Natural Changes in the Spread of Bovine Viral Diarrhoea Virus (BVDV) Among Estonian Cattle

Abstract

The results of a survey conducted during 1993-2000 to study the spread of bovine viral diarrhoeal virus (BVDV) among Estonian cattle are presented. The BVDV infection status of a representative random sample of cattle herds housing 20 or more dairy cows was established to estimate the prevalence of herds with active BVDV infection [potentially having persistently infected (PI) cattle--suspect PI herds]. The herds investigated comprised approximately 70% of all Estonian dairy cows. The BVDV infection status was established in 315-350 herds (making the sampling fraction about 20%) during three sampling periods: 1993-95, 1997-98, 1999-2000. BVDV antibodies were detected in herd bulk milk samples and/or sera from young stock by a liquid-phase-blocking enzyme-linked immunosorbent assay developed in the Danish Veterinary Institute for Virus Research. The results of the survey demonstrate the reduction in the prevalence of herds with active BVDV infection in the studied fraction of the Estonian cattle population. During the first sampling period (1993-95) a prevalence of 46% (+/- 5%) for suspect PI herds was observed, during the second sampling period this prevalence was 16% (+/- 3%) and in the third period it was 18% (+/- 3%). As there is no control programme for BVDV in Estonia, the observed changes reflect the natural course of the infection in the study population. A possible cause for these changes is the decreased trade in breeding animals as a result of the economic difficulties present in cattle farming during the study period. The farming practices (most large herds are managed as closed herds) and the low density of cattle farms have obviously facilitated the self-clearance of herds from the BVDV infection, diminishing the new introduction of infection into the herds.

Prevalence and risk factors associated with bovine viral diarrhea virus infection in dairy herds in Jordan

“…In Canada, the number of cases submitted to the diagnostic laboratories reflected those geographic areas with the highest cattle density (Alves et al 1996). A reduction in the prevalence of herds with active BVDV infection was observed in closely confined herds and in areas where cattle population density was low (Viltro et al 2002). In this study, there was no significant difference in BVDV seroprevalence in different age groups although the percentage of BVDV seropositive cows increased as animals became older than 6 year of age.…”

Detection of antibodies to bovine viral diarrhea virus in cattle presented for slaughter at Sokoto metropolitan abattoir, Nigeria

“…The results are also similar with the findings of Falcone et al (2001) who reported a seroprevalence rate of 62% in parts of Italy (Lombardia and Emilia Romagna). The research findings, on the other hand, were slightly different from the results of the study in Estonian cattle by Viltrop et al (2002). They observed a prevalence of herds potentially having PI animals of 46, 16 and 18% for three consecutive time periods.…”

“…Vertical transmission plays an important role in the epidemiology and pathogenesis of the disease (Bolin, 1995). Despite the various works carried out so far on the prevalence of this virus in various parts of Nigeria and Cameroons (Okeke et al, 1977;Baba et al, 1994;Handel et al, 2011) and the world at large (Paton et al, 1998;Ferreira et al, 2000;Falcone et al, 2001;Viltrop et al, 2002), there is still no research done to investigate and evaluate the prevalence of this virus among cattle in Sokoto, Nigeria.…”

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

“…Results from previous publications demonstrate that the proportion of herds potentially having active BVDV infection shows a wide range of variation between countries and between regions within countries [6,26,23,12,20,30,35]. This variation may in part be explained by differences in demography, such as herd size and population density, and management factors such as the pattern and frequency of animal movements [13].…”