Risk of Yersinia infection among butchers

An Update in Knowledge of Pigs as the Source of Zoonotic Pathogens

The available data indicate that the human world population will constantly grow in the subsequent decades. This constant increase in the number of people on the Earth will lead to growth in food demand, especially in food of high nutritional value. Therefore, it is expected that the world livestock population will also increase. Such a phenomenon enhances the risk of transmitting pathogens to humans. As pig production is one of the most significant branches of the world's livestock production, zoonoses of porcine origins seem to be of particular importance. Therefore, in this review, we aim to introduce the latest data concerning, among other things, epidemiology and available preventive measures to control the most significant porcine zoonoses of viral, bacterial, and parasitic origin.

Attenuation and preserved immunogenic potential of Yersinia pseudotuberculosis mutant strains evidenced in oral pig model

Experimental oral infection of pigs with a parental Yersinia pseudotuberculosis strain pIB102, serotype O:3 and two mutant isogenic strains - pIB155,DeltayopK and pIB44,DeltaypkA has been carried out. Clinical findings, microbiological and immunological parameters were examined in dynamics from day 7 to day 60 post-infection (p.i.). All types of infections ran asymptomatically, without hyperthermia, loss of appetite, etc. Experiments on the blood parameters demonstrated a transient leucocytosis with lymphocytosis and monocytosis better expressed after yopK infection. Even though pig is usually known as a reservoir of yersiniae, bacterial colonization was found in mesenterial lymph nodes and tonsils on day 7, respectively 14 p.i. with parental strain, and only in tonsils on day 14 p.i. with both mutant strains. The augmented sensitivity of mutants to the bactericidal effect of leukocytes and blood sera is the characteristic feature of attenuation in their pathogenicity, compared to the parental strain. Comparative in vitro experiments on the immune response and immunostimulating capacity of Y. pseudotuberculosis mutant strains verify their preserved immunogenic potential, predominantly in case of yopK. Hyperplasia and strong activation of the lymph tissue of Peyer's patches, mesenterial lymph nodes, tonsils and spleen of pigs challenged with both mutant strains were proved as immunomorphological rearrangements. The results obtained give the reason to claim that the genetically constructed yopK null mutant strain is significantly attenuated but is still immunogenic and has the potential for a live vaccine carrier strain.

Lack of cross-species transmission of porcine endogenous retrovirus (PERV) to transplant recipients and abattoir workers in contact with pigs

This study investigated the potential transmission of porcine endogenous retrovirus (PERV) to solid-organ transplant recipients and abattoir workers in contact with pigs. Blood samples were obtained from volunteer healthy blood donors (Group A; n=33); pig-breeding farmers who had undergone a liver transplant (Group B; n=14); and pig abattoir workers (Group C; n=49). A second blood sample was obtained 1 year after the first sample from 10 of the abattoir workers (Group D). Tests included investigation for PERV-DNA, PERV-RNA, pig-specific mitochondrial DNA, a quantitative detection of PERV nucleic acids, and antibodies to PERV by two different Western Blots. All polymerase chain reaction and Western Blots assays were negative for PERV or antibodies to PERV. Therefore, the risks of cross-species transmission of PERV appear to be negligible for immunocompetent individuals and allotransplant recipients, even if they are in close and repeated contact with live pigs or pig tissues.

Reactive arthritis or post-infectious arthritis?

The term 'reactive arthritis' was first used in 1969 to describe the development of sterile inflammatory arthritis as a sequel to remote infection, often in the gastrointestinal or urogenital tract. The demonstration of antigenic material (e.g. Salmonella and Yersinia lipopolysaccharide), DNA and RNA, and, in occasional cases, evidence of metabolically active Chlamydia spp. in the joints has blurred the boundary between reactive and post-infectious forms of arthritis. No validated and generally agreed diagnostic criteria exist, but the diagnosis of reactive arthritis is mainly clinical based on acute oligoarticular arthritis of larger joints that develops within 2-4 weeks of the preceding infection. In about 25% of patients, the infection can be asymptomatic. Diagnosis of the triggering infection is very helpful for the diagnosis of reactive arthritis. This is mainly achieved by isolating the triggering infection (stools, urogenital tract) by cultures (stool cultures for enteric microbes) or ligase reaction (Chlamydia trachomatis). However, after the onset of arthritis, this is less likely to be possible. Therefore, the diagnosis must rely on various serological tests to demonstrate evidence of previous infection, but, these serological tests are unfortunately not standardized. Treatment with antibiotics to cure Chlamydia infection is important, but the use of either short or prolonged courses of antibiotics in established arthritis has not been found to be effective for the cure of arthritis. The long-term outcome of reactive arthritis is usually good; however, about 25-50% of patients, depending on the triggering infections and possible new infections, subsequently develop acute arthritis. About 25% of patients proceed to chronic spondyloarthritis of varying activity.

Antimicrobial antibodies in Danish slaughterhouse workers and greenhouse workers

As a consequence of contact with animals and animal products slaughterhouse workers might be at risk of infection with pathogenic microorganisms. This hypothesis has been supported by some earlier studies. In this study 217 slaughtermen and a control group of 113 greenhouse workers were investigated for the prevalence of serum antibodies to Toxoplasma gondii, Campylobacter jejuni (IgA and IgG), Yersinia enterocolitica types 3 and 9, Yersinia pseudotuberculosis types I, II, III, IV, and V, Salmonella typhi, Salmonella paratyphi, Salmonella enteritidis, Salmonella typhimurium, and Borrelia burgdorferi. No significant differences were found concerning either frequency of positive tests or magnitude of titers. The prevalence of toxoplasma antibodies was remarkably high in both groups.

Increased yields of pathogenic Yersinia enterocolitica strains by cold enrichment

Yersinia strains recovered from routine stool cultures (n = 13,534) as well as clinical symptoms in the patients were analysed in order to establish whether enteric Yersinia enterocolitica strains recovered only after cold enrichment cultures shared the same pathogenicity markers and caused the same symptoms as strains from primary cultures. 93% of the 201 Yersinia isolates were Y. enterocolitica strains and 71% of these were of serotype O3. Nearly 40% of all Y. enterocolitica strains and 21% of serotype O3 strains were isolated only after 1 week's cold enrichment of stool specimens. Practically all Y. enterocolitica O3 strains, whether from primary or cold enrichment cultures, were pathogenic not only on the basis of the serotype but also on the basis of Congo-red uptake and calcium-dependent growth at 35 degrees C (CR-MOX test). The symptoms in patients with Y. enterocolitica O3 from primary and cold enrichment cultures were similar except that abdominal pains were more frequent (p < 0.05) in the former. Arthropathia, mesenteric lymphadenitis and erythema nodosum were detected in 15% of the patients with Yersinia isolates and were more frequent in patients with isolates from cold enrichment or without diarrhea.

Possible confounders of the relationship between occupational swine contact and Yersinia enterocolitica 0:3 and 0:9 antibodies

Increased risk of high Yersinia enterocolitica 0:3 and 0:9 antibody content has been previously reported in occupations with swine contact. In this study several possible confounders of this elevated risk among pig farmers and abattoir workers were considered. Only in three instances the standardized risk ratio was decreased close to unity, namely after the standardization of Y. enterocolitica 0:3 IgG antibody positivity for age among abattoir workers, after the standardization of Y. enterocolitica 0:9 IgG antibody positivity for farm butchering among pig farmers and for smoking among abattoir workers. As the decrease did not apply for both pig farmers and abattoir workers and for both 0:3 and 0:9 serotypes considered, it seems reasonable to assume that the three decreases represent products of multiple testing inherent in this kind of search of confounders rather than any true effects. In view of the present knowledge on the determinants of yersinia antibodies in populations, the crude risk ratios for elevated yersinia antibodies can be held to be reasonably unconfounded.