Bovine Alphaherpesvirus-1 Infection in Dairy Cattle Herds in Khorasan Razavi province, Iran: Herd-Level Prevalence in Bulk Tank Milk, Risk Factors, and Regional Insights

Dorostkar, Saeed; Mohammadi, Gholamreza; Haghparast, Alireza

doi:10.66224/ari.2026.372286.4056

Bovine Alphaherpesvirus-1 Infection in Dairy Cattle Herds in Khorasan Razavi province, Iran: Herd-Level Prevalence in Bulk Tank Milk, Risk Factors, and Regional Insights

Articles in Press

Document Type : Original Articles

Authors

¹ Department of clinical sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad-Iran.

² Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.

³ Department of Pathobiology, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad-Iran

10.66224/ari.2026.372286.4056

Abstract

Introduction: Bovine alphaherpesvirus-1 (BoHV-1) causes infectious bovine rhinotracheitis, reproductive disorders, immunosuppression, and major economic losses in dairy cattle. This cross-sectional study estimated herd-level prevalence of BoHV-1 in industrial dairy herds of Khorasan Razavi province, Iran, using bulk tank milk (BTM) samples and identified associated risk factors.
Materials and Methods: A total of 160 industrial dairy herds were sampled. BTM samples were tested for BoHV-1 antibodies using a commercial indirect ELISA.
Results: Apparent prevalence was calculated as the proportion of positive herds, and true prevalence was estimated using the Rogan-Gladen method. Herds were categorized as small (6–50 cows), medium (51–100 cows), or large (101–1050 cows). Associations between BoHV-1 positivity and herd characteristics were assessed using chi-square tests and logistic regression.
The apparent herd-level prevalence was 66.9% (107/160), and the adjusted true prevalence was 70.2%. Prevalence increased significantly with herd size, from 48.8% in small herds to 79.2% in medium herds and 93.8% in large herds (P < 0.001). Logistic regression showed significantly higher odds of BoHV-1 positivity in medium herds (OR 9.0) and large herds (OR 19.3) compared with small herds. Although resident artificial insemination technicians were initially associated with positivity, this effect was not significant after adjustment for herd size.
Conclusion: BoHV-1 prevalence is high in industrial dairy herds of Khorasan Razavi, and larger herd size appears to be the main risk factor. Targeted vaccination, improved biosecurity, and active surveillance are recommended.

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