Severe malformations in calves associated with bovine viral diarrhoea (BVD) virus infection in a dairy cattle herd

Virus as Teratogenic Agents

Viral infectious diseases are important causes of reproductive disorders, as abortion, fetal mummification, embryonic mortality, stillbirth, and congenital abnormalities in animals and in humans. In this chapter, we provide an overview of some virus, as important agents in teratology.We begin by describing the Zika virus, whose infection in humans had a very significant impact in recent years and has been associated with major health problems worldwide. This virus is a teratogenic agent in humans and has been classified as a public health emergency of international concern (PHEIC).Then, some viruses associated with reproductive abnormalities on animals, which have a significant economic impact on livestock, are described, as bovine herpesvirus, bovine viral diarrhea virus, Schmallenberg virus, Akabane virus, and Aino virus.For all viruses mentioned in this chapter, the teratogenic effects and the congenital malformations associated with fetus and newborn are described, according to the most recent scientific publications.

Seroprevalence and association of bovine viral diarrhea virus (BVDV) serostatus with reproductive problems in dairy cattle in central and southern Ethiopia

Bovine viral diarrhea (BVD) is an economically important cattle disease with worldwide distribution and characterized mainly by suboptimal fertility in the affected herds. The objectives of this study were to estimate the seroprevalence of BVDV within dairy cattle, to identify potential risk factors, and to assess the association with occurrence of reproductive problems. Sera (n = 954) collected from dairy cattle from 98 herds in southern and central Ethiopia were tested for BVDV antibodies using a commercial ELISA. Among screened sera samples, 20.9% (95% CI, 18.4, 23.6) tested positive to BVDV antibodies. The herd prevalence was 50% (95% CI, 40.1, 59.9) and the intra-herd prevalence ranged between 2.6 and 100% (mean = 31.4%) in positive herds. Geographic region, herd size, and animal arrangement in the farm had significant association with serostatus (p < 0.05). Cattle from southern Ethiopia and herds of large size had 2.8 (95% CI, 1.9, 4.2) and 2.6 (95% CI, 1.5, 4.6) times higher odds of being seropositive compared to their counterparts, respectively. Serostatus to BVDV was associated with history of anestrus, repeat breeding (RB), mastitis, and extended calving interval (CI) (p < 0.05). Animals with history of extended CI and mastitis were 1.7 (95% CI, 1.0, 2.7) and 2.2 (95% CI, 1.5, 3.2) times more likely to be seropositive compared with those with normal CI and no history of mastitis, respectively. On the other hand, animals with history of anestrus and RB were less likely to be seropositive to BVDV compared to cattle with no such history. Sera from 26 selected cattle were also examined using reverse transcription (RT)-PCR for detection of BVDV RNA; however, all samples tested were negative for the presence of BVDV nucleic acid. Our study highlights the variation in BVDV status within Ethiopian dairy herds, and association with some important reproductive performance traits and potential risk factors.

Serological evidence of Bovine herpesvirus-1, Bovine Viral Diarrhea virus and Schmallenberg virus infections in relation to reproductive disorders in dairy cattle in Ethiopia

Reproductive disorders in dairy cattle have been noted to be common in urban and peri-urban dairy production system in Ethiopia. The available reports on the causes of these disorders, however, are not conclusive. A case-control study was designed to investigate the possible association of major reproductive disorders in dairy cattle with exposure status to bovine herpesvirus-1 (BHV-1), bovine viral diarrhea virus (BVDV) and Schmallenberg virus (SBV). Cows with history of abortion/stillbirth were considered as cases (n=204) while, those cows with no such history were taken as control (n=359). The serological screening tests used for all the three viruses were blocking enzyme linked immunosorbent assays (B-ELISAs). Of the total 563 samples tested 58.4%, 43.8% and 32.9% were positive for SBV, BHV-1 and BVDV, respectively. Significant difference between cases and controls were noted for SBV (p=0.026) and BHV-1 exposures (p<0.001). The difference noted for BVDV serostatus was not significant (p>0.05). The highest proportion (28.9%) of concurrent exposures was noted for BHV-1 and SBV, followed by SBV and BVDV (21.5%) and BHV-1 and BVDV (20.2%). Evidence of exposures to all the three viruses were detected in 14.4% of the animals. However, significant difference between cases (39.7%) and controls (22.9%) among cattle with multiple sero-positivity was noted only for BHV-1 and SBV (p<0.001). Proportion of uterine infection (p=0.002) and fetal membrane retention (p=0.005) increased in BHV-1 seropositive animals, while repeat breeding was common (p=0.034) among BVDV exposed ones. Seropositive animals to any of the three viruses were detected in all sampled areas and the proportion of cattle with BHV-1 and SBV exposure history had a higher risk to at least one type of the reproductive disorders mentioned compared to the corresponding sero-negative groups.

Seroprevalence and risk factors associated with bovine viral diarrhea virus (BVDV) infection in non-vaccinated dairy and dual purpose cattle herds in Ecuador

A cross-sectional study was carried out to determine the seroprevalence and risk factors associated with Bovine viral diarrhea virus (BVDV) infection in non-vaccinated dairy and dual-purpose cattle herds from Ecuador. A total of 2,367 serum samples from 346 herds were collected from June 2008 through February 2009. A questionnaire, which included variables related to cattle, health, management measures, and the environment, was filled out in each herd. A commercial indirect enzyme-linked immunosorbent assay test was used to determine the seropositivity. A logistic regression model was used to determine risk factors at herd level. The individual seroprevalence for BVDV in non-vaccinated herds in Ecuador was 36.2% (857/2,367; CI(95%), 34.3-38.1%). The herd prevalence was 74% (256/346; CI(95%), 69.4-78.6%) and the intra-herd prevalence ranged between 11.1% and 100% (mean = 51.6%). The logistic regression model showed that the density of cattle farms in the area (more than 70%; OR, 1.94; CI(95%), 1.21-3.2) and the altitude (higher than 2,338 m above sea level; 2.33; CI(95%), 1.4-3.9) are potential risk factors associated with BVDV infection.