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In Sweden, 2 tick-borne zoonotic diseases, granulocytic ehrlichiosis and borreliosis, are frequently diagnosed in dogs, using serological assays. The aims of this study were to determine the sero-prevalences of antibodies to Ehrlichia spp. and Borrelia burgdorferi sensu lato during 1991-94 in dogs, not clinically suspected to be infected with either of the 2 agents. Samples (n = 611) were selected from a serum bank using a systematic sampling strategy, stratified across the 4-y period. The stored sera had originally been submitted in order to verify or rule out infection with Sarcoptes scabiei. The overall sero-prevalence for Ehrlichia spp. was 17.7% and for Borrelia burgdorferi sensu lato 3.9% (n = 588). Only a few dogs in the northern part of Sweden were sero-positive for Ehrlichia spp. and none were positive for Borrelia burgdorferi sensu lato. An increased sero-prevalence of Ehrlichia spp. was seen during the years studied. The sero-prevalence of Ehrlichia spp. varied with season. Sero-positivity to both agents increased with age. Both diseases are considered zoonotic, and the increase in sero-prevalence of Ehrlichia spp. over the years may reflect the degree of infection in ticks and may have implications for human health. [ABSTRACT FROM AUTHOR]

Intradermal administration of glutaraldehyde-fixed Aujeszky's disease virus (ADV) infected autologous or allogeneic cells resulted in the induction of an interferon(IFN)-α response in pigs. Using a sensitive dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA), IFN-α was detected in blood at 8 and 24 h after injection of ADV-infected cells. In parallel, by means of in situ hybridization, IFN-α/β mRNA containing cells were demonstrated in regional lymph nodes. Occasional IFN-α/β mRNA positive cells were also seen in injected dermal areas, but not in contralateral lymph nodes, spleen, bone marrow, blood or liver. The ability of leucocytes in whole blood cultures to produce IFN-α upon stimulation by ADV was markedly diminished 3-7 days after intradermal injection of ADV-infected cells. In contrast, cultures of purified peripheral blood mononuclear cells (PBMC) had intact IFN-α responses. Further, serum from ADV-injected pigs inhibited the in vitro ADV-induced IFN-α responses in PBMC from control pigs, most likely due to the demonstrated presence of anti-ADV antibodies. We suggest that the IFN-α/β producing cells in lymph nodes may participate in the development of antiviral immunity and could be equivalent to Natural IFN-α/β producing (NIP) cells. [ABSTRACT FROM AUTHOR]

Abstract Backgroud Anaplasma phagocytophilum (formerly Ehrlichia phagocytophila) causes the disease tick-borne fever (TBF) in domestic ruminants and has for decades been one of the main scourges for the sheep industry in the coastal areas of Norway. Current control strategies are based on reduction of tick infestation by chemical acaricides. Methods In the present study, we investigated if frequent pour-on applications of pyrethroids would reduce tick infestion rate and seroprevalence of A. phagocytophilum infection in sheep. Forty lambs, one month old, of the Norwegian White Sheep breed were used. The lambs belonged to the experimental sheep flock at the Department of Production Animal Clinical Sciences. None of the lambs had been on I. ricinus infested pasture before turnout (day 0). All lambs were twins and twenty lambs were treated with a pour-on pyrethroid (Bayticol®, Bayer A/S, DK-2300) with a dose of 5 ml on days 0, 14, 28, 42, 56, 70, 84, 98, 112 and 128. Twenty lambs were untreated controls. The lambs were collected every fourteen days on pasture for treatment. In addition, the lambs were examined for ticks, blood sampled, weighed, and rectal temperature was recorded. Results and conclusion A significant reduction in tick infestion rate was detected on treated lambs. However, the present results indicate that frequent acaricide treatment does not reduce the seroprevalence to A. phagocytophilum on tick-infested pasture.

Abstract Background Dairy cattle were used as sentinels for the presence of Leptospira infection in Swedish livestock in four regions contrasting in precipitation and temperature during the summer time. The aim of the study was to estimate the prevalence of five serovars of Leptospira of low pathogenicity in dairy cattle in these four regions. Findings Around 150 blood samples were collected from five dairy farms from each region, making 610 samples in total, during December 2009. The samples were screened for L. kirschneri sv Grippotyphosa, L. interrogans sv Icterohaemorrhagiae, L. interrogans sv Canicola, L. borgpetersenii sv Sejroe and one domestic strain similar to sv Sejroe, called strain Mouse 2A using the Microscopic Agglutination Test. Six animals (1%) were seropositive for the strain Mouse 2A. Four of the positive samples were from the south-west region which also was the region with highest precipitation. There were no positive samples to any of the other serovars studied. Conclusions The present data indicate that there is a low seroprevalence of Leptospira in Swedish dairy cows. These findings can be used as baseline data to investigate the effects of, for instance, climatic change or alterations in wildlife reservoir populations on the seroprevalence of Leptospira in the future.

The application of a One Health approach recognizes that human health, animal health, plant health and ecosystem health are intrinsically connected. Tackling complex challenges associated with foodborne zoonoses, antimicrobial resistance, and emerging threats is imperative. Therefore, the One Health European Joint Programme was established within the European Union research programme Horizon 2020. The One Health European Joint Programme activities were based on the development and harmonization of a One Health science-based framework in the European Union (EU) and involved public health, animal health and food safety institutes from almost all EU Member States, the UK and Norway, thus strengthening the cooperation between public, medical and veterinary organizations in Europe. Activities including 24 joint research projects, 6 joint integrative projects and 17 PhD projects, and a multicountry simulation exercise facilitated harmonization of laboratory methods and surveillance, and improved tools for risk assessment. The provision of sustainable solutions is integral to a One Health approach. To ensure the legacy of the work of the One Health European Joint Programme, focus was on strategic communication and dissemination of the outputs and engagement of stakeholders at the national, European and international levels.

Introduction: The awareness of scientists and policy makers regarding the requirement for an integrated One Health (OH) approach in responding to zoonoses has increased in recent years. However, there remains an overall inertia in relation to the implementation of practical cross-sector collaborations. Foodborne outbreaks of zoonotic diseases continue to affect the European population despite stringent regulations, evidencing the requirement for better 'prevent, detect and response' strategies. Response exercises play an essential role in the improvement of crisis management plans, providing the opportunity to test practical intervention methodologies in a controlled environment., Methods: The One Health European Joint Programme simulation exercise (OHEJP SimEx) aimed at practicing the OH capacity and interoperability across public health, animal health and food safety sectors in a challenging outbreak scenario. The OHEJP SimEx was delivered through a sequence of scripts covering the different stages of a Salmonella outbreak investigation at a national level, involving both the human food chain and the raw pet feed industry., Results: A total of 255 participants from 11 European countries (Belgium, Denmark, Estonia, Finland, France, Italy, Norway, Poland, Portugal, Sweden, the Netherlands) took part in national level two-day exercises during 2022. National evaluations identified common recommendations to countries aiming to improve their OH structure to establish formal communication channels between sectors, implement a common data sharing platform, harmonize laboratory procedures, and reinforce inter-laboratory networks within countries. The large proportion of participants (94%) indicated significant interest in pursuing a OH approach and desire to work more closely with other sectors., Discussion: The OHEJP SimEx outcomes will assist policy makers in implementing a harmonized approach to cross-sector health-related topics, by highlighting the benefits of cooperation, identifying gaps in the current strategies and suggesting actions required to better address foodborne outbreaks. Furthermore, we summarize recommendations for future OH simulation exercises, which are essential to continually test, challenge and improve national OH strategies., Competing Interests: The authors declare that the OHEJP SimEx project was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Alves, Artursson, Bloch, Brisabois, Imberechts, Jokelainen, La Ragione, Lindblad, Forss, Marston, Parvizi, Tuominen and Omazic.)

Whole-genome sequencing was carried out on 30 Staphylococcus (S.) aureus isolates from dairy cows with subclinical mastitis from all five provinces of Rwanda. Twenty-five of the isolates produced enough sequence to be analyzed using core genome multilocus sequence typing (cg-MLST). The isolates group into three main clusters. The largest cluster contain isolates of sequence type (ST) 152 ( n = 6) and the closely related ST1633 ( n = 2). These sequence types have previously mainly been encountered in humans. The isolates of the second-largest cluster belong to ST5477 ( n = 5),so far exclusively isolated from cows in Rwanda. The third cluster consists of isolates of ST97 ( n = 4), which is a well-known bovine-adapted sequence type. These three clusters were all widespread over the country. Isolates of the usually human-adapted sequence types 1 ( n = 2) and 5 ( n = 1) were found and a single isolate of ST2430, previously found among humans in Africa. Finally, four isolates of novel sequence types were found: ST7108 ( n = 2), ST7109 ( n = 1), and ST7110 ( n = 1). The blaZ penicillin resistance gene was found in 84% of the isolates and was in all cases corroborated by phenotypic resistance determination. Five (20%) of the isolates carried a tetracycline resistance gene, tet(K) or tetM, and three of these five also displayed phenotypic resistance while two isolates carried a tetM-gene but were yet tetracycline susceptible. Seven (28%) isolates carried the dfrG gene conferring resistance to trimethoprim. Four of these isolates indeed were resistant to trimethoprim while three isolates were sensitive. The str gene conferring resistance to aminoglycosides was found in three isolates; however, none of these displayed resistance to gentamycin. Our data revealed a high diversity of the sequence types of S. aureus isolates from cows with subclinical mastitis in Rwanda. Two major clusters of ST97 and ST5477 are likely to be bovine adapted and cause mastitis while the third cluster of ST152 usually have been found in humans and may signify a recent transmission of these types from human to cows, for example from hand milking. The high prevalence of this sequence type among dairy cows may pose zoonotic threat. The sequence types were widely distributed without any geographic correlation. Penicillin resistance, the most common type of resistance with a prevalence over 80%, but also tetracycline and trimethoprim resistance were displayed by several isolates., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ndahetuye, Leijon, Båge, Artursson and Persson.)

The aim of this study was to generate knowledge on the most important milk quality and safety attributes, including somatic cell count (SCC), total bacterial count (TBC), Escherichia coli, Salmonella, and Brucella spp. antibodies and antibiotic residues in milk in the chain from farm to milk collection center (MCC) in Rwanda. In addition, we investigated farm and management factors associated with high TBC, SCC, and Salmonella counts. Raw milk was sampled at the farm and MCC levels. Milk samples were taken from dairy farms linked to 2 selected MCC in each of the 4 provinces in Rwanda. In total, 406 bulk milk samples from 406 farms and 32 bulk milk samples from 8 MCC were collected and analyzed. Farm milk average SCC varied between 180 × 10 3 and 920 × 10 3 cells/mL, whereas average SCC in milk samples at MCC varied between 170 × 10 3 and 1,700 × 10 3 cells/mL. The mean milk TBC of different farms per MCC varied between 1.1 × 10 6 and 1.6 × 10 7 cfu/mL, whereas in milk samples from different MCC, the mean TBC ranged between 5.3 × 10 5 and 2.4 × 10 8 cfu/mL. The high TBC in milk from MCC suggests proliferation or recontamination of milk by bacteria during transportation. Escherichia coli was detected in 35 of 385 farm milk samples and ranged between 5 cfu/mL and 1.1 × 10 4 cfu/mL, whereas in milk samples from the MCC, it was detected in 20 out 32 samples varying between 5 cfu/mL and 2.9 × 10 3 cfu/mL. Overall farm prevalence of Salmonella in milk samples was 14%, but no milk samples from MCC were positive for Salmonella. Five out of 22 bulk milk samples from different MCC were positive for Brucella spp. antibodies, but no Brucella antibodies were detected in milk samples from farms. The prevalence of antibiotic residues as detected by the Delvotest SP NT (DSM, Delft, the Netherlands) was low: 1.3% in farm milk samples and undetected in MCC milk samples. Lack of a separate milking area was associated with high TBC, whereas offering of supplemental feeds, keeping data of past diseases, and an unhygienic milking area were associated with high SCC. Lack of teat washing before milking was the only factor associated with Salmonella contamination of milk at the farm level. This study indicated high TBC and SCC of milk samples at the farm and MCC levels, which indicates both microbial contamination of milk and poor udder health in dairy cows. Presence of E. coli, Salmonella, and Brucella antibodies in milk was common, but finding antibiotic residues in milk was uncommon., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).)

A lack of knowledge of naturally occurring pathogens is limiting our ability to use the Antarctic to study the impact human-mediated introduction of infectious microorganisms have on this relatively uncontaminated environment. As no large-scale coordinated effort to remedy this lack of knowledge has taken place, we rely on smaller targeted efforts to both study present microorganisms and monitor the environment for introductions. In one such effort, we isolated Campylobacter species from fecal samples collected from wild birds in the Antarctic Peninsula and the sub-Antarctic island of South Georgia. Indeed, in South Georgia, we found Campylobacter lari and the closely related Campylobacter peloridis, but also distantly related human-associated multilocus sequence types of Campylobacter jejuni. In contrast, in the Antarctic Peninsula, we found C. lari and two closely related species, Campylobacter subantarcticus and Campylobacter volucris, but no signs of human introduction. In fact, our finding of human-associated sequence types of C. jejuni in South Georgia, but not in the Antarctic Peninsula, suggests that efforts to limit the spread of infectious microorganisms to the Antarctic have so far been successful in preventing the introduction of C. jejuni. However, we do not know how it came to South Georgia and whether the same mode of introduction could spread it from there to the Antarctic Peninsula., Competing Interests: I have read the journal’s policy and the authors of this manuscript have the following competing interests: Jonas Waldenström currently serves as an academic editor for PLOS ONE. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Raw milk may be a risk for public health if it is contaminated with zoonotic pathogens. To study the prevalence in unpasteurized milk from Swedish farms, bovine and small ruminant dairy farms were sampled. Since the sampling method and transport conditions may influence the outcome of analyses, efforts were made to optimize the methodology. Culturing of bacteria was done from in-line milk filters collected from the milk pipe at the point where it enters the milk bulk tank at the farms and this way of sampling was compared to sampling bulk tank milk (BTM) directly. Analysing milk filters were found to be superior to analysing BTM directly. Conditions for transport of milk filter samples were further improved by the addition of Cary Blair transport medium, which significantly increased the number of positive samples for pathogenic bacteria. The isolation of several foodborne pathogens from milk filters was demonstrated. The prevalence of samples with Staphylococcus aureus was 71% and 64%, and Listeria spp. 21% and 29% from dairy cow and goat/sheep farms, respectively. Campylobacter jejuni, Yersinia enterocolitica and verotoxigenic Escherichia coli (VTEC) O157 were detected in 9%, 2% and 2% of samples from bovine milk, respectively. We conclude that the choice of sampling method and sample handling influence the results of bacterial culturing. From the results of this study, we strongly recommend to sample in-line milk filters instead of BTM directly and to use Cary Blair medium during transport, especially if the samples are to be analysed for Campylobacter spp. and/or Listeria spp. The findings also show that unpasteurized milk from Swedish farms occasionally contain bacteria with zoonotic potential., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Extended-spectrum-cephalosporin-resistant Enterobacteriaceae are a public health concern due to limited treatment options. Here, we report on the occurrence and the molecular characteristics of extended-spectrum-cephalosporin-resistant Enterobacteriaceae recovered from wild birds (kelp gulls). Our results revealed kelp gulls as a reservoir of various extended-spectrum cephalosporinase genes associated with different genetic platforms. In addition, we report for the first time the presence of a known epidemic clone of Salmonella enterica serotype Heidelberg (JF6X01.0326/XbaI.1966) among wild birds., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

Reducing the prevalence of mastitis caused by Staphylococcus aureus (S. aureus) is essential to improve animal health and reduce economic losses for farmers. The clinical outcome of acute mastitis and risk of progression to persistent mastitis can, at least to some extent, be related to genetic variants of the strain causing the infection. In the present study we have used microarrays to investigate the presence of virulence genes in S. aureus isolates from dairy cows with acute clinical mastitis (n=70) and correlated the findings to other genotypic and phenotypic characteristics. Among the most commonly found virulence factors were genes encoding several hemolysin types, leukocidins D and lukM/lukF-P83, clumping factors A and B, fibrinogen binding protein and fibronectin-binding protein A. Some virulence factors e.g. fibronectin-binding protein B and Staphylococcus aureus surface protein G were less common. Genes coding for several staphylococcal enterotoxins and toxic shock syndrome toxin-1 (TSST-1) were commonly found, especially in one major pulsotype. No beta-lactamase genes were found in any common pulsotype, while present in some rare pulsotypes, indicated to be of human origin. Production of TSST-1, enterotoxins, hemolysins and beta-lactamase could all be positively correlated to presence of the corresponding genes. This study reveals a number of genotypic differences and similarities among common and rare pulsotypes of S. aureus from cases of mastitis in Sweden. The results could help the design of diagnostic tools to guide on-farm interventions according to the expected impact on udder health from a specific S. aureus genotype., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Mastitis is a serious medical condition of dairy cattle. Here, we evaluated whether the degree of virulence of mastitis pathogens in a mouse model can be linked to the inflammatory response that they provoke. Clinical isolates of Staphylococcus aureus ( S. aureus ) (strain 556 and 392) and Escherichia coli ( E. coli ) (676 and 127), and laboratory control strains [8325-4 ( S. aureus ) and MG1655 ( E. coli )], were injected i.p. into mice, followed by the assessment of clinical scores and inflammatory parameters. As judged by clinical scoring, E. coli 127 exhibited the largest degree of virulence among the strains. All bacterial strains induced neutrophil recruitment. However, whereas E. coli 127 induced high peritoneal levels of CXCL1, G-CSF, and CCL2, strikingly lower levels of these were induced by the less virulent bacterial strains. High concentrations of these compounds were also seen in blood samples taken from animals infected with E. coli 127, suggesting systemic inflammation. Moreover, the levels of CXCL1 and G-CSF, both in the peritoneal fluid and in plasma, correlated with clinical score. Together, these findings suggest that highly virulent clinical mastitis isolates produce a distinct cytokine profile that shows a close correlation with the severity of the bacterial infection.

Inflammation in the mammary gland (mastitis) is the most common disease in dairy herds worldwide, often caused by the pathogens Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Little is known about the effects of mastitis on drug transporters and the impact on transporter-mediated excretion of drugs into milk. We used murine mammary epithelial HC11 cells, after lactogenic differentiation into a secreting phenotype, and studied gene expressions of ABC- and SLC- transporters after treatment of cells with S. aureus and lipopolysaccharide, an endotoxin secreted by E. coli. The studied transporters were Bcrp, Mdr1, Mrp1, Oatp1a5, Octn1 and Oct1. In addition, Csn2, the gene encoding β-casein, was analyzed. As biomarkers of the inflammatory response, gene expressions of the cytokines Il6 and Tnfα and the chemokine Cxcl2 were determined. Our results show that S. aureus and LPS treatment of cells, at non-cytotoxic concentrations, induced an up-regulation of Mdr1 and of the inflammatory biomarkers, except that Tnfα was not affected by lipopolysaccharide. By simple regression analysis we could demonstrate statistically significant positive correlations between each of the transporters with each of the inflammatory biomarkers in cells treated with S. aureus. The coefficients of determination (R2) were 0.7-0.9 for all but one correlation. After treatment of cells with lipopolysaccharide, statistically significant correlations were only found between Mdr1 and the two parameters Cxcl2 and Il6. The expression of Csn2 was up-regulated in cells treated with S. aureus, indicating that the secretory function of the cells was not impaired. The strong correlation in gene expressions between transporters and inflammatory biomarkers may suggest a co-regulation and that the transporters have a role in the transport of cytokines and chemokines. Our results demonstrate that transporters in mammary cells can be affected by infection, which may have an impact on transport of essential compounds and contaminants into milk., Competing Interests: The authors have declared that no competing interests exist.

Background: Anaplasma phagocytophilum (formerly Ehrlichia phagocytophila) is an obligate intracellular bacterium causing the disease tick-borne fever (TBF) in domestic ruminants. An effective vaccine against the infection has been demanded for livestock by sheep farmers and veterinary practitioners for years., Findings: In the present study, we immunized lambs with an inactivated suspension of 1 × 10(8) killed A. phagocytophilum organisms mixed with adjuvant (Montanide ISA 61VG; Seppic). Twelve 9-months-old lambs of the Norwegian White Sheep breed were used. A full two-dose series of immunization was given subcutaneously to six lambs with a 4 week interval between injections. One month after the last immunization, all lambs were challenged with the homologous viable variant of A. phagocytophilum. After challenge, all lambs showed clinical responses for several days, although the immunized lambs reacted with an anamnestic response, i.e. significant reduction in infection rate and a significantly higher antibody titer., Conclusion: Immunization with inactivated A. phagocytophilum did not protect lambs TBF.

In a herd of 20 sheep in Sweden, a country where brucellosis has never been diagnosed in sheep or goats, a total of six sheep were found serologically positive to Brucella melitensis in two different rounds of sampling. Yersinia enterocolitica serotype O:9 could at the time of the second sampling be isolated from four sheep, one of them at the same time serologically positive for B. melitensis. The article describes the case and gives some background information on brucellosis and Y. enterocolitica in general as well as a more specific description of the Swedish surveillance program for B. melitensis and the test procedures used. The problem with false-positive reactions, in particular its implications for surveillance programs in low prevalence or officially brucellosis-free countries, is discussed.

Background: Dairy cattle were used as sentinels for the presence of Leptospira infection in Swedish livestock in four regions contrasting in precipitation and temperature during the summer time. The aim of the study was to estimate the prevalence of five serovars of Leptospira of low pathogenicity in dairy cattle in these four regions., Findings: Around 150 blood samples were collected from five dairy farms from each region, making 610 samples in total, during December 2009. The samples were screened for L. kirschneri sv Grippotyphosa, L. interrogans sv Icterohaemorrhagiae, L. interrogans sv Canicola, L. borgpetersenii sv Sejroe and one domestic strain similar to sv Sejroe, called strain Mouse 2A using the Microscopic Agglutination Test. Six animals (1%) were seropositive for the strain Mouse 2A. Four of the positive samples were from the south-west region which also was the region with highest precipitation. There were no positive samples to any of the other serovars studied., Conclusions: The present data indicate that there is a low seroprevalence of Leptospira in Swedish dairy cows. These findings can be used as baseline data to investigate the effects of, for instance, climatic change or alterations in wildlife reservoir populations on the seroprevalence of Leptospira in the future.

The main aim of this study was to examine genotypic diversity of 82 Staphylococcus aureus isolates from cases of acute clinical mastitis in cattle using pulsed-field gel electrophoresis, and to investigate pulsotype differences between geographical regions of Sweden. The work also investigated haemolysis type (alpha, alphabeta), beta-lactamase production, and the association between S. aureus pulsotypes and breed, parity and presence of teat lesions. All isolates came from different farms. In total, 25 pulsotypes were found, but most only once or twice. The most common pulsotype accounted for 26% of the isolates and was found in all regions. The distribution of pulsotypes in the southern region of the country differed from the northern and middle regions. Alphabeta- or alpha-haemolysis was found in 66% and 34% of the isolates, respectively, and beta-lactamase production was found in 9% of the isolates. Variation in haemolysis type or beta-lactamase production was found within some pulsotypes. The results indicate that some pulsotypes have spread widely between herds within the country., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

To investigate occurrence of acquired antimicrobial resistance in udder pathogens MICs in Staphylococcus aureus (n=211), coagulase-negative staphylococci (CNS) (n=56), Streptococcus uberis (n=113), Streptococcus dysgalactiae (n=152), Streptococcus agalactiae (n=6), Escherichia coli (n=163), and Klebsiella spp. (n=42) were determined using microdilution. Isolates were from a nation wide survey employing strict inclusion criteria. Presence of acquired resistance was evaluated by species-specific epidemiological cut-off values issued by EUCAST. Penicillin or methicillin resistance in staphylococci were however evaluated by beta-lactamase production or presence of the mecA gene, respectively. Staphylococci were mostly susceptible to antimicrobials tested but 7.1% of S. aureus and 12.5% of CNS were resistant to penicillin by beta-lactamase production. Methicillin resistance was not found in S. aureus. All Streptococcus dysgalactiae and S. agalactiae were susceptible to penicillin. Bimodal MIC distributions for tetracycline in S dysgalactiae and S. uberis indicate acquired resistance in some isolates. Among E. coli 12.3% of isolates were resistant to one or more antimicrobials. Resistance to streptomycin (11.0%), sulphametoxazole (8.6%), ampicillin (7.4%), or tetracycline (4.9%) were the most common traits. Klebsiella spp. were resistant to ampicillin and some isolates also to tetracycline (7.1%) or sulphonamide (9.5%). The study shows that in Sweden bacteria associated with acute clinical mastitis for the most part are susceptible to antimicrobials used in therapy but resistance to penicillin in S. aureus is not uncommon. Penicillin is recommended for treatment of mastitis caused by gram-positive pathogens and regular monitoring of beta-lactamase production in S. aureus is therefore recommended in herds with udder health problems.

Twenty-one lambs were used to investigate whether their response to an infection with Ehrlichia phagocytophila was dose-dependent Four groups of four lambs were infected intravenously with a dilution in physiological saline of E phagocytophila-infected sheep blood containing either 1.3 x 10(5) infected cells, or approximately 43 infected cells, 4.3 infected cells, or 1.3 infected cells (mean values) and four lambs were left uninfected. The incubation period was significantly shorter in the lambs infected with the highest dose of E phagocytophila. However, the clinical and haematological changes observed, and the weekly weight gains of the lambs were independent of the dose of E phagocytophila. As little as one Ephagocytophila infected cell may be enough to transmit the infection.

For diagnosis of equine granulocytic ehrlichiosis (EGE) serological testing of antibodies to Ehrlichia equi is frequently used. An elevated antibody level is often misinterpreted as confirmative of active infection and results in treatment with antibiotics. If only seropositivity is considered as the diagnostic criterium, many horses showing convalescence titres will be treated. This study was undertaken to obtain information about the kinetics of antibodies during the course of infection and, for this purpose, 45 horses with clinical signs of EGE and confirmed ehrlichiaemia were monitored serologically and clinically over time. For a correct handling of cases with suspected EGE, the following results should be helpful: (i) 44% of the horses in the acute ehrlichiaemic stage were found to be serologically positive to E. equi; (ii) all horses showed a rapid increase in antibody titre, reaching maximum value within a month after the ehrlichiaemic stage; (iii) when 8 months had passed, titres had decreased, but 18 of 24 examined horses were still serologically positive; (iv) after 12-15 months most of the horses (n = 10) were serologically negative; and (v) the period required for complete clinical recovery varied from one day up to 6 months after antibiotic treatment.

Granulocytic ehrlichiosis is attracting increasing attention as a disease of both humans and animals. Pasture fever in cattle is a form long known in Sweden, and a similar disease was observed in Swedish dogs and horses in the late 1980s. The first cases of human granulocytic ehrlichiosis (HGE) reported from the USA in 1994 proved to have been caused by a species of Erhlichia identical or very similar to the species found in Swedish dogs and horses. Presence of the HGE agent has now been demonstrated in Ixodes ricinus ticks in Sweden. Serological studies among residents in areas of Sweden with a high incidence of ticks have shown the presence of antibodies against the HGE agent in over 10 per cent of cases. To date, there have been about 10 documented cases of HGE in Sweden, a figure to be compared with those for dogs and horses among which ehrlichiosis is relatively common.

Pigs in three specialized fattening herds were studied with respect to some immune functions, viral infections revealed by presence of interferon-alpha in serum as well as bacterial infections indicated by antibodies to Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae. Pigs from different breeders had signs of varying but low incidence of such infections. After transport to the fattening herds, viral infections were activated and spread during the first month, and a maximum of 19% of the pigs had signs of ongoing infections at one week. At this time, blood leukocytes prepared from the pigs had diminished ability to produce interferon-alpha in vitro. Except during the first month, serological evidence of Mycoplasma hyopneumoniae infections became gradually more frequent, and 91% of the pigs were seropositive at slaughter. Early, but not late, infections appeared to inhibit growth of the pigs as indicated by time for slaughter, but only late infections may be registered as pneumonia at slaughter. The prevalence of pigs with serological evidence of Actinobacillus pleuropneumoniae infections increased late in the fattening period, but such infections had no demonstrable impact on the time for slaughter.

A gene encoding the porcine interferon-beta (poIFN-beta) was cloned from a genomic library. The sequence of a potential intronless coding region as well as 1,265 bp of the 5'- and 277 bp of the 3'-flanking regions is presented. The gene is predicted to encode a mature protein of 165 amino acids and a signal peptide of 21 amino acids. This probable poIFN-beta shows high homology (63%) with human (hu) IFN-beta at the amino acid level, but less with porcine (po) IFN-alpha 1 (32%). It contains three cysteines and three potential N-glycosylation sites. A region of the 5' flank (-116 to -159) of the gene is homologous to the IFN gene regulatory element (IRE) of the huIFN-beta gene which mediates virus inducibility. Southern blot analysis indicates that the poIFN-beta gene is present as a single copy in the porcine genome. Its expression in porcine peripheral blood leukocytes stimulated in vitro by pseudorabies virus (PRV) was demonstrated at the RNA level both by Northern blot analysis and by in situ hybridization. The latter approach in addition detected only about one IFN-beta mRNA-containing cell per 2,000 PRV-stimulated porcine leukocytes, a frequency in the same range as that for leukocytes containing IFN-alpha mRNA.

Two murine monoclonal antibodies (mAbs) directed against different epitopes on recombinant porcine interferon-alpha (IFN-alpha) were selected and used to construct a two-site ELISA. This ELISA, when performed in a one-step version, detected about 0.5 units ml-1 of IFN-alpha and showed similar sensitivity but better precision than a cytopathic effect inhibition bioassay. Estimates of IFN-alpha in tissue culture medium by the two assays correlated well. In contrast, one or several factors in porcine serum reduced the sensitivity of the ELISA. Measurements of IFN-alpha in porcine serum was, however, possible in a two-step version of the ELISA, with a sensitivity of about 1 unit IFN-alpha ml-1. Results of ELISA and bioassay agreed, except that the ELISA possibly produced false positive results in two out of a total of 91 sera negative in the bioassay. In addition, one of 23 sera positive in the bioassay was negative in the ELISA.

Pigs were transported from several breeding facilities at the age of 10-12 weeks and regrouped in a fattening farm, specialized in breeding pigs for subsequent slaughter. Blood samples were obtained from the animals just before transport and daily for 17 days after installation in the fattening farm. On each occasion a group of ten animals (170 animals in total) was sampled. The levels of interferon-alpha (IFN-alpha) in serum were measured as antiviral activity in a cytopathic effect inhibition assay. Beginning at day 4 after installation, a significant proportion of sera contained IFN-alpha, with the highest incidence of IFN-alpha positive animals (25%) and IFN-alpha titers on days 5-10. This indicates a high frequency of viral infections in the animals. The in vitro ability of peripheral blood mononuclear leukocytes (PBMCs) to produce IFN-alpha after stimulation by glutaraldehyde-fixed pseudorabies virus-infected PK15 cells and their proliferative response to the T-cell mitogen leukoagglutinin (LA) was also monitored. There was a significant, but moderate decrease in the ability of PBMCs to produce IFN-alpha during the observation period. In contrast, the response to the mitogen LA decreased markedly during the first 5 days, and thereafter remained at the same low level. The proliferative response to LA was significantly lower for PBMCs from serum of IFN-alpha-positive than from IFN-alpha-negative animals. These impaired PBMC responses could indicate a stress-induced immune depression, possibly contributing to the high incidence of viral infections.