J. Niza-Ribeiro

Risk factors for Salmonella spp in Portuguese breeding pigs using a multilevel analysis.

Salmonella is the second most frequent cause of foodborne illness in the European Union (EU), so EU enforced legislation to achieve a reduction in Salmonella prevalence in the swine sector. To set the reduction target each country carried out a baseline survey to estimate Salmonella prevalence. The aim of our study was to identify risk factors for the presence of Salmonella in breeding pigs based on the data of the Baseline Study for Salmonella in Breeding Pigs in Portugal. In total, 1670 pen fecal samples from 167 herds were tested by culture and 170 samples tested positive. Along with the collection of the samples a survey was applied to collect information about the herd management and potential risk factors. Multilevel analysis was applied to the data using generalized linear mixed models and a logit link function. The outcome variable was the presence/absence of Salmonella in the pen fecal samples. The first level was assigned to the pen fecal samples and the second level to the herds. The results showed significant associations between Salmonella occurrence and the factors (p<0.05): maternity pens versus mating pens (OR=0.39, 95%CI: 0.24-0.63), feed from external or mixed source versus home source (OR=2.81, 95%CI: 1.19-6.61), more than 10 animals per pen versus 10 animals per pen (OR=2.02, 95%CI: 1.19-3.43), North Region versus Alentejo Region (OR=3.86, 95%CI: 1.08-13.75), rodents control (OR=0.23, 95%CI: 0.090-0.59), more than 90% of boars homebred or no boars versus more than 90% of boars from an external source (OR=0.54, 95%CI: 0.3-0.97), semen from another herd versus semen from insemination centers (OR=4.47, 95%CI: 1.38-14.43) and herds with a size of 170 or more sows (OR=1.82, 95%CI: 1.04-3.19). This study offers very relevant information for both the Portuguese veterinary authorities and the pig farmers currently developing control programmes for Salmonella. This is the first study providing evidence for semen and boars source as risk factors for Salmonella in breeding pigs.

Assessing risk profiles for Salmonella serotypes in breeding pig operations in Portugal using a Bayesian hierarchical model

BackgroundThe EU Regulation No 2160/2003 imposes a reduction in the prevalence of Salmonella in pigs. The efficiency of control programmes for Salmonella in pigs, reported among the EU Member States, varies and definitive eradication seems very difficult. Control measures currently recommended for Salmonella are not serotype-specific. Is it possible that the risk factors for different Salmonella serotypes are different? The aim of this study was to investigate potential risk factors for two groups of Salmonella sp serotypes using pen faecal samples from breeding pig holdings representative of the Portuguese pig sector.MethodsThe data used come from the Baseline Survey for the Prevalence of Salmonella in breeding pigs in Portugal. A total of 1670 pen faecal samples from 167 herds were tested, and 170 samples were positive for Salmonella. The presence of Salmonella in each sample (outcome variable) was classified in three categories: i) no Salmonella, ii) Salmonella Typhimurium or S. Typhimurium-like strains with the antigenic formula: 1,4,5,12:i:-, , and iii) other serotypes. Along with the sample collection, a questionnaire concerning herd management and potential risk factors was utilised. The data have a “natural” hierarchical structure so a categorical multilevel analysis of the dataset was carried out using a Bayesian hierarchical model. The model was estimated using Markov Chain Monte Carlo methods, implemented in the software WinBUGS.ResultsThe significant associations found (when compared to category “no Salmonella”), for category “serotype Typhimurium or S. Typhimurium-like strains with the antigenic formula: 1,4,5,12:i:-” were: age of breeding sows, size of the herd, number of pigs/pen and source of semen. For the category “other serotypes” the significant associations found were: control of rodents, region of the country, source of semen, breeding sector room and source of feed.ConclusionsThe risk factors significantly associated with Salmonella shedding from the category “serotype Typhimurium or serotype 1,4,5,12:i:-“ were more related to animal factors, whereas those associated with “other serotypes” were more related to environmental factors. Our findings suggest that different control measures could be used to control different Salmonella serotypes in breeding pigs.

Transmission parameters estimated for Salmonella typhimurium in swine using susceptible-infectious-resistant models and a Bayesian approach

BackgroundTransmission models can aid understanding of disease dynamics and are useful in testing the efficiency of control measures. The aim of this study was to formulate an appropriate stochastic Susceptible-Infectious-Resistant/Carrier (SIR) model for Salmonella Typhimurium in pigs and thus estimate the transmission parameters between states.ResultsThe transmission parameters were estimated using data from a longitudinal study of three Danish farrow-to-finish pig herds known to be infected. A Bayesian model framework was proposed, which comprised Binomial components for the transition from susceptible to infectious and from infectious to carrier; and a Poisson component for carrier to infectious. Cohort random effects were incorporated into these models to allow for unobserved cohort-specific variables as well as unobserved sources of transmission, thus enabling a more realistic estimation of the transmission parameters. In the case of the transition from susceptible to infectious, the cohort random effects were also time varying. The number of infectious pigs not detected by the parallel testing was treated as unknown, and the probability of non-detection was estimated using information about the sensitivity and specificity of the bacteriological and serological tests. The estimate of the transmission rate from susceptible to infectious was 0.33 [0.06, 1.52], from infectious to carrier was 0.18 [0.14, 0.23] and from carrier to infectious was 0.01 [0.0001, 0.04]. The estimate for the basic reproduction ration (R0) was 1.91 [0.78, 5.24]. The probability of non-detection was estimated to be 0.18 [0.12, 0.25].ConclusionsThe proposed framework for stochastic SIR models was successfully implemented to estimate transmission rate parameters for Salmonella Typhimurium in swine field data. R0 was 1.91, implying that there was dissemination of the infection within pigs of the same cohort. There was significant temporal-cohort variability, especially at the susceptible to infectious stage. The model adequately fitted the data, allowing for both observed and unobserved sources of uncertainty (cohort effects, diagnostic test sensitivity), so leading to more reliable estimates of transmission parameters.

Relationship between Zoometric Measurements in Holstein-Friesian Cow and Cubicle Size in Dairy Farms

Fueron investigadas las medidas corporales en la raza Holstein-Friesian Portuguesa y su asociacion con las dimensiones de los cubiculos. Durante un periodo de 5 meses, se recogieron las medidas corporales y los datos de tamano de cubiculos de 55 explotaciones lecheras comerciales portuguesas incluyendo un total de 1054 animales. Los datos fueron analizados utilizando el modelo linear general y componentes principales. Las medidas del cuerpo mas relevantes fueron: altura a la cruz (141,1±4,7 cm), altura a la grupa (144,2±4,5 cm), longitud del tronco (170,8±8,3 cm), ancho biisquiatica (55,9±4,2 cm) y el perimetro del torax (206,8±10,4 cm). En general, la primera paridad revelo diferencias (P<0,001), lo que se encuentra asociado con el desarrollo de los animales. La longitud y la ancho del cubiculo cabeza con cabeza fue 223±11 cm y 113±5 cm respectivamente, mientras que en el cubiculo frente a la pared, la longitud fue 227±18 cm y el ancho de 111±7 cm. Las medidas del cuerpo con las mas altas correlaciones se observaron entre las diferentes alturas y entre la altura del pecho y el perimetro del torax. El analisis no evidencio relacion alguna entre las medidas del cuerpo y las dimensiones de los cubiculos. El analisis de componentes principales de las medidas del cuerpo y de las diferentes dimensiones de los cubiculos explican el 51,4% de la variabilidad total, en la que el primer factor representa el 40,2% y el segundo el 11,1%.

Limited Knowledge About Hydatidosis Among Farmers in Northwest Portugal: A Pressing Need for a One Health Approach

Hydatidosis is a re-emerging disease. Farmers are a vulnerable population; however, little is known about their awareness of this disease. The purpose of this study was two-fold: (1) to assess sheep and goat farmers’ awareness of, perceptions of, and attitudes towards parasitic zoonoses and hydatidosis and (2) to identify the preferred means for promotion of information about hydatidosis. A cross-sectional study was conducted. An in-person questionnaire was constructed and administered to 279 individuals. A coprological survey in shepherd dogs was performed using 88 faecal samples. SPSS version 18.0 was used for statistical analysis. Farmers reported several risk practices (69% practice home slaughtering, 46% do not deworm the dogs, 58% of these dogs have contact with other animals) and very little knowledge about hydatidosis (97% have never heard about it). Nevertheless, 75% of the farmers demonstrated interest in receiving information, mainly from a veterinarian. A wide diversity of potentially zoonotic parasites (Trichuris spp., Ancylostomatidae, Toxocara spp., Taeniidae) was found in 61% of the dogs. This survey revealed farmers’ lack of knowledge in relation to hydatidosis and a high prevalence of potentially zoonotic parasites in dogs, thus pointing to the need for health education and a closer collaboration between veterinarian and public health professionals.

Prevalence of antimicrobial resistance in faecal enterococci from vet-visiting pets and assessment of risk factors

The objective of this study was to determine the prevalence of antimicrobial resistance (AMR) exhibited by enterococci isolated from faeces of pets and its underlying risk factors. From September 2009 to May 2012, rectal swabs were collected from 74 dogs and 17 cats, selected from the population of animals visiting the Veterinary Hospital of University of Porto, UPVet, through a systematic random procedure. Animal owners answered a questionnaire about the risk factors that could influence the presence of AMR in faecal enterococci. Enterococci isolation, identification and antimicrobial (AM) susceptibility testing were performed. Data analyses of multilevel, univariable and multivariable generalised linear mixed models were conducted. From all enterococci isolated (n=315), 61 per cent were considered multidrug-resistant, whereas only 9.2 per cent were susceptible to all AMs tested. Highest resistance was found to tetracycline (67.0 per cent), rifampicin (60.3 per cent), azithromycin (58.4 per cent), quinupristin/dalfopristin (54.0 per cent) and erythromycin (53.0 per cent). Previous fluoroquinolone treatments and coprophagic habits were the features more consistently associated with the presence of AMR for three (chloramphenicol, ciprofloxacin and azithromycin) and seven (tetracycline, rifampicin, gentamicin, chloramphenicol, ciprofloxacin, erythromycin and azithromycin), respectively, out of nine AMs assessed. Evaluating risk factors that determine the presence of drug-resistant bacteria in pets, a possible source of resistance determinants to human beings, is crucial for the selection of appropriate treatment guidelines by veterinary practitioners.

Relationship between stepping and kicking behavior and milking management in dairy cattle herds

ABSTRACT We studied the relationship between behavior during milking with milking parlor management, measuring the occurrence of steps and kicks, and cow‐related factors. We also investigated the link between stepping and kicking during milking and udder health. A total of 2,903 direct observations of milking behavior were collected in 44 dairy herds in the north of Portugal. The results showed great variability in the occurrence of stepping and kicking among herds during milking. Mixed linear and logistic regression models for factors associated with stepping and kicking were developed. Cows in tandem milking parlors took fewer steps (P < 0.003) than in herringbone ones, although in the tandem milking system, more kicking occurred than in parallel and herringbone systems. Milking room temperatures of more than 27°C led to a higher frequency of kicks among cows (P < 0.010). The practice of overmilking also produced a significantly greater frequency of cow stepping (P < 0.001). Primiparous cows stepped a third less frequently than did greater parity cows but showed a greater tendency to kick compared with the multiparous ones. Cows with somatic cell counts for more than 200,000 cells/mL at the time of the visit also showed a trend toward higher kicking frequency. The results suggest that animal welfare measures, like kicking and stepping, are suitable for epidemiologic studies. Significant interactions were observed when animals were affected by challenging health and welfare situations.

Association of paratuberculosis sero-status with milk production and somatic cell counts across 5 lactations, using multilevel mixed models, in dairy cows

The aim of this work was to investigate associations between individual cow Mycobacterium avium ssp. paratuberculosis (MAP) seropositivity, 305-d corrected milk production, and somatic cell count during 5 lactations lifespan in Portuguese dairy herds using multilevel mixed models. We used MAP serum ELISA (Idexx MAP Ac, Idexx Laboratories Inc., Westbrook, ME) results (n = 23,960) from all the 20,221 adult cows present in 329 farms and corresponding 47,586 lactation records from the National Dairy Improvement Association. Cows and farms were classified as positive or negative. Multilevel mixed models were used to investigate the association of cow MAP status with variation in milk production and somatic cell count. Cow MAP status, farm status, and lactation number were considered as independent variables. A quadratic function of lactation number was used to mimic the effect of lactation order on milk production. The models considered 3 levels: measurement occasion (level 1) within cow (level 2) and cow within farm (level 3). Four final models were produced, including all herds and cows, to address the effect of farm status (models 1 and 2) or the effect of cow status (models 3 and 4) on the outcome variables. Our results show that MAP status affects milk production. Losses are detectable from third lactation onward. During the first 5 lactations, positive cows accumulated an average loss of 1,284.8 kg of milk when compared with the negative cows. We also observed that somatic cell counts were higher in positive cows and a positive interaction occurs between cow status and lactation number, suggesting a positive association between MAP infection and increased somatic cell counts. Our results are in line with previous studies, suggesting a possible positive relation between cow milk production and susceptibility to MAP infection.

Immunocytochemical study of canine lymphomas and its correlation with exposure to tobacco smoke

Aim: Canine lymphoma is one of the most common canine neoplasms, but little is known regarding the effects of exposure to tobacco smoke on their biologic behavior. As cytology is the most frequent diagnostic method of canine lymphoma, the aims of this study were to perform an immunocytochemical study of canine lymphomas, including subtyping and cell proliferation analysis, and to establish their correlation with tobacco smoke exposure. Materials and Methods: A total of 23 dogs diagnosed with lymphoma were subjected to careful fine-needle biopsies of enlarged lymph nodes. The smears were air-dried, fixed with cold acetone, and immunocytochemically stained using CD3, PAX5, and Ki-67. Owners were requested to complete an epidemiologic questionnaire. Results: According to the updated Kiel classification, 65% were B-cell lymphomas - three low grade (LG) and 12 high grade (HG) and 35% were T-cell -two LG and six HG. Thirteen tumors presented high Ki67 indexes (>40%) (11 HG and 2 LG), two revealed moderate ones (20-40%) (1 HG and 1 LG), and three had low indexes (≤20%) (1 HG and 2 LG). Both a significant positive correlation and a significant linear-by-linear association (p=0.018) were observed between high Ki67 indexes and smoking owners (r=0.753, p=0.002) as well as with the number of smokers in the household (r=0.641, p=0.001). Moreover, the mean percentage of Ki67+ cells from the group of “smoker owners” was statically higher (p=0.011) than that from the “non-smoker owners.” Conclusion: The results suggest that cytological diagnosis of canine lymphomas benefits from being complemented with immunocytochemical studies that include subtyping and assessment of proliferative activity, both contributing for the prognosis and therapeutic planning. Furthermore, exposure to tobacco smoke seems to be related to the biological behavior of canine lymphomas.

A multilevel study of the environmental determinants of swine ascariasis in England

Ascariasis is considered a common parasitosis of swine worldwide. The disease causes significant economic losses due to its effect on feed conversion ratio and liver condemnations at slaughter (liver milk spots). This study aimed to characterise the between-farm and spatial variance in porcine ascariasis in England and to assess the association between the percentage of infected animals and potential environmental risk factors, including production system, socioeconomic deprivation, soil characteristics (pH, topsoil bulk density, topsoil organic matter, topsoil texture class, soil water regime, topsoil available water capacity, and elevation), and climatic conditions (relative humidity, air temperature, and rainfall) before slaughter. Post-mortem inspection results were provided by the Food Standards Agency and comprised information about the number of rejected livers, the number of animals sent to slaughter and the production system. All farms were georeferenced based on the postcode, which allowed the assessment of the area index of socioeconomic deprivation and the extraction of soil and climatic characteristics available in different online databases. Under a multilevel framework with adjustment for spatial autocorrelation, a standard linear mixed model was fitted to estimate the association between these determinants and the percentage of infected animals. From 2,513,973 English farmed pigs included in the study, 4.3% had their livers rejected due to milk spots. The percentage of infected pigs per batch ranged from 0% to 100%. The highest percentages were found in Surrey, East and West Sussex (8.9%) and lowest in Leicestershire, Rutland and Northamptonshire (2.0%). Significant associations were found at multivariable analysis between the proportion of infection and the number of animals sent to slaughter (β=-0.005; 95%CI=-0.005, -0.004), soil texture (peat compared to coarse textured soils; β=-0.516; 95%CI=-1.010, -0.063), relative humidity (β=0.011; 95%CI=0.006, 0.015), mean temperature (β=0.007; 95%CI=0.003, 0.012), and rainfall (β=0.022; 95%CI=0.004, 0.037). In conclusion, our findings suggest that ascariasis can be influenced by a complex network of environmental factors. Future research needs to acknowledge these intermingled relationships to guide the development and application of control measures by the industry.