Search

Newly emerged influenza A(H1N1) pdm09 virus infection in Norwegian pigs, although often observed in a subclinical form, can lower the pig's growth performance by reducing feed efficiency in terms of a poorer feed conversion ratio. Infected pigs would consume more feed and require protracted production time to reach market weight. In our observational longitudinal study, growth performance data from 728 control pigs and 193 infected pigs with known viral shedding time points were analyzed using mixed linear regression models to give estimates of the marginal effects of infection. Gaussian curves describing the variability of the estimates at the individual pig level formed the fundamental inputs to our stochastic models. The models were constructed to simulate the summed negative effects of the infection at the batch level of 150 fattening pigs growing from 33 to 100 kg. Other inputs of variability and uncertainty were 1) batch transmission points, 2) pig infection points to reflect the disease transmission dynamics of the virus, and 3) final prevalence of infected pigs in the batch. Monte Carlo random sampling gave 5,000 estimates on the outputs of the marginal effects for each pig. These results were summed up to provide estimates for a batch size of 150 pigs. This figure was adjusted by our final prevalence distribution function, which was also derived from the longitudinal study with 12 cohorts of infected pigs. For a 150-fattening-pig herd randomly selected from the population, the marginal effects of the infection were 1) 835 kg (fifth percentile) to 1,350 kg (95th percentile) increased feed intake and 2) 194 (fifth percentile) to 334 (95th percentile) pig days in excess of expected figures for an uninfected batch. A batch infected during growth phase 3 (81 to 100 kg BW) gave the worst results since the longitudinal study showed that a pig infected during growth phase 3 required more feed and a greater protracted production time compared to younger infected pigs. Sensitivity analysis showed that final prevalence had the greatest impact on the conditional mean and variation of the marginal effects of infections. Batch transmission point was the next most influential factor. Lowering the final prevalence and preventing older fattening pigs from being infected will have the greatest benefit in saving feed cost and reducing delay in getting the pigs to the market. [ABSTRACT FROM AUTHOR]

This is the first comprehensive study on the occurrence and distribution of piscine reovirus ( PRV) in Atlantic salmon, Salmo salar L., caught in Norwegian rivers. PRV is a newly discovered reovirus associated with heart and skeletal muscle inflammation ( HSMI), a serious and commercially important disease affecting farmed Atlantic salmon in Norway. A cross-sectional survey based on real-time RT- PCR screening of head kidney samples from wild, cultivated and escaped farmed Atlantic salmon caught from 2007 to 2009 in Norwegian rivers has been conducted. In addition, anadromous trout (sea-trout), Salmo trutta L., caught from 2007 to 2010, and anadromous Arctic char, Salvelinus alpinus (L.), caught from 2007 to 2009, were tested. PRV was detected in Atlantic salmon from all counties included in the study and in 31 of 36 examined rivers. PRV was also detected in sea-trout but not in anadromous Arctic char. In this study, the mean proportion of PRV positives was 13.4% in wild Atlantic salmon, 24.0% in salmon released for stock enhancement purposes and 55.2% in escaped farmed salmon. Histopathological examination of hearts from 21 PRV-positive wild and one cultivated salmon (Ct values ranging from 17.0 to 39.8) revealed no HSMI-related lesions. Thus, it seems that PRV is widespread in Atlantic salmon returning to Norwegian rivers, and that the virus can be present in high titres without causing lesions traditionally associated with HSMI. [ABSTRACT FROM AUTHOR]

Aims: To characterize a number of Shiga toxin-producing Escherichia coli (STEC) isolates from sheep and to discuss the potential of these isolates as human pathogens. Methods and Results: Twelve different O-groups and seven different H-types were identified by standard serotyping methods. The most common serotypes were O5:NM, O6:H10, O91:NM and O128:NM. Polymerase chain reaction (PCR) was used for the detection of virulence factor genes. Of 102 isolates, 86·3% carried stx 1 and 83% of these were also positive in the stx 1OX3 -specific PCR. stx 2 was carried by 55·9% of the isolates and 77·2% of these were also positive in the stx 2d -specific PCR. The Vero cell assay showed high toxin production in 70·6% of the isolates. None of the isolates carried eae . Conclusions: The study supports the animal–host relationship suggested in other studies with STEC serogroups O5, O91 and O128 strongly associated with sheep. Most sheep STEC carry stx 1OX3 (except O91) and the dominating stx 2 variant is stx 2d . One stx profile clearly dominates within a serotype. Significance and Impact of the Study: In spite of the predominance of certain sheep-associated STEC, sheep cannot be excluded as carriers of human pathogenic STEC. [ABSTRACT FROM AUTHOR]

We studied the prevalence of Salmonella enterica subspecies diarizonae serovar 61:k:1,5,(7) (S. IIIb 61:k:1,5,(7)) in 133 Norwegian sheep herds from throughout the country. We used a nested case-control study to identify major risk factors. Two pooled samples (one from lambs and one from adult sheep) were collected from each herd from (10 different) abattoirs. The regional prevalence varied from 0 to 45%, and was more prevalent in adults than in lambs. Sixteen of the 133 herds tested positive to S. IIIb 61:k:1,5,(7), and these positive herds were included in the questionnaire-based nested case-control part of the study. The controls were stratified according to abattoir. Above-median herd size, having white crossbreed sheep, and higher annual replacement percentage were the most evident risk factors. [Copyright &y& Elsevier]

Abstract: In the present study, polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were determined in 423 breast milk samples from women living in Norway. Various predictors for the contaminant levels were also investigated. The samples were collected in six counties, representing South, Central and North Norway in 2002–2006. Initial results showed significantly lower levels of OCPs in breast milk from ethnic Norwegians (N =377) compared to ethnic non-Norwegians (N =46). Median concentrations (range) of PCBs, p,p′-DDE, HCB, β-HCH and oxychlordane in breast milk of the Norwegian women, all parities included, were 103 (34–450), 41 (5.4–492), 11 (3.6–24), 4.7 (0.9–37) and 2.8 (0.5–16) ng/g lipid weight, respectively. Results indicated that sum of 18 PCBs, p,p′-DDE and β-HCH are good predictors for monitoring of PCB, DDT and HCH levels in Norwegian breast milk. Multivariable linear regression analyses showed that age was strongly associated with increasing OC levels (P <0.001), whereas parity was associated with decreasing OC levels (P <0.001). Smoking was associated with higher levels of PCBs, p,p′-DDE and β-HCH. The models explained from 17 to 35% of the variance. Median levels of OCs in the present Norwegian primparaes seemed to be 29–62% lower than corresponding results found in a Norwegian study from 2000–2002. [Copyright &y& Elsevier]

Background: Preventing pathogens from entering the broiler premises is the main biosecurity measure at farm level. In conventional broiler production, chickens are kept indoors during the entire production period. Pathogens can enter the broiler-producing unit from sources such as water, equipment, personnel, insects, and rodents. The possible routes must be controlled, and corrective measures applied when necessary. The objective of this study was to (1) develop a hygiene protocol and test the scheme on 30 farms, and (2) compare the results to their Campylobacter-colonised status. A Hygiene Performance Rating protocol at farm level (HPR-F) was developed to systematically review the production to identify risk areas to biosecurity. The HPR-F consists of 13 categories with related questions. For each question, a score was given from 1 to 3, where 1 meant "acceptable", 2 was "potential for improvements", and 3 was "not acceptable". Scores for each question were multiplied with weight factors for hygienic impact and economic consequences describing whether the necessary improvement depends on a significant investment or is a cheap quick-fix and calculated into a percentage where 100% is perfect hygiene. The 30 farms in the study were selected from one county in Norway. The Campylobacter-results for each of the 30 farms in 2019-2021 were given according to rules in the Norwegian Action Plan against Campylobacter faecal sampling on-farm 3-6 days prior to slaughter., Results: The overall results from the HPR-F showed that the general hygiene level was high in all farms. The mean total hygiene score was 82% and varied from 70 to 92%. The category Handling dead chicken had the highest hygiene score (93%), and Ventilation had the lowest score (55%). The HPR-F results were compared to the Campylobacter-status for the 30 farms: Campylobacter-negative flocks had slightly higher total scores than Campylobacter-positive flocks (P = 0.19). Among others, the category Outdoor area (vegetation close to the premises' walls) was identified as the most stable factor in relation to be colonised with Campylobacter., Conclusions: The HPR-F tested in this research trial provides a tool for veterinarians, advisors, and poultry farmers to improve biosecurity at farm level and enhance the preventive animal health initiatives., (© 2024. The Author(s).)

Background: Specific studies on the epidemiology of necrotic enteritis in turkeys are absent in the literature. Necrotic enteritis is common in turkeys and a leading cause of use of therapeutic antibiotics. This study describes the incidence of necrotic enteritis in turkey farms, and the association between incidence and bird age, season, faecal oocyst counts, grow-out size and feed mill., Results: Necrotic enteritis was diagnosed post mortem in 20.2 % of 545 grow-outs of commercial female and male B.U.T. 10 turkeys started during the years 2010-2016. 80 % of all cases occurred at four to seven weeks of age. Median (minimum-maximum) age at disease detection was 37 (18-115) days. Turkey age at detection was influenced by season, and varied from 33 days among grow-outs hatched in February to 42 days among those hatched in July-August. The incidence also varied with season, showing peak occurrence among grow-outs hatched during February-March and the lowest incidence in turkeys hatched in July-August. 59 % of all cases were detected in 25 % of the farms. The incidence per farm varied from below 4 to 59 %. A multilevel mixed-effects logistic regression model indicated clear impacts of farm and season on incidence, and border-line impacts of grow-out size and feed mill. Grow-outs diagnosed with necrotic enteritis had higher counts of faecal Eimeria oocysts than grow-outs without a diagnosis. This difference was particularly clear during the high-risk period at five to seven weeks of age. Necrotic enteritis was the cause of treatment with therapeutic antibiotics in 88.2 % of all cases of treatment., Conclusions: Our data indicate that necrotic enteritis incidence in turkeys can be substantially influenced by risk factors at farm level. The incidence showed two seasonal peaks; a moderate peak in turkeys hatched in October/November and a marked peak in turkeys hatched during February/March. Mitigation measures at the farm may therefore be of particular importance during these months in farms located in the Northern temperate zone. Measures which effectively reduce counts of faecal Eimeria oocyst are likely to be among the more promising actions to take both at the farm and at population level., (© 2021. The Author(s).)

Our aim was to investigate the associations between management factors, compliance with current legislation, and herd-level calf mortality. In a national calf welfare audit, veterinary inspectors from the Norwegian Food Safety Authority assessed compliance with current legislation on calf welfare (n = 912 herds). Nine criteria were assessed and rated as satisfactory (1) or not satisfactory (0): housing, natural behavior, single pens, colostrum feeding, feeding, water, surveillance, illness/injuries, and <5% mortality rate. In addition, a short questionnaire on milk feeding management for 3-wk-old calves was distributed to all national calf welfare audit herds, and data on mortality and disease recordings were obtained from the Norwegian Dairy Herd Recording System (NDHRS). A herd welfare compliance score (WCS) for each farm was constructed, summarizing the results for the individual criteria. Most herds had a high WCS (median 9.0, range 2-9). Fifty-six percent of the national calf welfare audit herds (508/912) responded to the questionnaire. We performed a cross-sectional study using a data set from 431 herds with available data on recorded disease and mortality events from the NDHRS, recordings from the national calf welfare audit, and the questionnaire. A mixed-effects negative binomial model with Norwegian Food Safety Authority district as the random effect was fitted to the data. Of the 416 herds with available data on calf mortality, 108 (25.9%) reported no mortality in 2016, and the median 6-mo mortality rate was 0.064 (interquartile range 0-0.11) dead calves per 6 calf-months at risk, based on NDHRS recordings. Calf mortality rates were higher in herds whose calves did not have free access to water (incidence rate ratio 1.29; 95% confidence interval 1.02-1.64) and higher in herds that had reported calf disease events (incidence rate ratio 1.31; 95% confidence interval 1.09-1.54). Neither the WCS nor any of the calf milk feeding management factors were associated with mortality, but more than half of producers (59.6%) fed less milk than currently recommended for 3-wk-old calves (8 L/d first 3 to 4 wk). These results indicate that a lack of access to water was associated with higher calf mortality rates. Herds with registered calf disease events had a higher incidence rate ratio of mortality. This finding may be linked to suboptimal calf management, leading to more calf diseases and mortality; or it may be that veterinary consultancy occurs too late or only for the worst cases. There is room for improvement in Norwegian dairy calf management, and water should be provided to young calves., (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/).)

Objective: To analyse the effect of treatment method and other risk factors on survival in dogs with cranial cruciate ligament disease (CCLD)., Methods: A historical cohort study of 333 dogs presenting with CCLD at two University Hospitals (2011-2016) was performed. Signalment, history, treatment and follow-up details were retrieved from medical records, dog owners and referring veterinarians. Treatment groups were defined; conservative or surgical with either lateral fabellotibial suture (LFS) or osteotomy procedures. Multivariable Cox proportional hazards models were applied to evaluate risk factors for disease-related and overall survival., Results: Sixty-five dogs were conservatively managed, 125 treated with LFS and 143 with osteotomy techniques. At follow-up (autumn 2018), 164 dogs (49.3 %) were alive and 169 (50.7 %) were dead. Both final Cox proportional hazards models included variables for treatment, age, weight and hospital. In addition, the final disease-related model included a variable for orthopaedic comorbidity, while non-orthopaedic comorbidities and a time-varying effect for age on a linear scale were included in the overall survival model. Treatment method was found to have an effect on both disease-related and overall survival and surgical treatment was associated with a lower hazard than conservative treatment., Conclusion: Survival in dogs with CCLD is influenced by treatment strategy, comorbidities, age and weight., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Members of the Pestivirus genus (family Flaviviridae ) cause severe and economically important diseases in livestock. Serological studies have revealed the presence of pestiviruses in different cervid species, including wild and semi-domesticated Eurasian tundra reindeer. In this retrospective study, serum samples collected between 2006 and 2008 from 3339 semi-domesticated Eurasian reindeer from Finnmark County, Norway, were tested for anti-pestivirus antibodies using an enzyme linked immunosorbent assay (ELISA) and a subset of these by virus neutralization test (VNT). A seroprevalence of 12.5% was found, varying from 0% to 45% among different herding districts, and 20% in western Finnmark, as compared to 1.7% in eastern Finnmark. Seroprevalence increased with age. Pestivirus-specific RNA was not detected in any of the 225 serum samples tested by real-time RT-PCR. Based on VNT results, using a panel of one bovine viral diarrhea virus (BVDV) strain and two border disease virus (BDV) strains, the virus is most likely a reindeer-specific pestivirus closely related to BDV. A characterization of the causative virus and its pathogenic impact on reindeer populations, as well as its potential to infect other domestic and wild ruminants, should be further investigated., Competing Interests: The authors declare no conflict of interest.

In poultry flocks, flock weight uniformity is often defined as the percent individuals within 10% of the mean body weight (BW) and the variability of this uniformity can be expressed as the CV of BW. Flock weight uniformity is a standardized and objective measured, and could potentially be used as a welfare indicator; however, little is known about the relationship between flock uniformity and other production measures on-farm or at slaughter. The aim of this study was to investigate the associations between carcass weight uniformity (CV of BW) and production measures on-farm and at slaughter in Norwegian commercial broiler flocks. A total of 45 randomly selected mixed-sex Ross 308 broiler flocks were visited prior to slaughter at 28 to 30 D of age (average slaughter age 30.6 D). All flocks were raised under similar farm management systems. The Welfare Quality protocol for broilers was used to assess different animal welfare indicators in each flock. All production data from the slaughterhouse were collected for each flock, including carcass weight uniformity (%), mortality (%), growth rate (g), feed conversion ratio (FCR), and rejected birds (%) in different rejection categories. Univariable and multivariable linear regression models were used to investigate the associations between flock weight uniformity and production and welfare measures. The results showed that flock uniformity varied from 11% to 18% between flocks within the same hybrid, similar management standards, and similar slaughter age (day 29 to 32). Poorer uniformity (i.e., high CV) was associated with increased first week mortality (P < 0.004, r = 1.48, increased total mortality (P < 0.013, r = 0.01), increased FCR (i.e., less efficient growth) (P < 0.024, r = 0.06), reduced growth rate (P < 0.0012, r = -0.01), and a reduced rejection rate at slaughter (P < 0.006, r = -0.01). The results show that flock uniformity varies across broiler flocks, and is associated with several production measures., (© The Author 2019. Published by Oxford University Press on behalf of Poultry Science Association.)

Background: A retrospective case-control study was conducted to estimate breed predisposition for common orthopaedic conditions in 12 popular dog breeds in Norway and Sweden. Orthopaedic conditions investigated were elbow dysplasia (ED); cranial cruciate ligament disease (CCLD); medial patellar luxation (MPL); and fractures of the radius and ulna. Dogs surgically treated for the conditions above at the Swedish and Norwegian University Animal Hospitals between the years 2011 and 2015 were compared with a geographically adjusted control group calculated from the national ID-registries. Logistic regression analyses (stratified for clinic and combined) were used to calculate odds ratios (OR) and 95% confidence intervals. Mixed breed dogs were used as reference., Results: Breeds found at-risk for ED were the Labrador retriever (OR = 5.73), the Rottweiler (OR = 5.63), the German shepherd dog (OR = 3.31) and the Staffordshire bull terrier (OR = 3.08). The Chihuahua was the only breed where an increased risk for MPL (OR = 2.80) was identified. While the Rottweiler was the only breed predisposed for CCLD (OR = 3.96), the results were conflicting for the Labrador retriever (OR = 0.44 in Sweden, 2.85 in Norway); the overall risk was identical to mixed-breed dogs., Conclusions: Most results are in concordance with earlier studies. However, an increased risk of CCLD was not identified for the Labrador retriever, the Staffordshire bull terrier was found to have an increased risk of ED and some country-specific differences were noted. These results highlight the importance of utilising large caseloads and appropriate control groups when breed susceptibility is reported.

Pancreas disease (PD) in marine salmon farming is caused by salmon pancreas disease virus (SPDV). Virus survival, infection pressure and contact networks among farms influence the potential of PD to spread. The present study aims to explore contact networks and infection pressure and their ability to explain transmission dynamics of PD in a Norwegian fjord. In this study, we included all records of PD by subtype 3 (SPDV3) in the study population from the first reported in August 2006 to the last reported in November 2009. Using logistic regression analyses, we found that contact network by water transport explained better transmission of PD than contact networks defined by ownership or close distance to infected farms. Hydrodynamic modelling can be a valuable tool to forecast the spread of PD and thereby take actions to reduce the transmission. Knowing the risk of getting infected, it is important to avoid water transport from infected farms when new cohorts are transferred to sea water, and to have conscious control regarding management operations between farms., (© 2013 John Wiley & Sons Ltd.)

Malignant catarrhal fever (MCF) is caused by a group of gammaherpesviruses that primarily affect domestic and wild ruminants. Using competitive-inhibition enzyme-linked immunosorbent assay, we screened 3,339 apparently healthy, semidomesticated reindeer (Rangifer tarandus tarandus) from Finnmark County, Norway, sampled during slaughter. The overall antibody prevalence was 3.5% and varied among reindeer herding districts in Finnmark (0-6.7%), the largest reindeer herding region in Norway. The risk of exposure to gammaherpesvirus (i.e., seroconversion) was significantly higher for adult reindeer than it was for calves ≤1 yr, for reindeer in east Finnmark (3.8%) compared with west Finnmark (3.3%), and with increasing population density. No evidence of disease associated with this virus was detected in reindeer sampled for this study, but because samples were collected at slaughterhouses, one cannot discard the possibility of these events happening in the field. The low antibody prevalence could indicate occasional infection of reindeer with another ruminant gammaherpesvirus or the presence of a yet-unknown, specific, low-pathogenic reindeer gammaherpesvirus. Further studies should aim at characterizing the virus circulating in reindeer and address the potential clinical impact of this virus.

Animal cleanliness in dairy herds is essential to ensure hygienic milk production, high microbial quality of carcasses, good hide quality, and animal welfare. The objective of this study was to identify on-farm factors associated with dairy cattle cleanliness. The study also examined differences in risk factors and preventive factors between contrasting herds regarding cattle cleanliness. In total, 60 dairy herds, selected from a national database, were visited by 2 trained assessors during the indoor feeding period in February and March 2009. In Norwegian abattoirs, cattle are assessed and categorized according to hide cleanliness, based on national guidelines, using a 3-category scale. Dirty animals result in deductions in payment to farmers. "Dirty" herds (n=30) were defined as those that had most deductions in payment registered due to dirty animals slaughtered in 2007 and 2008. "Clean" herds (n=30) were those that had similar farm characteristics, but slaughtered only clean animals during 2007 and 2008, and thus had no deductions in payments registered. The dairy farms were located in 4 different areas of Norway. Relevant information, such as housing, bedding, feeding, and management practices concerning cleaning animals and floors, was collected during farm visits. In addition, the cleanliness of each animal over 1 yr of age (4,991 animals) was assessed and scored on a 5-point scale, and later changed to a dichotomous variable during statistical analysis. Milk data (milk yield and somatic cell counts) were obtained from the Norwegian Dairy Herd Recording System. Factors associated with dirty animals in all 60 herds were, in ranked order, high air humidity, many dirty animals slaughtered during the previous 2 yr, lack of preslaughter management practices toward cleaning animals, animal type (heifers and bulls/steers), housing (freestalls and pens without bedding), manure consistency, and lack of efforts directed toward cleaning the animals throughout the year. Additional factors associated with dirty animals in the dirty herds were water leakage from drinking nipples/troughs into lying areas, bedding type, and feed type. In the clean herds, additional risk factors were water leakage from drinking nipples/troughs and low milk yield., (Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The meat industry in Norway has developed national guidelines for Good Hygiene Practices for slaughtering and skinning, based on categorisation of animals. These include shearing sheep and lambs in the abattoirs immediately before slaughter. The aim of this study was to investigate microbiological carcass contamination associated with: (i) different shearing regimes; (ii) fleece cleanliness; and (iii) the slaughter process. In addition, the efficacy of the national guidelines in reducing microbial contamination was evaluated. A total of 280 swab samples were collected from the brisket areas (100 cm(2)) of 140 naturally contaminated lamb carcasses in a commercial abattoir. Half the samples were collected at skinning of brisket areas at the start of the slaughter-line and half of them were collected at the end of slaughter-line, just before chilling. The lambs were divided into four groups (n=35) according to the duration of the period between shearing and slaughter: (i) 0 days (shorn at the abattoir immediately before slaughter); (ii) three days; (iii) seven days; and (iv) not shorn. Mean log colony forming units (CFU) per 100 cm(2) at skinning were 5.78 and 6.95 for aerobic plate count (APC) (P<0.05), 1.65 and 2.78 for Escherichia coli (P<0.05) for shorn and unshorn lambs, respectively. For shorn lambs, divided according to the period between shearing and slaughter, the mean log CFU per 100 cm(2) were 5.45, 5.75, 6.12 (APC) and 1.77, 1.46, 1.71 (E. coli) for the 0-days, 3-days and 7-days groups, respectively (P<0.05 for the difference between 0- and 7-days groups in APC results). A four-category scale (0-3) was used for assessing fleece cleanliness before skinning. Visually clean lambs (score '0') had lower levels of APC on the carcass surfaces than those categorised as dirty (score '2-3') (P<0.05). The carcasses at the end of the slaughter-line had lower levels of APC than they had at skinning. However, the statistical significant reduction of E. coli on carcass surfaces at skinning point for shorn lambs, were impaired and no longer significantly different from the unshorn group at the end of the slaughter-line. The increased E. coli level at the end of the slaughter-line might be explained by weaknesses related to slaughter hygiene in particular suboptimal evisceration in the abattoir which was used as a basis for our trial, and thus the national guidelines concerning shearing had not the fully intended effect on reducing microbial carcass contamination., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Abattoirs have to enumerate Escherichia coli on carcass surfaces as part of compulsory HACCP monitoring and they therefore need rapid and reliable methods. The objective of this study was to compare a conventional plating method with a faster, simpler method for detection and enumeration of E. coli in samples from naturally contaminated carcasses. The two methods were the conventional pour plate method of the Nordic Committee on Food Analysis; NMKL Method No. 125, and the enzymatic method of SimPlate Coliforms &E. coli. Materials were 588 cotton-cloth samples used for swabbing 100 cm(2) areas on four sites on cattle and lamb carcasses in three commercial abattoirs in Norway. E. coli was detected by at least one of the methods in 270 (46%) of the samples. Forty-five samples (8%) were positive only by SimPlate while 28 samples (5%) were positive only by NMKL125. Cohen's kappa value was 0.74 for detection/non-detection results, which showed a high level of agreement between the two methods. E. coli counts determined by the conventional NMKL125 method showed a high concordance correlation (ccc 0.80, slope 0.99) with most probable number (MPN) values obtained with SimPlate. SimPlate is a rapid and reliable method for detection and enumeration of E. coli and a suitable alternative method for use with swab samples from cattle and lamb carcasses., (Copyright 2010 Elsevier B.V. All rights reserved.)

Alphaherpesviruses infect a wide range of animal species and cause diseases. Cervid herpesvirus 2 (CvHV-2) was originally isolated from reindeer in Finland but the impact of CvHV-2 infections on reindeer remains unclear. CvHV-2 infection could be partly responsible for calf losses as there are indications that it is associated with abortions and neonatal diseases. Previous serosurveys of reindeer (Rangifer tarandus tarandus) have shown that an alphaherpesvirus is circulating among reindeer in Norway. The aim of the present study was to determine the prevalence of CvHV-2 infection among reindeer in various herding districts in Finnmark, the largest reindeer area in Norway, and to identify factors associated with becoming infected with CvHV-2. A total of 3062 serum samples were tested using an ELISA and a sub-set of samples was further tested using a seroneutralization test. The ELISA revealed that 49% of samples were positive. Extrapolation of the results to the total population (111,350 animals; 66% of the Finnmark reindeer population) showed that the seroprevalence in the population was 48%. Seroprevalence varied from 7.6% to 90.7% between districts and was affected by age, weight and population density. ELISA-positive samples neutralized CvHV-2 at serum dilutions greater than those required for neutralization of bovine herpesvirus type 1. It is concluded that CvHV-2 is endemic throughout the reindeer herding districts of northern Norway.

The objective of this work was to examine the impact of subclinical coccidial infection on commercial performance, expressed as a modified European Production Index, in broilers. Performance data, and litter and faecal samples, were collected from two independent observational surveys of Norwegian broilers receiving in-feed narasin during 2000 to 2004. Numbers of oocysts per gram (OPG) of litter collected during rearing (Study 1) or faecal samples collected at slaughter (both studies), and relative frequencies of Eimeria species categories (both studies) were calculated. Polymerase chain reaction-based identification of Eimeria species was performed in Study 2. A definition of flocks at risk of impaired performance associated with coccidia ("risk flock"), using the predominant species and OPG level as criteria, was tested. Coccidia had a significant effect on performance in the first, but not the second study. In Study 1 the following coccidia variables were found to be associated with impaired performance in multivariate models: OPG at slaughter (ordinal), mean OPG during rearing (ordinal) and "risk flock" (binomial). The European Production Index was approximately 9% lower in flocks with infection levels >50 000 OPG at slaughter in Study 1. The composition of coccidial populations shifted between Study 1 and Study 2, from a dominance of medium and large oocysts to a dominance of small oocysts. There was a substantial increase in prevalence of coccidial infection from Study 1 to Study 2, but mean infection levels were similar in the two surveys. The "risk flock" definition was useful as an indicator of coccidia-associated performance loss in Study 1, where subclinical coccidiosis was an important factor. The results suggest that the economic importance of subclinical coccidiosis may vary substantially with time, and they emphasize the need for population studies on the importance and dynamics of specific coccidial infections under different field conditions.

Background: The objectives of the study were to evaluate whether the increase in incidence of campylobacteriosis observed in humans in Norway from 1995 to 2001 was statistically significant and whether different biologically plausible risk factors were associated with the incidence of campylobacteriosis in the different counties in Norway., Methods: To model the incidence of domestically acquired campylobacteriosis from 1995 to 2001, a population average random effect poisson model was applied (the trend model). To case data and assumed risk-factor/protective data such as sale of chicken, receiving treated drinking water, density of dogs and grazing animals, occupation of people in the municipalities and climatic factors from 2000 and 2001, an equivalent model accounting for geographical clustering was applied (the ecological model)., Results: The increase in incidence of campylobacteriosis in humans in Norway from 1995 to 2001 was statistically significant from 1998. Treated water was a protective factor against Campylobacter infections in humans with an IRR of 0.78 per percentage increase in people supplied. The two-level modelling technique showed no evidence of clustering of campylobacteriosis in any particular county. Aggregation of data on municipality level makes interpretation of the results at the individual level difficult., Conclusion: The increase in incidence of Campylobacter infections in humans from 1995 to 2001 was statistically significant from 1998. Treated water was a protective factor against Campylobacter infections in humans with an IRR of 0.78 per percentage increase in people supplied. Campylobacter infections did not appear to be clustered in any particular county in Norway.

Environmental and food contamination with Shiga toxin-producing Escherichia coli (STEC) pose a threat to public health worldwide, with notable geographic differences in incidence of human disease caused by these organisms. The prevalence of E. coli O157 and total stx-positive specimens collected from mature dairy cattle in Ohio and Norwegian dairy farms was compared using identical laboratory methods in a cross-sectional survey. E. coli O157 was isolated from 5/750 (0.66%) of Ohio dairy cows from 4/50 (8%) different herds, whereas E. coli O157 was not isolated from any (0/680) cattle present in 50 Norwegian dairy herds. In contrast, at least one stx-positive faecal sample was identified by PCR on all (50/50) Norwegian farms but only on 70% (35/50) of Ohio farms. Average animal stx prevalence on Ohio farms was also lower; 14% vs. 61% in Ohio and Norwegian herds, respectively. Livestock feed contamination with generic E. coli was uncommon in Norway, 1/50 feeds testing positive, whereas 19/50 (38%) of feeds collected from Ohio farms were contaminated, some as high as 10(5) CFU/g. Despite extreme differences in on-farm management practices between countries, stx appear to be widely disseminated in cattle in both countries, while the human pathogenic O157 serotype is less widely disseminated in Norway than it is in Ohio. Geographic distribution differences of human pathogenic STEC serogroups in the bovine reservoir, as opposed to specific farm management practices affecting on farm STEC prevalence, may be an important defining factor influencing the incidence of human illnesses associated in different areas of the world.

The Norwegian Action Plan against Campylobacter in broilers was implemented in May 2001 with the objective of reducing human exposure to Campylobacter through Norwegian broilers. From each flock, samples collected at the farm about one week prior to slaughter, and then again at the slaughter plant, are examined for the presence of Campylobacter. All farmers with positive flocks are followed up with bio-security advice. Sampling of broiler products at retail level is also included in the Action Plan. The aim of this study was to evaluate the existing sampling and culturing methods of the Norwegian Action Plan against Campylobacter in broilers. The material collected was pooled faecal samples, pooled cloacae samples and caecae samples from individuals. The highest number of positives, from culturing of the pooled faecal samples, the pooled cloacae swabs and the caecae swabs from individuals, were obtained at incubation temperature 41.5 degrees C. When comparing the results at incubation temperature 37 and 41.5 degrees C, the faecal samples from the farms demonstrated a high concordance, with a kappa value of 0.88. The results from culturing cloacae swabs and caecae samples from slaughter plant level at two temperatures did not agree very well with a kappa value of 0.21 and moderate value of 0.57, respectively, but were both disconcordant at a level of 0.05. Modelling farm level data indicated that if increasing the number of pooled samples per flock from two (in existing regime) to three, the flock sensitivity increases from 89% to 95%. Modelling of slaughter plant data indicated that three pooled cloacae swabs are needed to identify 90% of the positive flocks. The results from the modelling of caecae data indicated that samples from seven individuals are sufficient to identify 90% of the positive flocks and caecae samples could thus be an alternative to cloacae sampling at slaughter plant level.

A retrospective cost-benefit analysis was carried out on the Norwegian bovine virus diarrhoea (BVD) control and eradication strategy, for the years 1993-2003. Information regarding the control cost input parameters was gathered from the cattle industry (TINE Norwegian Dairies, GENO Breeding and AI association, and GILDE Norwegian Meat), The National Animal Health Authorities and The Veterinary Institute. We accounted for variable costs (both direct costs associated with the control, and those costs carried by the farmers as a consequence of the control program). The benefit was estimated as the difference between the assumed losses without control - represented overall as 10% increase of the observed 1993 BVD virus infection level - and the observed losses during the control period. An estimate of the financial losses associated with the BVD virus (BVDV) infection was based on studies of the herd level effects on health, reproduction, and production in dairy herds with evidence of recent BVDV infection. We used a stochastic simulation model to account for the total uncertainty in both the control cost and financial loss estimates. The annual net benefits over the 10 years of BVD control were discounted to a 1993 net present value (NPV). The median NPV of the BVD control, nationally, was estimated at 130 million NOK with a distribution of the NPV ranging from +51 to +201 million NOK (5th and 95th percentiles, respectively). Out of the total control costs the farmers and the farmer-owned industries (the co-operatives) had carried about 62% of these costs; however, the farmers were also the main beneficiaries. The Norwegian experience shows a robust cost-efficiency for a BVDV eradication strategy; this stands in sharp contrast to earlier studies where the results were not supportive. Even though every cattle population and country is unique, the Norwegian findings and experiences should have wider implications.

The occurrence and geographic distribution of species belonging to the genera Alternaria and Fusarium in grains of reduced and of acceptable quality were studied post-harvest in 1997 and 1998. A total of 260 grain samples of wheat, barley and oats was analysed. The distribution of Alternaria and Fusarium spp. varied significantly in samples of reduced quality compared with acceptable samples. Alternaria spp. dominated in the acceptable samples with A. infectoria group as the most frequently isolated and most abundant species group of this genus while Fusarium spp. dominated in samples of reduced quality. The most frequently isolated Fusarium spp. from all samples were F. avenaceum, F. poae, F. culmorum and F. tricinctum. Other important toxigenic Fusarium spp. isolated were F. graminearum and F. equiseti. The infection levels of F. graminearum and F. culmorum were significantly higher in the samples of reduced quality. The results indicated a negative interaction between F. graminearum and Alternaria spp. as well as between F. graminearum and other Fusarium spp., (Copyright 2003 Elsevier B.V.)

The present prospective study included 106 horses referred to the Department of Large Animal Sciences, The Norwegian School of Veterinary Science, as non-responders to the initial colic treatment in general practise. In 14 of these cases a required surgical treatment was not performed due to economical or other reasons and were excluded from the study. Clinical and laboratory data were obtained at the arrival in the hospital. The outcome for all analyses was survival/ non-survival. A multivariable logistic regression was performed. The analyses were used in medically (46 horses) and surgically treated cases (46 horses) separately. The same analyses were also run for all 92 horses in a simulated "field" situation, where only clinical variables and D-dimer values were included. The fraction of survivors was 78% in the medical and 48% in the surgical cases. In total 63% of the horses survived. In the final multivariable logistic regression model packed cell volume (PCV) was the only important predictor for medically treated cases, and heart rate and presence of hyperaemic or cyanotic mucous membranes were the predictors in the surgically treated cases as well as in the simulated "field" situation. In conclusion, traditional variables as heart rate, mucous membranes and PCV were the important predictors for the outcome in hospitalised colic cases.

The agreements between various culturing-method combinations and specimens to detect sheep naturally infected by Salmonella enterica IIIb 61:k:1,5,(7) were tested. Rectal swabs, faecal samples and ileo-caecal lymph nodes were collected from each individual. Rectal swabs called "group I" (n = 54) were cultured directly on selective media (selenite cysteine, SC). Rectal swabs called "group II" (n = 47) were pre-incubated in buffered peptone water. The four other combinations of culturing-method and specimen (one lymph node and three faecal) in each of the two groups were cultured directly on SC. The results from all the combinations of method and specimens were compared to the result from the rectal-swab test by kappa and McNemar's chi-square. Kappas for the agreement between rectal swabs and faecal sample tests were only 0.4. The lymph-node test agreed even-more poorly, with mean kappa value -0.02. The McNemar's test revealed that the discordancies between the rectal-swab test and all of the other tests went in both directions but sometimes did show bias (directionality) in the discordancies.

Rectal swabs from healthy cats and dogs, and from dogs and cats with clinical diarrhoea were collected approximately every third month from May 2000 to June 2001 from six small-animal practices throughout Norway. A questionnaire was filled in for each animal. Of the 301 healthy cats sampled, 54 (18%) were positive for Campylobacter, compared to 5 out of 31 (16%) cats with diarrhoea. Campylobacter jejuni was isolated from 11 (3%), C. upsaliensis from 42 (13%) and C. coli from 2 (0.6%) of the cats sampled. Isolates from four cats (1%) could not be specified. Of the 529 healthy dogs, 124 (23%) were positive for Campylobacter, compared to 18 of 66 (27%) dogs with diarrhoea. C. jejuni was isolated from 20 (3%) and C. upsaliensis from 117 (20%) of the dogs sampled. Isolates from five dogs (0.8%) could not be specified. Eighteen out of the 20 investigated C. upsaliensis samples were resistant to streptomycin. The clinically healthy animals were included in the analysis to identify factors associated with Campylobacter prevalence. The cat model had low classification ability. The dog-data model indicated increased odds of infection with Campylobacter for dogs

Population data and apparent prevalence data from the Salmonella surveillance and control program in pigs (NSSCP) from 1998 and 1999 were used in a simulation model to evaluate the efficacy of the program. The model consists of three parts: modelling of individual prevalence at the abattoir (abattoir part), modelling of the number of sampled herds of different sizes when carcasses are randomly sampled at the abattoir (sampling strategy part) and finally, modelling of the within herd prevalence (within herd part). A total of 136,550 sows and 2,866,550 finishing pigs slaughtered, 4446 herds and 11 herds positive for Salmonella in 1994/1995-2000 were included in the abattoir part, sampling strategy part and the within herd part of the model, respectively. The abattoir part showed an average estimated prevalence of Salmonella in sows and finishing pigs of (median) 0.4% (5-95 percentiles = 0.03-2%) and 0.1% (0.04-0.2%) respectively. The estimated number of infected sow carcasses that entered the market was 502 (37-2157) while the estimated number of finishing pig carcasses was 2919 (1218-5771). The probability of being sampled for the 10% smallest herds was (mean) 1.9% (1.6-2.2), to 25% (24.7-26.5%) for the 10% largest herds. The within herd prevalence was estimated to be from 1% to 4% for Norwegian pig herds. The conclusions drawn from this evaluation are that the NSSCP does not have any significant consumer protection effect, and that the documentation could be done more effectively using the herd rather than the individual animal as the unit of sampling. Sampling should focus on the larger herds supplying most of the meat on the market and on herds that produce breeding sows and piglets and thus can contribute to the spread of Salmonella among herds.

Fifty randomly selected sheep flocks from a region in central Norway were sampled in December 1999 to determine the flock prevalence of Salmonella enterica subspecies diarizonae serovar 61:k:1,5,(7) (S. IIIb 61:k:1,5,(7)). From each flock, 15-41 rectal swabs were collected from individual sheep of different age groups and examined for S. IIIb 61:k:1,5,(7). Positive flocks were visited again in January-April and each time, rectal swabs from the same animals were collected and examined for this specific serovar. Seven flocks (14%; 95% CI 6.3-27%) were positive for S. IIIb 61:k:1,5,(7) in December; in all, 10 sheep out of the 1233 (0.8%) were positive at the first sampling. From the seven positive flocks, six, five, six, and nine animals were positive in January, February, March, and April, respectively. Of the total 21 individual sheep tested positive from January to April, 15 were >2 years old (OR(ex)=3.26; 1.1-10.2). Six out of the seven positive flocks were large flocks (>117 ewes). Sharing of rams between flocks did not seem to be a risk factor for the presence of S. IIIb 61:k:1,5,(7) in a flock.

Dairy herds in Møre and Romsdal County, Norway (regarded as initially free from the bovine virus diarrhoea virus (BVDV) infection) were studied retrospectively from 1992 to 1996. The herd reproductive performance (time to first calving, calving interval, and number of breeding services) was investigated for a potential effect of BVDV sero-conversion. The herd culling pattern--possibly affecting the above measurements--was included for investigation. Two different statistical models were used: the generalised estimating equation (GEE) method and multilevel modelling using Gibbs sampling. Though slightly different estimates resulted, both models agreed on an effect of BVDV in the second year after sero-conversion on the herd average time to first calving by--on an average-- 14-16 days. In subsets of case herds testing positive for BVDV antibodies among young stock, the impact on time to first calving tended to be more pronounced by an additional increase of 18 days. No effect on the number of breeding services for heifers or cows was observed (indicating a need to search for other determinants than reduced conception risk). There appeared to be no effect of BVDV on the herd average calving interval. There was a tendency for a higher risk for reporting animals lost/died in sero-converted herds, which we believe might be related to the occurrence of mucosal disease.

The aim of this study was to describe the occurrence of shiga toxic genes (stx) in Norwegian sheep herds, and to identify herd management factors related to the occurrence of stx in herds. Faecal samples from 124 sheep-herds were collected at abattoirs in 1998. Pooled samples from lambs and from ewes were screened for stx by a PCR method directly on faeces. Of the 124 herds, 61 were positive for stx, giving an overall herd-prevalence of 49%. Twenty-one of the 61 positive herds were positive both in lamb and ewe samples, 24 only in lamb samples and 16 only in ewe samples. There was no difference in prevalence between regions. From the 21 herds positive both in lamb and ewe samples, stx encoding E. coli were detected in 18 herds using hydrophobic grid membrane filters and subsequent colony hybridization. Information about management factors was collected by telephone interviews. Having cattle at the same farm turned out to be a possible risk factor, with an Odds Ratio of 9.9 (CI 1.2 --> infinity).

We investigated the operational performance (sensitivity and specificity) of a bovine virus diarrhoea virus (BVDV) antibody ELISA bulk-tank milk test for predicting the herd BVDV antibody status in young stock (as a relatively precise indicator of active BVDV infection). The study was based on results from the annual screenings under the Norwegian bovine virus diarrhoea (BVD) control and eradication program, lasting from 1993 to 1997. Empirical information from these annual screenings was the basis for prior assumptions about the true prevalence of young-stock-positive herds. Assumptions about prior distributions for sensitivity and specificity were based on the literature. Improved posterior test performance estimates were achieved applying a Bayesian approach using Gibbs sampling simulation. The simulations were run separately for each year, and yielded median values for sensitivity of 87% at the cut-off used in the BVD program. The posterior distributions were wide indicating much uncertainty in these estimates. The specificity estimates ranged from 79 to 92% and had narrower posterior estimates. The estimates differed by year. When running the same simulation procedures at a lower cut-off --after altering the sensitivity and specificity priors--the median sensitivity estimates increased to about 95%; the median specificity ranged from 71 to 83%. Due to low prevalence, the Bayesian method lacked power to assess the test sensitivity. A technically simpler descriptive graphing procedure (based on empirical information) provided equally useful insight into the bulk-tank milk test performance.

An epidemic of acute respiratory disease associated with bovine respiratory syncytial virus (BRSV) occurred during the winter and spring of 1995 in two neighbouring veterinary districts in the south-eastern part of Norway. The objective of this study was to describe the time course of the outbreak associated with BRSV in the cattle herds, and to determine the association between selected herd factors and the risk of experiencing a herd outbreak of acute respiratory disease. Data from 431 cattle herds on the dates of disease occurrence, location of the farms, herd size, age profile and production type were collected retrospectively for 1995. The risk of acute respiratory disease occurring in a cattle herd was related to the herd size as well as the type of production, with an expressed interaction between these two variables. From the Cox proportional-hazards model, the risk of a herd outbreak in a mixed herd of 20 animals was estimated to be 1.7-times greater than in a dairy herd and 3.3-times greater than a beef herd (reference category) of a comparable size. On increasing the herd size to 50 animals, the risk increased 1.3-fold for a mixed herd, 3.3-fold for a dairy herd, and 2.1-fold for a beef herd, compared to the risk for a corresponding type of herd of 20 animals.

A dynamic simulation model was used to assess the long-term effect of importing beef from an area with a high prevalence of Taenia saginata among cattle. The input of the model was from a Monte Carlo simulation model. The model predicted substantial increases in the prevalence of T. saginata in domestic cattle and in the incidence and prevalence of infections in humans that would last for more than one decade even if importation of infected beef was stopped after 2 years. The results were strongly influenced by various assumptions about proportion of human carriers infected abroad. Only in a scenario where 99% of domestic carriers are infected abroad did the simulation results show no dramatic ecological effect of importation of the beef. If the model's predictions are realistic, then an increase in the prevalence of T. saginata infections in cattle will be observed in and after 1999.

A Monte Carlo risk assessment model was developed to estimate the public health risk of importing prime cuts of beef infested with Taenia saginata to Norway from an endemic area in southern Africa. The model predicted that 21 (lower 5% = 1, upper 95% = 56) viable cysts would be present in domestic prime cuts during 1996 and 1997, with 8 (0 to 21) of them being ingested without sufficient heat treatment to kill the parasite. These cysts were expected to cause 2 (0 to 7) human infections. Corresponding figures for the imported prime cuts were 1,260 (99 to 2,900) viable cysts, 462 (37 to 1,065) ingested without sufficient heat treatment, causing 132 (8 to 361) human infections. The model was sensitive to the uncertainties related to the estimates of probabilities of cysts being viable and the probability of their causing infection in humans. The public health impact from consuming imported beef is not large, but the model illustrates how imported cuts may change the epidemiological pattern of a disease even when the import constitutes only 3% of the prime cuts consumed.

The Norwegian bovine virus diarrhoea (BVD) control-and-eradication program performed annual testing of the national cattle population since its first screening in January 1993. A bulk-tank milk ELISA antibody test was used for the initial screening of dairy herds. Based on the annual bulk-tank milk-test result, a binary variable denoting herd sero-conversion (a surrogate measure for incidence) was created. The count of herds with sero-conversion in each community was regressed on year and the initial herd-sero-prevalence for each community in a Poisson hierarchical trend model - modelling the risk of sero-conversion. By using this modelling approach, estimates of trend specific for each hierarchical level of organisation were included in the trend model (community, veterinary district and county) could be estimated. The main BVD trend showed a steadily declining sero-conversion risk. The communities in the highest herd-sero-prevalence quartile in 1993 continued to have the highest sero-conversion risk throughout the study period--decreasing from an average predicted sero-conversion risk in 1993 of 0.12 (95% CI; 0.10, 0.13) to 0.02 (0.007, 0.04) in 1997. There was an expressed variation in the level of sero-conversion for all the three hierarchical levels, but the trend only varied at the lowest level (community).

A higher herd prevalence of antibodies (ELISA) to Yersinia enterocolitica O:3 was found in conventional slaughter production (86.0% seropositive herds) than in conventional farrow-to-finish herds (53.1% seropositive herds). The herd prevalence of antibodies to Y. enterocolitica in multiplying herds (56.1%) was similar to the level in the conventional farrow-to-finish herds. An epidemiological study in conventional pig herds demonstrated that farrow-to-finish production (odds ratio, OR = 0.15) was an important protective factor. Using under-pressure ventilation (OR = 0.33) and manual feeding of slaughter pigs (OR = 0.44) also lowered the herd prevalence. The most expressed risk factor was using an own farm vehicle for transport of slaughter pigs to abattoirs (OR = 12.92). Separation between clean and unclean section in herds (OR = 2.67), daily observations of a cat with kittens on the farm (OR = 2.41) and using straw bedding for slaughter pigs (OR = 2.25) were other factors that increased the risk. In conclusion, the epidemiological data suggest that it is possible to reduce the herd prevalence of Yersinia enterocolitica O:3 by minimising contact between infected herds and non-infected herds. Further, attempts to reduce the prevalence at the top levels of the breeding pyramids may be beneficial for the industry as a whole. The meat industry may use serological tests as a tool to lower the prevalence in the pig population by limiting the contact between seropositive and seronegative herds. However, because of the high prevalence of Y. enterocolitica in pig herds, a strict slaughter hygiene will remain an important means to reduce carcass contamination with Y. enterocolitica O:3 as well as other pathogenic micro-organisms.

In a study of lambs from 194 sheep flocks from different areas of Norway, 44.3% of the flocks were found seropositive against Toxoplasma gondii using an ELISA test, with antibodies found in 16.2% of the 1940 individual animals. The risk factors for the occurrence of antibodies to Toxoplasma gondii found in the multivariate logistic regression were: daily presence of a young cat in the sheep house (Odds ratio, OR = 4.11, 95% CI = 1.01-19.7); 'atypical' grazing of lambs (OR = 6.35, CI = 2.36-17.11); use of mouse poison in the sheep house (OR = 2.26, CI = 1.02-5.00); farm situated at an altitude > 100 meters above seal level (101-250 m: OR = 1.20, CI = 0.49-2.92; 251-500 m: OR = 4.97; CI = 2.04-12.0; > 500 m: OR = 3.66, CI = 1.33-10.1). A lower risk was found for flocks with perforated metal floors in the sheep house (OR = 0.47, CI = 0.23-0.96) and timber construction of the sheep house (OR = 0.34, CI = 0.15-0.80). Based on these findings it was recommended that farmers avoid keeping young cats in the sheep houses, that close-to-farm grazing be kept to a minimum and that perforated metal floors be used in the sheep houses. However, with such a high seroprevalence, the proposed measures alone would not reduce the occurrence of Toxoplasma in lambs to a level where undercooked lamb can be consumed without posing an unacceptable risk for some consumer groups.

To investigate if there is a reservoir of Escherichia coli O157 in Norwegian cattle, faecal samples from 197 cattle herds were screened for E. coli O157 by the use of immunomagnetic separation (IMS) and PCR during the 1995 grazing season. Six E. coli O157:H-isolates were detected in two herds, one isolate in one and five in the other. The isolates carried the stx1, stx2, and eae genes, and a 90 MDa virulence plasmid. They were toxinogenic in a Vero cell assay. From 57 other herds, 137 faecal samples were positive for stx1 and/or stx2 genes detected by PCR run directly on IMS-isolated material. Among these samples, stx2 were the most widely distributed toxin encoding genes. No difference was found among milking cows and heifers in the rate of stx1 and/or stx2 in positive samples.

The prevalence of serum antibodies against Norwalk virus among military recruits in Norway was investigated using an enzyme-linked immunosorbent assay (ELISA). A total of 1017 sera were assayed for anti-Norwalk virus total antibodies (ig), of which 300 (29.5%) were positive. Of 227 positive sera, 10.6 and 15.4% were positive for IgA and IgM, respectively, while 2.2% were positive for both. The prevalence of antibodies against Norwalk virus in south-east Norway was significantly higher than that in northern Norway.

An epidemiological investigation was conducted to identify risk factors related to hygiene and husbandry practices which determine the introduction of Campylobacter spp. into broiler chicken flocks. All 176 broiler farms in an area in southeastern Norway participated in the study. Each farm was represented by one flock selected at random during a one-year period. The flocks were examined for campylobacter colonization at slaughter, and the flock managers were subsequently interviewed about hygiene and husbandry practices. Campylobacter spp. were recovered from 32 (18%) of the flocks. The proportion of colonized flocks varied geographically and seasonally with a peak in the autumn. The following variables were found to be independently associated with an increased risk of campylobacter colonization using logistic regression analysis: (i) feeding the broilers undisinfected water (odds ratio (OR) = 3.42, P = 0.045), (ii) tending other poultry prior to entering the broiler house (OR = 6.43, P = 0.007), (iii) tending pigs before entering the house (OR = 4.86, P = 0.037), (iv) geographic region (Hedmark versus Ostfold county) (OR = 2.91, P = 0.023, (v) season (autumn versus other seasons) (OR = 3.43; P = 0.008). Presence of rats on the farm was associated with an increased risk, but this factor did not reach statistical significance (OR = 3.96, P = 0.083). Preventive measures should include disinfection of drinking water and strict hygienic routines when the farm workers enter the rearing room. The results indicate that disinfection of drinking water is the preventive measure most likely to have the greatest impact on the prevalence of campylobacter among broiler chicken flocks in the study area (population attributable fraction = 0.53).

In 1989 and 1990, a case-control study designed to identify risk factors for sporadic infections with thermotolerant Campylobacter bacteria was conducted in three counties in southeastern Norway. The investigation was confined to infections which were acquired in Norway. A total of 52 bacteriologically confirmed cases and 103 controls matched by age, sex, and geographic region were interviewed. The following risk factors were found to be independently associated with illness in conditional logistic regression analysis: consumption of sausages at a barbecue (odds ratio [OR] = 7.64; P = 0.005), daily contact with a dog (OR = 4.26; P = 0.024), and eating of poultry which was brought into the house raw (frozen or refrigerated) (OR = 3.20; P = 0.024). The risk associated with consumption of sausages at a barbecue could not be attributed to cross-contamination from poultry products. By univariate analysis, consumption of poultry which was brought raw and frozen was associated with illness (OR = 2.42; P = 0.042), even though freezing substantially reduces the number of viable campylobacters. When poultry consumption was examined by country of origin, eating of poultry produced in Denmark or Sweden was strongly associated with illness (OR = 13.66; P = 0.014), whereas consumption of poultry produced in Norway was not (OR = 1.33; P = 0.41).

The prescribing of drugs for food-producing animals in Norway was investigated with special emphasis on written information given about withdrawal times. The study was designed as a cross-sectional prescription survey. Of 1518 prescriptions for food-producing animals, it was concluded that 1224 of the prescriptions were for drugs requiring withdrawal times for meat, milk or eggs. Of these 1224 prescriptions, 82.8% were for veterinary preparations, 6.6% were for human preparations and 10.6% were for other drugs. For 20.8% of the prescriptions, information about withdrawal time(s) was missing. For prescriptions for veterinary preparations this figure was 5.9%, and for prescriptions for human preparations and other drugs 95.1% and 90.8%, respectively. For veterinary preparations approved for the intended species, as many as 99.2% gave information about withdrawal times on the drug container label. Lack of information about withdrawal times might give rise to drug residues in food for human consumption and thus pose a potential hazard to human health.