Effects of bivalent bluetongue virus serotypes 2 and 9 vaccine on reproductive performance of cattle: a case study in Calabria, Italy.
Following the occurrence of bluetongue (BT) in Italy in the summer and autumn of 2000, the Italian Ministry of Health decreed (in May 2001) that all sheep, goats and cattle in infected, and in neighbouring areas, be vaccinated. The principal aim of the vaccination campaign was to create a resistant animal population, thereby reducing overall virus circulation. Accordingly, during 2002, the live-attenuated bivalent vaccine against BT virus (BTV) serotypes 2 and 9, produced by Onderstepoort Biological Products in South Africa, was administered in Calabria. A large herd of cattle (over 900 animals, including 390 cows) was monitored for four months after vaccination to establish whether any abnormalities (such as stillbirth and placental retention) occurred during parturition. During the study, 111 cows (89 vaccinated and 22 unvaccinated) gave birth; in 26 cows, abnormalities were observed but no association was found to occur between the vaccination of cows against BT and the birthing abnormalities observed (Pearson's chi-square=0.517, P>0.05). The animals were divided into four groups according to the number of days between vaccination and parturition (less or equal to 31 days, 31-60 days, 61-90 days, more than 90 days); again no link was found between vaccination and the abnormalities observed.
Lucifora
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Istituto Zooprofilattico Sperimentale del Mezzogiorno, Sezione Diagnostica di Cosenza, Via Panebianco 301, 87100 Cosenza, Italy.
Rossi
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P
Calistri
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P
Giovannini
A
A