BVDV control program in Austria - is a monitoring of the BDV status in sheep in Austria necessary?

Abstract

ABSTRACT:In cattle referred to the Clinic of Ruminants at the University of Veterinary Medicine Vienna by local veterinarians from Lower Austria, the number of animals positive for antibodies against pestiviruses decreased from 11.9% in 2004 to 7.4% in 2007. In other Austrian regions the seroprevalence of 17.6% in 2004 dropped to 12.2% in 2007. The seroprevalence rates were considerably higher in older animals than in younger indicating a marked decrease of new infections (8.2% in < 1.5 years old animals, 6.8% in 1.5-4.5 years, 19.8% in 4.5-7.5 years and 33.3% in > 7.5 years). These data nevertheless also demonstrate that new pestivirus infections occur, although at a lower rate. We report the case of a calf persistently infected with Border disease virus-3 (BDV-3) detected in a mixed cattle and sheep farm with the status "BVDV-free". Earlier investigations have shown that BDV-3 is endemic in Austrian sheep populations and seems to be a potential risk factor for the reintroduction of pestiviruses in BVDV free cattle herds. Serological findings among the investigated sheep population showed in four out of nine sheep samples considerably higher titres to the BDV strain Moredun than to the BVDV strain NADL. Seroconversion against pestiviruses was also detected in contact cattle and the mother of the persistently infected calf. Pestivirus specific RNA was neither detected in the blood samples collected from the patients of the Clinic for Ruminants nor in the sheep or cattle investigated on the farm described.

Influence of border disease virus (BDV) on serological surveillance within the bovine virus diarrhea (BVD) eradication program in Switzerland

“…Thus, the mean BDV seroprevalence in pestivirus-antibody positive cattle of at least 6.7% with an increasing trend between 2012 and 2014 indicates that the serological surveillance by ELISA, which does not differentiate BVDV from BDV infections, might be critical. Even though discrimination by cross-SNT as described in this study is laborious, it adds to classical epidemiological investigations and allows the identification of possible sources of infection, which is of particular importance in the late phase of an eradication program [37, 48]. In summary, we determined for the first time the prevalence of BDV in pestivirus-positive cattle in Switzerland, and we provide strong evidence that common housing of cattle and sheep is the most significant risk factor for the interspecies transmission of BD virus from small ruminants to cattle.…”

“…Virus transmission was described between cattle and both, sheep and goats ([19, 43, 44], and references therein). Natural infections of cattle with BDV were reported in England and Wales [45, 46], Austria [47, 48], Italy [49] and New Zealand [50]. Common housing of cattle with persistently infected sheep was the most important cause for seroconversions, and resulted in reduced fertility and abortions in pregnant cows [19, 44, 46].…”

Evidence for Tunisian-Like Pestiviruses Presence in Small Ruminants in Italy Since 2007

“…Traditionally, all pestiviruses isolated from goats and sheep have been referred to as BDV, but genetic characteri-zation has shown that they can be infected with a wide range of pestiviruses including BDV, BVDV-1 and BVDV-2 (Pratelli et al, 2001;Giammarioli et al, 2015b). Equally, cases have reported of calves persistently infected with BDV (Krametter-Froetscher et al, 2009). Furthermore, recent studies showed that BDV strains have a genetic diversity greater than other pestivirus species (Giammarioli et al, 2011).…”

“…In contrast to what is observed in CSFV infections, ruminant pestiviruses show low species specificity in serological tests (Vilcek et al., ; Krametter‐Froetscher et al., ). In fact, BVDV‐1, BVDV‐2 and BDV are frequently detected either in cattle, sheep, goats and pigs.…”

Global Distribution and Genetic Heterogeneity of Border Disease Virus

“…Several epidemiological studies have shown that BDV genotypes can affect a wide range of ungulates, but generally, sheep seem naturally sensitive to pestivirus infection. BDV infection is globally distributed and was reported in different European countries such as Austria [ 30 , 32 , 36 , 46 , 79 , 80 ], France [ 4 , 5 , 14 , 41 , 81 ], Germany [ 12 , 39 , 44 , 82 , 83 ], Italy [ 15 , 16 , 31 , 66 , 76 , 77 , 78 , 79 ], the Netherlands [ 24 , 28 , 84 ], Slovakia [ 85 ], Spain [ 1 , 6 , 7 , 9 , 13 , 27 , 48 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 ], Switzerland [ 35 , 51 , 92 , 96 , 97 , 98 , 99 ], and the United Kingdom [ 3 , …”