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Volume 31, Number 7—July 2025
Dispatch
Evidence of Viremia in Dairy Cows Naturally Infected with Influenza A Virus, California, USA
Jason Lombard
, Chloe Stenkamp-Strahm, Brian McCluskey1, and Blaine Melody
, Chloe Stenkamp-Strahm, Brian McCluskey1, and Blaine Melody
Table
Summary of influenza A virus testing where viremia was detected by PCR in cows from 3 affected dairy herds in California, USA*
| Herd | Breed | No. lactating cows sampled | No. sampling periods | No. (%) lactating cows with RT-PCR–positive serum samples | Interval for each sampling period, d |
No. serum samples collected | |
|---|---|---|---|---|---|---|---|
| Onset of clinical signs to positive serum samples | First bulk tank milk detection to positive serum samples | ||||||
| A | Jersey | 40 | 2 | 11 (27.5) | 3, 10 | 14, 21 | 80 |
| B | Holstein | 74 | 3 | 5 (6.8) | 3, 9, 13 | 5, 11, 15 | 107 |
| C |
Holstein |
30 |
1 |
4 (13.3) |
5 |
14 |
30 |
| Total | 144 | 20 (13.9) | 217 | ||||
*RT-PCR, reverse transcription PCR.
1Current affiliation: Lonestar Epidemiology Consulting, Livermore, Colorado, USA.
Page created: May 23, 2025
Page updated: May 30, 2025
Page reviewed: May 30, 2025
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