BVDV and BHV-1 Infections in Dairy Herds in Northern and Northeastern Thailand

Bulk milk samples from 220 dairy herds were collected at 9 public milk collection centres in the northeastern and northern Thailand, and a subset of 11 herds was selected for individual testing. The samples were tested for presence of antibodies to BVDV and BHV-1 using an indirect ELISA. The results from the bulk milk testing demonstrated a moderate level of exposure to BVDV and BHV-1 (73% and 67%, respectively). However, the low proportion of herds with high BVDV antibody-levels (13%) and the low within-herd seroprevalence of BVDV and BHV-1 in the 11 herds (24% and 5%, respectively), particularly among the young stock (15% and 0%, respectively), demonstrated a low prevalence of active BVDV infection and a low rate of reactivation of latent BHV-1. The presence of a self-clearance process was also indicated by the results from the individual testing. Moreover, a surprisingly low prevalence of BVDV and BHV-1 antibody-positive herds at one of the milk centres was found. This centre was established 5–10 years before the others. Our impression is that this reflects the self-clearance process, where consecutive replacement of imported infected animals without further spread has resulted in a nearly total elimination of the infections. Based on our experiences and on these results we are convinced that this process can continue if there is awareness of herd biosecurity. This is especially important in the context of a future intensification of the dairy production

Reação de imunofluorescência indireta para detecção de anticorpos anti-Neospora caninum em amostras coletivas de leite Indirect fluorescent antibody test to detection of Neospora caninum antibodies in samples of bulk milk

O objetivo deste estudo foi determinar a presença de anticorpos anti-Neospora caninum em amostras coletivas de leite, através da reação de imunofluorescência indireta (RIFI). Para isso, foram coletadas amostras do leite dos tanques refrigerados de 36 rebanhos, das quais foram selecionadas 14 para coletas de amostras individuais de soro sanguíneo e de leite das vacas. Encontrou-se correlação em 12 dos 14 rebanhos selecionados para a amostragem individual dos animais, em comparação à detecção de anticorpos nas amostras coletivas de leite. Foi observada uma concordância de 76% comparando-se o resultado das amostras coletivas com os resultados individuais de leite. Observaram-se baixos títulos de anticorpos (50) no soro sanguíneo dos animais soropositivos, cujos resultados da RIFI no leite coletivo e no sangue foram discordantes. Assim, a partir dos resultados deste estudo, pode-se concluir que a utilização de testes sorológicos para detecção de anticorpos anti-N. caninum em amostras coletivas de leite através da RIFI pode ser uma opção ao diagnóstico para a triagem de rebanhos positivos bem como para estudos epidemiológicos.<br>The aim of this study was to determine the presence of anti-N. caninum in the bulk milk samples by indirect immunofluorescence assay (IFAT). For this, it was collected samples of milk from refrigerated tanks from 36 herds, of which 14 were selected for sampling of individual blood serum and milk of cows. It was found concordance for 12 of the 14 herds selected for samples of individual animals, compared to the detection of antibodies in the bulk milk samples. Concordance was of 76% when comparing the results of the pooled sample with the results of individual milk. It was observed low antibody titers (50) in the serum of animals positive whose results in IFA of bulk milk and blood were discordant. Thus, with the results of this study, it can be concluded that the use of serological tests for detection of anti-N. caninum in the bulk milk samples from the IFAT could be an alternative diagnosis for the screening of positive herds as well as for epidemiological studies