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Bovine viral diarrhoea virus (BVDV) is an economically important pathogen of cattle worldwide. Infection of a pregnant animal may lead to persistent infection of the foetus and birth of a persistently infected (PI) calf that sheds the virus throughout its life. However, BVD viruses are not strictly species specific. BVDV has been isolated from many domesticated and wild ruminants. This is of practical importance as virus reservoirs in non-bovine hosts may hamper BVDV control in cattle. A goat given as a social companion to a BVDV PI calf gave birth to a PI goat kid. In order to test if goat to goat infections were possible, seronegative pregnant goats were exposed to the PI goat. In parallel, seronegative pregnant goats were kept together with the PI calf. Only the goat to goat transmission resulted in the birth of a next generation of BVDV PI kids whereas all goats kept together with the PI calf aborted. To our knowledge, this is the first report which shows that a PI goat cannot only transmit BVD virus to other goats but that such transmission may indeed lead to the birth of a second generation of PI goats. Genetic analyses indicated that establishment in the new host species may be associated with step-wise adaptations in the viral genome. Thus, goats have the potential to be a reservoir for BVDV. However, the PI goats showed growth retardation and anaemia and their survival under natural conditions remains questionable.

A national eradication programme was designed with the aim of achieving total freedom from bovine viral diarrhea virus (BVDV) infection in the Swiss cattle population. The eradication programme consisted of testing every Swiss bovine for antigen, culling virus-positive animals and applying movement restrictions. Starting in 2008, the campaign achieved the goal of reducing the proportion of newborn calves that were virus-positive from 1.8% to under 0.2% within two years (situation in September 2010). Both good data flow between the parties involved as well as speed and efficiency (e.g. concerning the application of tests, movement restrictions and slaughter) are central to the success of the programme. Since the beginning of the programme 2.85 million cattle have been tested for bovine viral diarrhea virus (BVDV). The BVD-prevalence in cattle at the individual and herd levels following the implementation of the eradication programme was assessed. Using data collected during this campaign a risk factor analysis was conducted in order to identify factors associated with the appearance of virus positive newborn calves in herds where BVD had not previously been detected; these risk factors would allow targeting of future surveillance. Herd size, early death rate (i.e. the number of animals that either die before 15 days of age or are stillborn per number of newborns per year), buying in stock, using communal summer grazing, production type, age structure and management strategy were factors associated with the appearance of new cases of infection. Testing of newborn calves for antigen will continue to be conducted until the end of 2011, this is combined with outbreak investigation of newly infected herds (consisting of re-testing dams of virus-positive calves and if necessary all cattle on or that recently left the farm). This process is done to identify infected animals that may have been missed during prior testing (false negatives), it also serves to identify other factors that may be responsible for the introduction of BVDV onto the farm. Since October 2009, testing of calves for antigen combined with outbreak investigation has led to the detection of 55 infected animals that had tested negative (presumably false negative) during previous rounds of testing., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The Swiss BVD eradication campaign aims at eliminating the disease from the cattle population within a few years. During the initial phase from October 1st to December 31th 2008, all bovines will be individually tested and those found virus-positive slaughtered. In the following secondary phase, all newborn calves will be tested using ear notches taken on the occasion of the regular tagging process. From 2011 onwards, freedom of disease shall be confirmed based on a routine monitoring program, starting with antibody detection in milk of first lactating cows. In order to reduce the number of new infections, all bovines "not yet calved" and destined for shared mountain pastures were pretested in spring 2008. The more than enthusiastic start led to an extension of testing far beyond the targeted segment, resulting in almost 600'000 or more than one third of the population being tested until the end of June, 1.1% of which with a positive result. This overwhelming kick-off was extremely demanding for all parties involved, but also allowed identifying many limiting steps that could be optimized in view of the initial phase.

An ELISA for the detection of antibodies to bovine viral diarrhea virus (BVDV) was developed based on antigens derived from a genotype I BVDV strain isolated in Switzerland. Using monoclonal antibodies we showed that this antigen contained the conserved non-structural protein NS3 whereas it essentially lacked the more strain-specific E2 surface glycoprotein. This ELISA has a sensitivity of 97.5% and a specificity of 99.2% as compared to the serum neutralization test (SNT). Preliminary experiments showed that this ELISA reliably detects antibodies to BVDV strains circulating in Brazil. Serum samples obtained from 430 adult cattle on 19 farms of the State of Rio Grande do Sul (Brazil) and one farm from Corrientes (Argentina) were tested for antibodies by means of this ELISA. We found antibodies in 56% +/- 15.1% of the cattle sera tested, which indicates that, in Brazil, the prevalence of infection with BVDV is similar to that found in Europe and the USA. Our sequence analysis of two BVDV isolates showed that BVDV of both genotypes I and II circulate in Brazil.

The goal of this study was to determine the influence of communal pasturing on the spread of bovine virus diarrhoea (BVD). The investigation involved 990 Swiss Braunvieh cattle from 149 different owners on seven communal pastures in the Swiss Alps. Prior to pasturing, blood samples were collected from all animals for examination for BVD antigen and antibodies. Serological examinations were also performed during and after pasturing to determine possible increases in seroprevalence and to determine whether seroprevalence was different on pastures with and without persistently infected cattle. At the start of pasturing, nine (0.9%) animals were persistently viraemic. On three alpine pastures, no persistently viraemic animals were detected. The prevalence of persistently infected cattle on the remaining four pastures varied from 0.3 to 3.9%. Of the 990 animals tested at the start of pasturing, 632 (63.3%) were seropositive. Seroprevalence differed among pastures and varied from 21.8 to 85.9%. During the summer, seroprevalence increased on all pastures surveyed, and at the end of the pasture season, 778 (80.1%) of the 971 cattle that were examined twice were seropositive. The incidence of seroconversion was significantly higher on pastures with persistently infected cattle compared with those without; it ranged from 32.7 to 100.0% in the former and from 6.0 to 22.2 in the latter. The results of this study suggest that communal alpine pasturing does play a role in the spread of BVD. The extent of this role depends on the presence of persistently infected animals.