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Volume 31, Number 1—January 2025
Research
Surveillance Strategy in Duck Flocks Vaccinated against Highly Pathogenic Avian Influenza Virus
Sophie Planchand, Timothée Vergne
, Jean-Luc Guérin, Séverine Rautureau, Guillaume Gerbier, and Sébastien Lambert
, Jean-Luc Guérin, Séverine Rautureau, Guillaume Gerbier, and Sébastien Lambert
Table 1
Description of surveillance strategies used in duck flocks vaccinated against highly pathogenic avian influenza virus*
| Surveillance strategy |
Description |
Case definition assumed to trigger an alert |
Additional information |
|---|---|---|---|
| Passive | |||
| P1 | Daily proportion of dead ducks found on the farm | Daily percentage of dead ducks exceeds a predefined threshold | Thresholds used: 0.1%, 0.2%, and 0.5% |
| P2 | Weekly proportion of dead ducks found on the farm | Weekly percentage of dead ducks exceeds a predefined threshold | Thresholds used: 0.5%, 1%, and 3% |
| P3 |
Ratio of the daily influenza mortality to the natural daily mortality |
Ratio exceeds a predefined threshold |
Thresholds used: 5×, 10×, and 20× natural daily mortality |
| Enhanced passive |
RT-PCR testing of a predefined number of randomly selected dead ducks or of all dead ducks if less than the predefined number, at predefined intervals |
At least 1 selected dead duck tested positive |
Intervals used: 7 and 14 d; no. selected dead ducks: 3, 5, and 7 |
| Active | RT-PCR testing of 60 live ducks randomly sampled at predefined intervals | At least 1 selected live duck tested positive | Intervals used: 20, 30, and 40 d |
*RT-PCR, reverse transcription PCR.
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