water, puddles and nearby cattle (Ogden et al, 2007;Patriarchi et al, 2011). Large population-based studies, however, indicate that while certain clonal complexes, for example the ST-21 and ST-45 complexes, are able to colonize multiple host sources, the majority of Campylobacter isolates from broiler flocks are characteristically 'chicken-associated' and can be differentiated from ruminant and environmental strains (McCarthy et al, 2007;Mullner et al, 2009b;Sheppard et al, 2009b;Wilson et al, 2008) (Table 1). Campylobacter genotypes isolated from non-agricultural sources, such as wild birds and mammals, or from environmental waters that are not contaminated by agricultural run-off, are found only rarely among broiler flock isolates (Griekspoor et al, 2010).…”

“…This is an essential prerequisite for the design of effective interventions to reduce the incidence of human disease. A number of different genetic attribution models have been developed and employed with MLST data: (i) the Dutch model (Mullner et al, 2009b); (ii) the modified Hald model (Mullner et al, 2009a); (iii) STRUCTURE (Falush et al, 2003;Pritchard et al, 2000); (iv) the Asymmetrical Island (AI) model (Wilson et al, 2008), and (v) the Bayesian Analysis of Population Structure (BAPS) model (Corander & Marttinen, 2006). The Dutch and modified Hald models are based on comparing the number of human cases of disease caused by a Campylobacter subtype, relative to the proportional occurrence of particular subtypes in each potential host source (Mullner et al, 2009b The results from these methods using data from Scotland, north-west England and New Zealand were in agreement that strains isolated from chickens, and in particular chicken meat, were the most similar to those isolated from human disease (Gormley et al, 2008;Mullner et al, 2009b;Sheppard et al, 2009b).…”

Campylobacter jejuniisolated from human cases in Chile showed indistinguishable pulsed field gel electrophoresis profiles with strains isolated from poultry and bovine sources

“…Human infections can be acquired from various sources specially water and unpasteurized milk (Wilson et al, 2008) but the consumption of contaminated poultry, particularly fresh broiler meat, has been considered as the most prevalent cause of gastroenteritis in Europe (EFSA, 2011).…”