Microscopic view of virus particles around a bull in a laboratory.

Schmallenberg Virus: What Farmers Need to Know About Semen Contamination

Mira Elwood in Health & Wellness June 2025 • 4 min read.

"New research sheds light on the detection and potential risks of Schmallenberg virus (SBV) in bovine semen, providing crucial insights for livestock management."

In 2011 and 2012, Europe faced a new challenge: the emergence of the Schmallenberg virus (SBV), an arbovirus affecting domesticated ruminants. SBV can cause mild illness in adult cattle, reducing milk production and causing fever and diarrhea. The real concern arises in pregnant animals, where SBV is linked to abortions and birth defects in lambs and calves.

Since its initial detection in Germany, SBV spread rapidly across Europe, impacting thousands of farms. Economic losses have been substantial, particularly in sheep farms where a significant percentage of ewes experienced abnormal births or stillbirths.

Recent research has focused on understanding how SBV is transmitted and how it affects cattle. A key area of investigation is the presence and viability of SBV in bovine semen. A study published in Epidemiology and Infection explored SBV excretion in bovine semen after experimental infection, providing valuable insights for managing the risks associated with this virus.

Key Findings: SBV Detection in Bovine Semen

Microscopic view of virus particles around a bull in a laboratory.

A study was conducted where two bulls were experimentally infected with SBV to monitor the virus's presence in their semen. Semen samples were collected daily for three weeks and tested using qRT-PCR to detect SBV RNA.

The research revealed that SBV RNA could indeed be detected in the semen of infected bulls. The highest concentrations were found during the first week after infection (days 4-7). However, the concentrations were relatively low (Ct values 30–39).

Viremia and Symptoms: Both bulls developed viremia (presence of the virus in the blood) accompanied by fever and diarrhea.
Limited Virus Isolation: Viable SBV was only isolated from blood samples, not from semen or genital tissues.
Lymph Node Detection: At 24 days post-infection, SBV RNA was detected in the mesenteric and inguinal lymph nodes, which drain the genital tissues.

These findings suggest that while SBV RNA can be present in semen, the amount is low, and the virus might not be viable. This raises questions about the potential for transmission through artificial insemination.

Implications and Future Research

This research contributes to our understanding of SBV and its potential routes of transmission. The detection of SBV RNA in semen, even at low concentrations, raises concerns about the safety of artificial insemination practices.

While the study found SBV RNA in semen, it did not confirm whether the virus was infectious in those samples. Other research, however, has suggested that semen from SBV RNA-positive bulls can indeed be infectious.

More research is needed to determine if the low concentrations of SBV RNA detected in semen pose a significant risk of transmission during artificial insemination. Further studies are essential to assess the infectivity of semen from SBV-positive bulls and to develop strategies for minimizing the risk of transmission.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1017/s0950268813002574, Alternate LINK

Title: Schmallenberg Virus Detection In Bovine Semen After Experimental Infection Of Bulls

Subject: Infectious Diseases

Journal: Epidemiology and Infection

Publisher: Cambridge University Press (CUP)

Authors: W. H. M. Van Der Poel, J. M. Parlevliet, E. R. A. M. Verstraten, E. A. Kooi, R. Hakze-Van Der Honing, N. Stockhofe

Published: 2013-10-09

Everything You Need To Know

What is the Schmallenberg virus (SBV), and what are its effects?

The Schmallenberg virus (SBV) is an arbovirus that affects domesticated ruminants, such as cattle and sheep. It can cause mild illness in adult cattle, including fever and diarrhea, and a reduction in milk production. The more significant impact is on pregnant animals, as SBV is linked to abortions and birth defects in their offspring, leading to substantial economic losses for farmers.

What did the study discover about Schmallenberg virus (SBV) in bovine semen?

The study revealed that the Schmallenberg virus (SBV) RNA can be found in the semen of infected bulls. The highest concentrations of SBV RNA were observed during the first week following infection. However, the study also showed that the amount of virus in semen was relatively low, and the virus might not be viable. This raises questions about the risk of transmission through artificial insemination practices.

Why is detecting Schmallenberg virus (SBV) in semen a concern?

The detection of Schmallenberg virus (SBV) RNA in bovine semen is concerning because it introduces the possibility of spreading the virus through artificial insemination (AI). While the study indicates low concentrations and potentially non-viable virus, the use of semen from infected bulls could still pose a risk. This underscores the need for careful monitoring and potentially screening semen for SBV to prevent the virus from spreading to other herds and causing adverse health and economic impacts.

When was the highest concentration of Schmallenberg virus (SBV) found in semen, and what other symptoms were observed?

The research found that the highest concentrations of Schmallenberg virus (SBV) RNA in semen were present in the first week after the bulls were infected. During this time, the bulls also experienced viremia, fever, and diarrhea. This suggests a correlation between the active infection stage and the presence of SBV in semen. However, the study highlights that viable SBV was only isolated from blood samples and not from semen, complicating the assessment of transmission risks.

What further research is needed regarding Schmallenberg virus (SBV) in semen?

The findings about Schmallenberg virus (SBV) in semen suggest that further research is needed to fully understand the risks associated with artificial insemination. Future studies should focus on determining the viability and infectivity of SBV in semen, as well as the potential for different AI practices to spread the virus. Furthermore, the detection of SBV RNA in lymph nodes connected to genital tissues indicates potential reservoirs for the virus, which should be investigated to gain more insight into the virus's transmission dynamics.