Mathews-Martin et al.
Persistence of Tick-Borne Encephalitis Virus in Goat and Cow Milks Under Different Storage Conditions and Following Thermal Inactivation. Food Environ Virol. 2025;17(2):26. doi:10.1007/s12560-025-09641-7
Consumption of non-pasteurized milk and dairy products from animals infected with tick-borne encephalitis (TBE) virus can lead to human infections. Alimentary transmission of TBE is relatively frequently reported in Slovakia (see e.g., Snapshot Week 16/2025, Snapshot Week 31/2022, Snapshot Week 16/2022), and a major outbreak occurred in the former Czechoslovakia, affecting over 600 individuals (see e.g., Newsletter April 2024).
The thermal inactivation of the TBE virus (strain Ain/France/2020) has been investigated using experimentally contaminated goat and cow milk subjected to standard dairy industry heat treatments. Under controlled laboratory conditions, the virus remained infectious in both cow and goat milk for up to 48 hours when stored at 4°C, with greater stability observed in goat milk. At 21°C, viral stability was significantly reduced in both types of milk.
Pasteurization at 72°C for 15 seconds successfully inactivated TBE virus particles in spiked goat milk; however, at a viral concentration of 10⁵ PFU/ml, infectious particles were still detectable in cow milk. Additionally, some virus particles remained viable even after heating at 63°C for 30 minutes. The authors suggest that differences in virus stability and heat inactivation may be attributed to variations in milk composition between species. Specific milk components—such as caseins, lactoferrin, immune factors, and unsaturated fatty acids—have demonstrated antiviral properties against orthoflaviviruses.
In summary, the study indicated that goat milk may exhibit a greater antiviral effect on free TBE virus particles compared to cow milk. The stability of naturally contaminated milk is likely influenced by the ratio of cell-free to cell-associated viral particles. Importantly, the unexpected finding that pasteurization was less effective in cow milk underscores the need to consider both the milk species and initial viral load when designing food safety protocols for thermal processing.