Smouldering epidemic of Yersinia pseudotuberculosis in barn rats

Bacterial and viral rodent-borne infections on poultry farms. An attempt at a systematic review

Introduction

Rodents are quite common at livestock production sites. Their adaptability, high reproductive capacity and omnivorousness make them apt to become a source of disease transmission to humans and animals. Rodents can serve as mechanical vectors or active shedders of many bacteria and viruses, and their transmission can occur through direct contact, or indirectly through contaminated food and water or by the arthropods which parasitise infected rodents. This review paper summarises how rodents spread infectious diseases in poultry production.

Material and Methods

The aim of this review was to use PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) principles to meta-analyse the available data on this topic. Three databases – PubMed, Web of Science and Scopus – and grey literature were searched for papers published from inception to July 2022 using the established keywords.

Results

An initial search identified 2,999 articles that met the criteria established by the keywords. This number remained after removing 597 articles that were repeated in some databases. The articles were searched for any mention of specific bacterial and viral pathogens.

Conclusion

The importance of rodents in the spread of bacterial diseases in poultry has been established, and the vast majority of such diseases involved Salmonella, Campylobacter, Escherichia coli, Staphylococcus (MRSA), Pasteurella, Erysipelothrix or Yersinia infections. Rodents also play a role in the transmission of viruses such as avian influenza virus, avian paramyxovirus 1, avian gammacoronavirus or infectious bursal disease virus, but knowledge of these pathogens is very limited and requires further research to expand it.

Assessment of the Role of Free-living and Farmed Fallow Deer (Dama dama) as A Potential Source of Human Infection with Multiple-Drug-Resistant Strains of Yersinia enterocolitica and Yersinia pseudotuberculosis

Yersinia enterocolitica and Y. pseudotuberculosis are Gram-negative, facultative anaerobic bacteria that cause yersiniosis—one of the most important zoonotic diseases of the digestive tract. The aim of this study was to determine the prevalence of potentially human-pathogenic Y. enterocolitica and Y. pseudotuberculosis strains in free-living and farmed fallow deer, and to evaluate their sensitivity to chemotherapeutics. A total of 372 rectal swabs were analyzed, including 262 from free-living and 110 from farmed fallow deer. Due to the psychrophilic properties of Yersinia, two samples were collected from each animal. Seven Y. enterocolitica strains were isolated from free-living fallow deer, while two strains were isolated from farmed fallow deer. Yersinia pseudotuberculosis strains were not identified. All isolated Y. enterocolitica strains were ystB-positive, and phylogenetic analysis based on the nucleotide sequences of this gene revealed the presence of two phylogenetic groups. Yersinia enterocolitica strains isolated from fallow deer belonged to biotype 1A, and serotyping analysis demonstrated that the vast majority did not agglutinate with any diagnostic sera. All strains were multiple drug resistant and were not sensitive to at least four of the tested chemotherapeutics (amoxicillin with clavulanic acid, ampicillin, cefalexin, and streptomycin). One Y. enterocolitica strain isolated from a free-living animal was resistant to nine out of the 13 analyzed chemotherapeutics and was intermediately sensitive to the four remaining chemotherapeutics. The highest sensitivity was noted in case of ciprofloxacin (five strains) and trimethoprim-sulfamethoxazole (three strains). Only one strain isolated from a free-living animal was sensitive to three out of the 13 examined antibiotics, whereas the remaining strains were sensitive to only one drug or were not sensitive to any of the chemotherapeutics used. The results of this study indicate that multiple drug-resistant Y. enterocolitica strains can be carried by free-living and farmed fallow deer. This observation gives serious cause for concern because the meat of fallow deer and other ruminants is often consumed semi-raw (steak) or raw (tartar steak).

Genomic Epidemiology and Phenotyping Reveal on-Farm Persistence and Cold Adaptation of Raw Milk Outbreak-Associated Yersinia pseudotuberculosis

Packaged raw milk contaminated with Yersinia pseudotuberculosis mediated a large yersiniosis outbreak in southern Finland in 2014. The outbreak was traced back to a single dairy farm in southern Finland. Here we explore risk factors leading to the outbreak through epidemiologic investigation of the outbreak farm and through genomic and phenotypic characterization of the farm’s outbreak and non-outbreak associated Y. pseudotuberculosis strains. We show that the outbreak strain persisted on the farm throughout the 7-month study, whereas the non-outbreak strains occurred sporadically. Phylogenomic analysis illustrated that the outbreak strain was related to previously published genomes of wild animal isolates from Finland, implying that wild animals were a potential source of the outbreak strain to the farm. We observed allelic differences between the farm’s outbreak and non-outbreak strains in several genes associated with virulence, stress response and biofilm formation, and found that the outbreak strain formed biofilm in vitro and maintained better growth fitness during cold stress than the non-outbreak strains. Finally, we demonstrate the rapid growth of the outbreak strain in packaged raw milk during refrigerated storage. This study provides insight of the risk factors leading to the Y. pseudotuberculosis outbreak, highlights the importance of pest control to avoid the spread of pathogens from wild to domestic animals, and demonstrates that the cold chain is insufficient as the sole risk management strategy to control Y. pseudotuberculosis risk associated with raw drinking milk.

Low prevalence of human enteropathogenic Yersinia spp. in brown rats (Rattus norvegicus) in Flanders

Brown rats (Rattus norvegicus) have been identified as potential carriers of Yersinia enterocolitica and Y. pseudotuberculosis, the etiological agents of yersiniosis, the third most reported bacterial zoonosis in Europe. Enteropathogenic Yersinia spp. are most often isolated from rats during yersiniosis cases in animals and humans, and from rats inhabiting farms and slaughterhouses. Information is however lacking regarding the extent to which rats act as carriers of these Yersinia spp.. In 2013, 1088 brown rats across Flanders, Belgium, were tested for the presence of Yersinia species by isolation method. Identification was performed using MALDI-TOF MS, PCR on chromosomal- and plasmid-borne virulence genes, biotyping and serotyping. Yersinia spp. were isolated from 38.4% of the rats. Of these, 53.4% were designated Y. enterocolitica, 0.7% Y. pseudotuberculosis and 49.0% other Yersinia species. Two Y. enterocolitica possessing the virF-, ail- and ystA-gene were isolated. Additionally, the ystB-gene was identified in 94.1% of the other Y. enterocolitica isolates, suggestive for biotype 1A. Three of these latter isolates simultaneously possessed the ail-virulence gene. Significantly more Y. enterocolitica were isolated during winter and spring compared to summer. Based on our findings we can conclude that brown rats are frequent carriers for various Yersinia spp., including Y. pseudotuberculosis and (human pathogenic) Y. enterocolitica which are more often isolated during winter and spring.

Rodents on pig and chicken farms - a potential threat to human and animal health

Rodents can cause major problems through spreading various diseases to animals and humans. The two main species of rodents most commonly found on farms around the world are the house mouse (Mus musculus) and the brown rat (Rattus norvegicus). Both species are omnivorous and can breed year-round under favourable conditions. This review describes the occurrence of pathogens in rodents on specialist pig and chicken farms, which are usually closed units with a high level of bio-security. However, wild rodents may be difficult to exclude completely, even from these sites, and can pose a risk of introducing and spreading pathogens. This article reviews current knowledge regarding rodents as a hazard for spreading disease on farms. Most literature available regards zoonotic pathogens, while the literature regarding pathogens that cause disease in farm animals is more limited.

Vector competence of Musca domestica (Diptera: Muscidae) for Yersinia pseudotuberculosis

The vectoR potential of adult house flies. Musca domestica L., for Yersinia pseudotuberculosis (Pfeiffer), a pathogen of domestic animals and humans, was investigated. Adult flies were allowed to feed on trypticase soy broth (TSB) containing Y. pseudotuberculosis for 6 h and then transferred to sterile containers with sterile TSB as a source of water and nutrients. At 6-h intervals, all flies were transferred to sterile containers with sterile TSB and 10 randomly selected flies were examined for the pathogen. Yersinia pseudotuberculosis did not establish a permanent population in the house fly colony; however, viable cells were detected from the digestive tract of flies for up to 36 h after the initial exposure, and flies contaminated their environment (sterile TSB) for up to 30 h after the exposure. These results demonstrated that house flies can carry Y. psedotuberculosis for a considerable period and therefore must be considered as a potential mechanical vector of pseudotuberculosis infection.

Parasites of wild brown rats (Rattus norvegicus) on UK farms

Wild brown rats (Rattus norvegicus) from 11 rural UK farmsteads were found to carry 13 zoonotic and 10 non-zoonotic parasitic species, many of which (e.g. Cryptosporidium, Pasteurella, Listeria, Yersinia, Coxiella and Hantavirus) have rarely or never been previously investigated for wild rats. The study suggests that wild brown rats, serving as vectors of disease, represent a serious risk to the health of humans and domestic animals in the UK.

Plasmid DNA relatedness among different serogroups of Yersinia pseudotuberculosis

Thirteen different serogroup strains of Yersinia pseudotuberculosis and two strains of Yersinia enterocolitica O:3 were examined for the presence of plasmids and plasmid-mediated properties, calcium growth dependency, and autoagglutination. Two Y. enterocolitica strains and eight serogroup (IA, IIA, IIC, III, IVA, VB, VI, and VIII) strains, except for five serogroups (IB, IIB, IVB, VA, and VII), of Y. pseudotuberculosis harbored plasmids ranging in molecular size from 27 to 115 kilobases. Filter hybridization of restriction endonuclease-digested plasmid DNA from different serogroup strains indicated that all plasmid DNAs conferring calcium growth dependency and autoagglutination shared a high degree of DNA sequence homology, regardless of the different serogroups of Y. pseudotuberculosis and Y. enterocolitica.

Prospective systematic study of Yersinia spp. in dogs

A total of 93 Yersinia spp. were isolated from 68 of 252 dogs in Shimane Prefecture, Japan. The Yersinia spp. were 70 Yersinia enterocolitica isolates from 50 dogs, 2 Yersinia frederiksenii isolates from 2 dogs, 5 Yersinia intermedia isolates from 5 dogs, and 16 Yersinia pseudotuberculosis isolates from 16 dogs. Fifteen of 70 Y. enterocolitica isolates belonged to biotype 4 serotype O3 phagotype 8 (6 isolates), biotype 4 (maltose negative) serotype O3 phagotype 8 (4 isolates), biotype 3 (Voges-Proskauer and sorbose negative) serotype O3 phagotype 9 (2 isolates), and biotype 2 serotype O5.27 (3 isolates). The other 55 Y. enterocolitica isolates belonged to biotype 1 and were classified into serotypes O4, O5, O7 .8, O9, O10 , O12 , O13 .7, O14 , O15 , and untypable. Sixteen Y. pseudotuberculosis isolates belonged to serotypes IB (two), IIB (two), IVA (two), IVB (three), VA (five), and untypable (two). These isolates were mostly detected in cold months. Y. enterocolitica serotype O3 and Y. pseudotuberculosis were isolated more frequently from puppies. Y. enterocolitica serotype O3 was recovered at less than 10(7.0) cells per g of the jejunal-to-rectal contents and at less than 10(2) cells per g of mesenteric lymph nodes. Y. pseudotuberculosis was recovered at less than 10(4.3) cells per g of the cecal-to-rectal contents and at less than 10(2.9) cells per g of mesenteric lymph nodes. Almost all strains of Y. enterocolitica biotype 1, Y. intermedia, and Y. frederiksenii were recovered at less than 10(2) cells per g of gastric-to-rectal contents.

Isolation of Yersinia spp. from bovine feces

Yersinia spp. were sought in 618 fecal samples from cows. Four strains of Yersinia enterocolitica, serotype O:12,26 (one), O:13,7 (two), and O:18 (one); seven strains of Yersinia kristensenii, serotype O:11,24 (five) and O:12,26 (two); and one strain of Yersinia pseudotuberculosis serotype IIB, were isolated. This is the first time that Y. pseudotuberculosis has been isolated from cows in Japan, and the isolation of serotype IIB of this organism from cows seems to be the first in the world.

Cross-protection against fecal excretion of Yersinia enterocolitica and Yersinia pseudotuberculosis in mice by oral vaccination of viable cells

Mice given orally either the O3, O9, or O5B serovar of Yersinia enterocolitica showed protection upon subsequent oral challenge with another of these strains. Excretion of serovar O3 in the feces was inhibited in mice surviving oral challenge with Yersinia pseudotuberculosis IVA. Cross-reaction of O antigen among these four strains was 32 or more times lower than the homologous titers.

Occurrence of Yersinia enterocolitica in wild animals

Yersinia species were isolated from 16 of 495 small wild animals and from 1 of 38 foxes. The animals were trapped in seven regions of Hokkaido, Japan. Of the 17 strains isolated, 9 were Yersinia enterocolitica O6; 2 were Y. enterocolitica O5A; 1 was Y. enterocolitica, O4; 1 was Y. enterocolitica O9; 1 was Yersinia pseudotuberculosis IVB; and 3 were sucrose-negative strains. Yersinia pestis was not isolated. The O6 organism was most prevalent in large red-back mice (Clethrionomys rufocanus bedfordiae) and showed significant differences in its mode of distribution according to region. Incidence of the O6 organism in the ileum of the animal was threefold that in the cecum, and the organism was recovered at approximately 10(5) cells per g of cecal contents per c. rufocanus bedfordiae animal.