Detection of Multiple Lineages of PRRSV in Breeding and Growing Swine Farms.

The detection and co-circulation of multiple variants of porcine reproductive and respiratory syndrome virus (PRRSV) have been observed and reported in swine. However, the potential long-term impact of multiple prevailing PRRSV variants on pig-performance is not yet fully understood. The primary objective of this study was to describe the genetic variation of PRRSV in processing fluid (PF), oral fluid (OF), and tonsil scraping (TS) specimens from five swine farms with different production types and PRRS status over a period of time (~1 year). Furthermore, the association between PRRSV prevalence and production parameters was investigated. Results showed that PRRSV was detected by RT-qPCR in 21-25% of all types of specimens. In breeding farms, PRRSV detection in PF and/or TS samples was correlated with stillborn and mummified fetuses, and pre-weaning mortality throughout the study period. Although ORF5 sequences were obtained in <16% of all sample types, simultaneous detection of PRRSV variants including field and vaccine strains within a single sampling event was identified in both breeding and growing pig farms. Phylogenetic analyses based on the ORF5 sequence classified the detected field PRRSV into L1A and L1H, two sub-lineages of lineage 1 (L1). Our study demonstrated the presence of multiple PRRSV lineages, sub-lineages, and variants in swine herds and its potential association with swine reproductive performance under field conditions.

A longitudinal study on PRRSV detection in swine herds with different demographics and PRRSV management strategies.

Porcine reproductive and respiratory syndrome virus (PRRSV) has been one of the major health-related concerns in the swine production industry. Through its rapid transmission and mutation, the simultaneous circulation of multiple PRRSV strains can be a challenge in PRRSV diagnostic, control and surveillance. The objective of this longitudinal study was to describe the temporal detection of PRRSV in swine farms with different production types and PRRS management strategies. Tonsil scraping (n = 344) samples were collected from three breeding and two growing herds for approximately one year. In addition, processing fluids (n = 216) were obtained from piglet processing batches within the three breeding farms while pen-based oral fluids (n = 125) were collected in the two growing pig farms. Viral RNA extraction and reverse-transcription quantitative PCR (RT-qPCR) were conducted for all samples. The sample positivity threshold was set at quantification cycle (Cq) of ≤ 37. Statistical analyses were performed using generalized linear modelling and post hoc pairwise comparisons with Bonferroni adjustments using R statistical software. The results suggested a higher probability of detection in processing fluids compared to tonsil scraping specimens [odds ratio (OR) = 3.86; p = .096] in breeding farms whereas oral fluids were outperformed by tonsil scrapings (OR = 0.26; p < .01) in growing pig farms. The results described herein may lead to an improvement in PRRSV diagnostic and surveillance by selecting proper specimens.

Longitudinal study of influenza A virus circulation in a nursery swine barn.

Commercial production of swine often involves raising animals in large groups through the use of multi-stage production systems. In such systems, pigs can experience different degrees of contact with animals of the same or different ages. Population size and degree of contact can greatly influence transmission of endemic pathogens, including influenza A virus (IAV). IAV can display high genetic variability, which can further complicate population-level patterns. Yet, the IAV transmission in large multi-site swine production systems has not been well studied. The objectives of this study were to describe the IAV circulation in a multi-source nursery facility and identify factors associated with infection in nursery pigs. Pigs from five sow herds were mixed in one all-in/all-out nursery barn, with 81 and 75 pigs included in two longitudinal studies. Virus isolation was performed in Madin-Darby canine kidney cells and serology was performed using hemagglutination inhibition assays. Risk factor analysis for virological positivity was conducted using logistic regression and stratified Cox's regression for recurrent events. In Study 1, at ≈30 days post-weaning, 100% of pigs were positive, with 43.2% of pigs being positive recurrently over the entire study period. In study 2, 48% of pigs were positive at the peak of the outbreak, and 10.7% were positive recurrently over the entire study period. The results suggest that IAV can circulate during the nursery phase in an endemic pattern and that the likelihood of recurrent infections was associated in a non-linear way with the level of heterologous (within-subtype) maternal immunity (p < 0.05). High within-pen intracluster correlation coefficients (> 0.75) were also observed for the majority of sampling times suggesting that pen-level factors played a role in infection dynamics in this study.

Fatores ambientais e antropométricos associados à hipertensão arterial infantil / Environmental and anthropometric factors associated with infantile arterial hypertension

A obesidade infantil, considerada uma pandemia, apresenta custos sócio-econômicos significativos por sua elevada morbimortalidade. Para avaliar a associação entre fatores biológicos e ambientais e a presença de hipertensão arterial (HA), realizou-se estudo transversal com 701 crianças, de 5 a 9 anos, de Feira de Santana, BA. A pressão arterial foi mensurada conforme parâmetros do Update on the 1987 Task Force Report on High Blood Pressure in Children and Adolescents. Definiu-se sobrepeso e obesidade como índice de massa corpórea > aos percentis 85 e 95 para idade e sexo, respectivamente. A análise de entrevistas com os responsáveis possibilitou estudo das variáveis sexo, etnia, idade, história familiar para HA e escola freqüentada. Observados como fatores preditivos independentes para HA a presença de sobrepeso (OR= 4,49; ro= 0,04), obesidade (OR= 13,05; ro= 0,000) e o fato de estudar em escola privada (OR= 1,93; ro= 0,13), sugerindo um papel importante de fatores biológicos e ambientais na gênese da HA em crianças.

[Environmental and anthropometric factors associated with childhood arterial hypertension]. / Fatores ambientais e antropométricos associados à hipertensão arterial infantil.

Childhood obesity is considered pandemic with significant social and economical costs because of its high morbidity and mortality. To evaluate the association between biological and environmental factors and infantile arterial hypertension (AH), a cross-sectional study was performed with 701 children, ranging from 5 to 9 years old, from Feira de Santana, BA. The arterial pressure was measured following the criteria of the Update on the 1987 Task Force Report on High Blood Pressure in Children and Adolescents. Overweight and obesity were defined as body-mass index equal or above the 85th and the 95th percentiles for age and gender, respectively. Interviews with the children's responsible were used to determine the role of gender, ethnic group, age, familiar history of AH, and type of school. Overweight (OR= 4.49; rho= 0.04), obesity (OR= 13.05; rho= 0.000) and studying at private school (OR= 1.93; r= 0.13) were observed as predictive and independent factors associated with hypertension. Therefore, biological and environmental factors seem to be involved on the genesis of AH in children.