Prevalence and risk indicators associated with Salmonella infection in farrow-to-finish farm in Reunion Island

Abstract

Salmonella is the second cause of foodborne diseases in France and pork products are regularly incriminated. For the implementation of control measures in farms, it is necessary to better understand the risks of infection of pigs by Salmonella at farms. Our epidemiological study aims to determine Salmonella prevalence of fattening pigs in Reunion Island, oversea territory of France, and the main risk indicators for pig infection. Fifty farms (farrow-to finish and multiplier) were randomly selected and visited 4 times: at slaughtered previous batch, after cleaning and disinfection, beginning and end of the fattening period for the studied batch. Pools of fresh faeces, gauze socks and gauze swabs were sampled to assess the bacteriological status of these pig farms. A questionnaire was submitted to farmers and analysed for the further identification of risk indicators. Thirty-nine farms (78% IC95% [68.3-87.6]) were tested positive for Salmonella. High prevalence of Salmonella may be related to poor decontamination.

Wild fauna as a carrier of Salmonella in Reunion Island: Impact on pig farms

“…The serotype S. 4,[5],12:i:-was the most predominant, and was isolated from birds, rodents and cockroaches confirming a broad distribution of this serotype within Reunion Island's wild fauna. Despite the predominance could be explained by our sampling strategy, these results could also be related to the emergence of this serotype in the pig and poultry production in Reunion Island (Tessier et al, 2013a;Tessier et al, 2013b;Henry et al, 2015;Cardinale et al, 2010) .This observation is in contrast with other studies, which have scarcely detected S. 4,[5],12:i:-in wild animal communities (Andres-Barranco et al, 2014;Smith et al, 2002). In Europe also, S. 4,[5],12:i:-has emerged over the last two decades (EFSA Panel on Biological Hazards (BIOHAZ), 2010) and was the third most frequently reported serotype in human salmonellosis in 2012 (EFSA and ECDC, 2014).…”

“…The observed elevated prevalence may result from sample pooling, which has been shown to be optimal for Salmonella detection however but this result is not indicative of individual infection of cockroaches (Arnold et al, 2005;Arnold et al, 2014). Furthermore, all samples were collected from pig farms across Reunion Island, where presence of Salmonella is known to be frequent (Cardinale et al, 2010;Tessier et al, 2013b).…”

“…For the genotypic comparison, we considered one isolate per PFGE profile and per sample collected from wild birds, small mammals and cockroaches. We also considered Salmonella isolates collected from Salmonella-positive pig farms (pool of faeces or pair of gauze socks of pens) investigated during the same period (Tessier et al, 2013b). Out of these 50 investigated pig farms, a collection of 127 isolates was taken into account, still considering one isolate per PFGE profile and per farm.…”

“…The 127 isolates selected from pig faeces and pen floors in pig farms in Reunion Island (Tessier et al, 2013b) were distributed into 83 XbaI profiles. Fourteen XbaI profiles (36 isolates)…”

“…However, it is known that human salmonellosis is under-estimated in this small French overseas department (D'Ortenzio et al, 2008). Furthermore, prevalence of Salmonella in pig farms has been reported as being particularly high in Reunion Island: with more than 60% of pig batches being infected with this pathogen towards the end of the fattening period (Cardinale et al, 2010;Tessier et al, 2013b).…”