Designing a risk-based surveillance program for Mycobacterium avium ssp. paratuberculosis in Norwegian dairy herds using multivariate statistical process control analysis.

Surveillance programs for animal diseases are critical to early disease detection and risk estimation and to documenting a population's disease status at a given time. The aim of this study was to describe a risk-based surveillance program for detecting Mycobacterium avium ssp. paratuberculosis (MAP) infection in Norwegian dairy cattle. The included risk factors for detecting MAP were purchase of cattle, combined cattle and goat farming, and location of the cattle farm in counties containing goats with MAP. The risk indicators included production data [culling of animals >3 yr of age, carcass conformation of animals >3 yr of age, milk production decrease in older lactating cows (lactations 3, 4, and 5)], and clinical data (diarrhea, enteritis, or both, in animals >3 yr of age). Except for combined cattle and goat farming and cattle farm location, all data were collected at the cow level and summarized at the herd level. Predefined risk factors and risk indicators were extracted from different national databases and combined in a multivariate statistical process control to obtain a risk assessment for each herd. The ordinary Hotelling's T(2) statistic was applied as a multivariate, standardized measure of difference between the current observed state and the average state of the risk factors for a given herd. To make the analysis more robust and adapt it to the slowly developing nature of MAP, monthly risk calculations were based on data accumulated during a 24-mo period. Monitoring of these variables was performed to identify outliers that may indicate deviance in one or more of the underlying processes. The highest-ranked herds were scattered all over Norway and clustered in high-density dairy cattle farm areas. The resulting rankings of herds are being used in the national surveillance program for MAP in 2014 to increase the sensitivity of the ongoing surveillance program in which 5 fecal samples for bacteriological examination are collected from 25 dairy herds. The use of multivariate statistical process control for selection of herds will be beneficial when a diagnostic test suitable for mass screening is available and validated on the Norwegian cattle population, thus making it possible to increase the number of sampled herds.

The prescription rate of antibacterial agents in dogs in Norway - geographical patterns and trends during the period 2004-2008.

The aim of the present study was to describe the prescription rate and patterns of antibacterial agents in the Norwegian dog population in relation to time and place during 2004-2008. Prescription data were collected from the Norwegian prescription database (NorPD), whereas an estimate of the dog population was obtained from the Norwegian Kennel Club (NKK). Maps of the geographical prescription rate patterns were generated in the software ArcGIS 9.2. This study indicates an increased usage of antibacterial agents in dogs in Norway during the study period in which antibacterial agents for systemic use and especially the combination amoxicillin and clavulanic acid accounted for the major part. Among antibacterial agents defined as critically important for human medicine, an increase was observed in the prescription rate of quinolones. The geographical prescription rate patterns were stable during the study period, which indicated that the identified increase in usage of antimicrobial agents occurred all over the country, but that there were regional differences in the prescribing behaviour. Prescription data from the NorPD of antibacterial agents to dogs can be used as a basis to perform a risk-based sampling approach to detect emerging antimicrobial resistance in the dog population.

The prevalence and spatial clustering of Neospora caninum in dairy herds in Norway.

The aims of this study were to estimate the national herd prevalence and the general spatial distribution of Neospora caninum infection in Norwegian dairy cattle. Bulk milk samples from 1657 randomly selected dairy herds were analysed by iscom ELISA for the presence of N. caninum specific antibodies. The national herd prevalence was estimated to be 0.7% (95% CI: 0.3-1.2%), which is the lowest national herd prevalence reported in Europe. In addition, we included a subpopulation study in which all 400 herds in the Oslo, Akershus and Østfold counties were sampled, and we found a herd prevalence of 1.8%. In the national herd study, a significant cluster of N. caninum infected herds was identified in Jaeren, on the south west coast of Norway. Jaeren has the highest density of farm animals in the country as well as climatic conditions that favour parasite survival. Dairy herds in this region had a 52 times higher relative risk of being N. caninum positive than dairy herds in other parts of Norway. This indicates that even though N. caninum infection is of minor importance in Norway, infection might cause abortion problems in high risk areas.

Space-time patterns of Campylobacter spp. colonization in broiler flocks, 2002-2006.

This study was performed to investigate space-time patterns of Campylobacter spp. colonization in broiler flocks in Norway. Data on the Campylobacter spp. status at the time of slaughter of 16 054 broiler flocks from 580 farms between 2002 and 2006 was included in the study. Spatial relative risk maps together with maps of space-time clustering were generated, the latter by using spatial scan statistics. These maps identified the same areas almost every year where there was a higher risk for a broiler flock to test positive for Campylobacter spp. during the summer months. A modified K-function analysis showed significant clustering at distances between 2.5 and 4 km within different years. The identification of geographical areas with higher risk for Campylobacter spp. colonization in broilers indicates that there are risk factors associated with Campylobacter spp. colonization in broiler flocks varying with region and time, e.g. climate, landscape or geography. These need to be further explored. The results also showed clustering at shorter distances indicating that there are risk factors for Campylobacter spp. acting in a more narrow scale as well.

Antimicrobial resistance in Campylobacter jejuni from broilers and broiler house environments in Norway.

Antimicrobial susceptibility in Campylobacter jejuni collected from the environment outside four broiler houses (n = 63) and from the environment inside these broiler houses (including broiler droppings) (n = 36) from May to September 2004 was studied and compared with isolates from Norwegian broilers analyzed within the frame of the Norwegian monitoring program of antimicrobial resistance in feed, food, and animals (NORM-VET) in 2004 (n = 75). The MICs of oxytetracycline, ampicillin, erythromycin, gentamicin, enrofloxacin, and nalidixic acid were obtained by the broth microdilution method VetMIC. The present study, which to our knowledge is the first Norwegian study on the occurrence of antimicrobial resistance in Campylobacter spp. from the environment of broiler houses, revealed a very low occurrence of antimicrobial resistance in C. jejuni from the broilers and broiler house environments studied. All isolates originating from the four broiler houses studied were susceptible to all the antimicrobial agents tested, except for one isolate from the outdoor environment (courtyard soil), which was resistant to oxytetracycline (MIC, 8 mg/liter). For the isolates from broilers (NORM-VET), low prevalences of resistance to oxytetracycline (1.3%) and ampicillin (4%) were observed. No quinolone resistance was observed. The results for the broiler isolates are in agreement with the earlier findings of a very low prevalence of resistance in Campylobacter from broilers in Norway, which reflects the low usage of antimicrobials in Norwegian broiler production. Furthermore, the present data are in accordance with antimicrobial susceptibility data for C. jejuni from domestically acquired human cases.

Antimicrobial resistance in Campylobacter jejuni from humans and broilers in Norway.

In this study comprising isolates from 2001 to 2003, resistance was considerably more widespread among Campylobacter jejuni from humans infected abroad than infected within Norway. The discrepancy was particularly notable for fluoroquinolone resistance (67.4% vs. 6.5%). This is probably a reflection of a low resistance prevalence in Norwegian broiler isolates (1.2% fluoroquinolone resistant).

The effect of an outbreak of respiratory disease on herd-level milk production of Norwegian dairy farms.

This study was done to evaluate the effect of an outbreak of acute respiratory disease associated with bovine respiratory syncytial virus (BRSV) on the daily milk yield per cow in Norwegian dairy-cattle farms. Retrospective data from 184 dairy herds located in two neighbouring veterinary districts during the study period (December 1994-May 1995, during which an epidemic of acute respiratory disease associated with BRSV occurred in this area) were analysed. Data on the bulk-milk deliveries and the date of the outbreak were collected at herd level, whereas information on calving dates and parity was collected at cow-level. The effect of the herd outbreaks on the daily milk yield was analysed with a repeated-measurement approach. The average daily milk loss was estimated to be 0.70kg per cow for 7 days after a herd outbreak (compared with the period >1 week prior to an outbreak), adjusted for the herd-level lactation stage, parity and their interaction term. We consider the estimated milk loss associated with a herd outbreak of epidemic respiratory disease to be of minor importance.

Impact of sex and psychological factors on the water loading test in functional dyspepsia.

BACKGROUND: The pathogenesis of upper abdominal symptoms in patients with functional dyspepsia (FD) is still unclear. The water loading test (WLT) is a new method for evaluation of gastric function. Our aim was to determine the impact of sex, age and psychological factors on the results of WLT in FD patients, FD-subgroups and healthy controls (HCs), and to evaluate the safety of the test. METHODS: Fifty-six HCs and 35 consecutive patients with FD drank mineral water (100 ml/min) until intolerable. Serum samples for sodium, potassium and creatinine was taken before and after drinking. Water quantity was registered and symptoms were assessed after maximal water intake and 30 min later using a VAS scale. Participants also completed questionnaires measuring psychological general well-being (PGWB) and gastrointestinal symptoms (GSRS and Mearin score). RESULTS: Healthy men drank more than healthy women, 2350 +/- 105 ml versus 1860 +/- 100 ml (P < 0.01), and the same gender difference was noted in FD patients, 1770 +/- 115 ml versus 1180 +/- 110 ml (P < 0.01). Maximal water intake was significantly higher in HC than in FD patients, both in males (P < 0.001) and females (P < 0.0001). Age had no impact on drinking capacity. FD patients had more symptoms 30 min after maximal water intake than HCs. Serum sodium decreased from 141 +/- 0.3 mmol/l to 138 +/- 0.5 mmol/l. Two of the assessed psychological factors, general health and depressed mood, correlated with water intake in FD patients (Rho = 0.47, P < 0.01 respectively Rho = 0.41, P < 0.05). CONCLUSION: WLT is a useful, simple and safe test for evaluating symptoms in FD patients. Sex, but not age affects the results of the WLT. Furthermore, psychological factors must also be taken into consideration when interpreting the WLT.

Geographical Information System (GIS) as a tool in surveillance and monitoring of animal diseases.

In the veterinary epidemiology, the advantage of mapping the locations of farms and other facilities with animals is obvious. In an outbreak of a disease it could make the management of the situation easier, and it could also provide a tool to evaluate different strategies to prevent the spread of infectious diseases. This paper aims to describe and give an overview of the possibilities and potential uses of a Geographical Information System (GIS) in the field of surveillance and monitoring of animal diseases. The following areas in which GIS and special GIS-functions could be incorporated are presented: recording and reporting information, epidemic emergency, cluster analysis, modelling disease spread, and planning control strategies. Different sources of data; geographical data, farm locations and disease information, used in the development of the GIS at the National Veterinary Institute in Norway are thoroughly described in the paper. Further, it presents a few examples where the GIS has been applied to studies of epidemiology and surveillance of animal diseases in Norway, which shows the significant value of GIS in these areas. At the same time, the incorporation of GIS in this field shows the scarcity of the data available, which should encourage improvement in the data recording and the quality of the registries.

Risk factors for epidemic respiratory disease in Norwegian cattle herds.

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 space-time cluster investigation of an outbreak of acute respiratory disease in Norwegian cattle herds.

Outbreaks of acute respiratory disease occurred in several cattle herds in the south-east regions of Norway during the winter and spring of 1995. The present study was conducted to investigate the temporal and spatial dynamics of the occurrence of acute respiratory disease between January and April 1995 in the affected cattle herds, in two neighbouring counties in Norway. This was done to assess the possible role of an infectious agent in these outbreaks, as well as to investigate the possibility of transmission between neighbouring herds. During the study period, a total of 190 (19.8%) outbreaks occurred in 955 cattle herds located in the defined study area. Descriptive maps of the spatial and spatio-temporal patterns of the outbreak were generated, and two different statistical tests of space-time interaction (the Knox test and k-nearest neighbour test) and a cluster-detection test (the space-time scan statistic) were used. The results of all the space-time interaction tests strongly suggested that the case herds were clustered in time as well as in space. In addition, the space-time scan statistic defined the most-likely cluster to be located within the second veterinary district (Toten where the disease occurred) during 9-15 weeks in 1995. The relative risk of a herd being infected inside the most-likely cluster compared with the surrounding study area was estimated to be 3.59 (p=0.001). The transmission rate between neighbouring farms therefore appeared to have been higher within this cluster than in the surrounding study area. This study supports the hypothesis that one common source of infection was involved in the outbreaks during the study period.