Comparison of a novel rapid sampling method to serum and tonsil scraping to detect PRRSV in acutely infected sows.

Few practical methods are available to monitor the PRRSV status of the sows. Common sampling methods for sows like serum sampling, and tonsil scraping involve restraining individual sows and are labor-intensive, time-consuming, relatively invasive, and therefore, have limited use in large-scale production settings. Thus, a practical and rapid method of sampling large numbers of sows is needed. This study aimed to develop a new sampling method, named tonsil-oral scraping (TOSc) and compare TOSc to serum and tonsil scraping in terms of PRRSV qPCR detection rate and Ct values in thirty matched sows, thirty days after PRRSV outbreak. TOSc recovered a mixture of oral fluids and tonsil exudates from the sow oral cavity within seconds without restraining the animals. Results showed that, numerically, the TOSc samples had higher PRRSV qPCR detection rate (100 %) compared to serum (16.8 %) and tonsil scraping (73.1 %). Moreover, TOSc samples had lower average Ct values (29.7) than tonsil scraping (30.7) and serum (35.2). There was no significant difference in the detection rate between TOSc and tonsil scraping (Tukey test, p = 0.992), while there was a significant difference between serum and tonsil scraping (Tukey test, p < 0.001), as well as between serum and TOSc (Tukey test, p < 0.001). In terms of Ct values, there was no statistically significant difference between TOSc and tonsil scrapings (Dunn Test, p > 0.05), while there was a significant difference between tonsil scraping with serum (Dunn Test, p < 0.01), and TOSc with serum (Dunn Test, p < 0.01). Our results suggest great potential of the TOSc as a novel, practical, and rapid tool for PRRSV RNA detection in sows to assess sow herd status.

Longitudinal piglet sampling in commercial sow farms highlights the challenge of PRRSV detection.

BACKGROUND: Processing fluids (PF) and family oral fluids (FOF) are population-based surveillance samples collected from 2- to 5-day-old piglets and due-to-wean piglets, respectively. Although they are described for the surveillance of PRRSV in sows and piglet populations at processing and weaning, there is limited information on their use in commercial herds. This observational study described PRRSV RNA detection over time in PF, FOF, and piglet serum collected from farrowing groups in commercial breeding farms with the objective of achieving robust, practical, and effective PRRSV surveillance protocols. Weekly PF (an aggregate sample of all litters processed in a week from each room), and FOF (a convenience sample attempted from at least 20 individual litters in at least one farrowing room each week) samples were collected from six PRRSV-endemic commercial breeding herds for up to 38 weeks. A total of 561 PF room samples, 2400 individual litter FOF samples, and 600 serum samples (120 pools of 5 samples) were collected during the study period and tested for PRRSV RNA. Data were evaluated for patterns of PRRSV RNA detection by specimen within farms over time. RESULTS: In particular, the detection of PRRSV was commonly sporadic over time within farms (weeks of PRRSV RNA negative results followed by one or more weeks of positive results); was often non-uniform within farms (negative and positive farrowing rooms at a given point in time); and PF and FOF testing results agreement was 75 and 80% at week and room level, respectively, demonstrating that both sampling methods could complement each other. Non-uniformity in PRRSV detection in rooms sampled within the same week and detection after ≥11 consecutive weeks of PRRSV negative PF and FOF results underline the challenge of consistently detecting the virus. CONCLUSIONS: These results suggest that monitoring protocols for breeding herds attempting PRRSV control or elimination can use both PF and FOF to improve PRRSV detection in suckling pig populations.

Description of risk factors associated with the detection of BVDV antibodies in Brazilian pig herds.

Bovine viral diarrhea virus (BVDV) infects ruminants as primary hosts. However, other animals like pigs are susceptible. This study was conducted to investigate seroprevalence and risk factors associated with the detection of BVDV antibodies in pig herds. A total of 1.705 serum samples of 33 finisher herds, from seven Brazilian states, were collected in slaughterhouses. The samples were tested by virus neutralization (VN) test. In total, 5.35% (91/1.705) were positive and 64% (21/33) of the herds had positive animals. A significant association with "trucks are not cleaned and disinfected" and "visitors do not respect 72-h interval between visits to farms" (P < 0.05) was found in association with detection of BVDV-2 antibodies. This study suggests that important biosecurity gaps are present in Brazilian pig farms, as the presence of BVDV antibodies in pigs suggests (direct or indirect) contact with population(s) of ruminant species. Closing biosecurity gaps prevents spread of BVDV and other pathogens such as foot-and-mouth disease virus (FMDV) between pig and ruminant farms. This data should be taken in account by CSF surveillance programs, once cross-reaction in serologic tests between classical swine fever virus (CSFV) and BVDV antibodies has been shown to occur.

Obtenção de isolados puros de Babesia bovis e Babesia bigemina a partir de larvas e ninfas de Boophilus microplus em bezerros neonatos privados de colostro / Pure isolates of Babesia bigemina and Babesia bovis obtained from Boophilus microplus larvae and nymphs in colostrum- deprived newborn calves

O presente trabalho foi desenvolvido com o objetivo principal de obter isolados puros autóctones de B. bovis e de B. bigemina a partir do carrapato Boophilus microplus, naturalmente infectado, assegurando, dessa forma, amostras de referência regional para futuros estudos sobre o tema. Os isolados puros de B. bovis e B. bigemina foram obtidos, respectivamente, através da infestação de bezerros neonatos privados de colostro com larvas e ninfas de B. microplus, naturalmente infectadas. A condição de isolados puros foi comprovada pela soroconversão específica pela reação de imunofluorescência indireta (RIFI), assim como pela reação em cadeia da polimerase (PCR) e subinoculação. Os resultados confirmaram a eficácia da estratégia, anteriormente reportada, para isolamento puro de B. bovis e B. bigemina a partir de larvas e ninfas de carrapatos com infecções naturais. Concluiu-se ainda que o uso de bezerros neonatos privados de colostro, como animais suscetíveis, pode ser considerado um modelo prático, eficaz e relativamente econômico para o isolamento de hemoparasitos em regiões endêmicas.

Detecção de anticorpos contra o vírus da diarréia viral bovina em fêmeas de rebanhos leiteiros não vacinados, com histórico de problemas reprodutivos, nos Estado de Goiás / Bovine viral diarrhea virus: antibody detection in bovine females, not vaccinated, with reproductive disorders of dairy herds, in the State of Goias, Brazil

Este trabalho foi realizado objetivando identificar anticorpos contra o vírus da diarréia viral bovina (BVDV) em fêmeas bovinas não vacinadas de rebanhos leiteiros, com histórico de problemas reprodutivos, em 10 municípios do Estado de Goiás. Foram colhidas amostras pareadas de soro sanguíneo de 452 animais com idade superior a 24 meses e pertencentes a 37 rebanhos desses municípios. A pesquisa de anticorpos foi realizada por meio de um ensaio imunoenzimático (EIE) comercial e da reação de sroneutralização (SN). A análise das primeiras colheitas por EIE demonstrou soropositividade em 35,6 por cento das amostras, enquanto pela SN a positividade encontrada foi 33,2 por cento. O índice Kappa calculado para a comparação dos dois testes foi de 0,84. Foi observada soroconversão em 8,1 por cento das amostras. Do total de prpriedades, 70,3 por cento apresentaram pelo menos um animal sorologicamente positivo, e 80 por cento dos municípios possíam rebanhos infectados.