No Evidence of H5 Avian Influenza in Iranian Dairy Cattle: A Serological Survey and Review of Global Spillover Cases

Fallah Mehrabadi, Mohammad Hosein; Ziafati, Zahra; Hosseini, Hossein; Abdoshah, Mohammad; Motamed, Najmeh; Akhijahani, Mohsen Mahmoudzadeh; Mohammadi, Reza; Jamali, Abbas; Jamiri, Fahime; Bakhshi, Alireza; Mehrad, Mahboube Kanafi; Sarmadi, Soroush; Ghalyanchilangeroudi, Arash

doi:10.22092/ari.2026.371492.3956

No Evidence of H5 Avian Influenza in Iranian Dairy Cattle: A Serological Survey and Review of Global Spillover Cases

Articles in Press

Document Type : Original Articles

Authors

¹ Department of Poultry Disease diagnostics, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization (AREEO) , Karaj, Iran

² Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran

³ Department of Clinical Sciences, Faculty of Veterinary Medicine, Karaj Branch, Islamic Azad University, Alborz, Iran

⁴ Department of Poultry Vaccine Production, Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension, Karaj, Iran

⁵ Department of Influenza Research and other Respiratory Viruses, Pasture Institute of Iran,Tehran,Iran

10.22092/ari.2026.371492.3956

Abstract

Avian influenza viruses, especially highly pathogenic H5 (HP), are significant pathogens that pose major risks to both animal and human health, as well as causing substantial economic losses in the poultry industry. Recent global reports have highlighted the spillover of highly pathogenic H5 avian influenza (AIV) into dairy cattle, raising concerns about the virus's zoonotic potential and transmission pathways. This study evaluated current knowledge of H5 AIV in cattle in Iran, critically analyzing serological data and assessing the virus's ability to cross species barriers through a survey of dairy farms in Qazvin and Isfahan provinces, Iran, during 2024-2025. It involved testing 500 dairy cattle of various ages, breeds, and lactation stages. All samples tested negative for H5 antibodies using the hemagglutination inhibition (HI) test, which contrasts with international reports of H5 spillover in cattle, particularly in North America. The report notes the limitations of the HI test, including its low sensitivity to small levels of antibody in the cattle sera, and recommends supplementary diagnostic methods along with continuous surveillance for better detection. The lack of detected antibodies may indicate no exposure or little viral circulation below detection levels. These results highlight the importance of ongoing surveillance, especially in regions close to wild bird flyways and intensive poultry farming areas, assessing risks related to the dairy farm workers during HPAI outbreaks. The findings emphasize the need for targeted monitoring and risk assessment systems to manage emerging zoonotic threats, considering H5 AIV's capacity for cross-species adaptation and the rising frequency of global spillover events.

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