Avian influenza surveillance in vaccinated flocks
Detecting silent virus circulation is a major challenge in vaccinated flocks, as vaccination markedly reduces mortality and clinical symptoms, which are traditionally used to identify the presence of the virus. Consequently, monitoring vaccinated flocks to control the spread of the virus is a complex issue. A study published in the international journal Emerging Infectious Diseases (EID) by scientists from Toulouse, affiliated with UMR IHAP (INRAE/ENVT), demonstrates that enhanced event-based surveillance, utilizing weekly samples from deceased ducks, is the most effective strategy for the rapid detection of the highly pathogenic avian influenza (HPAI) virus in duck farms vaccinated against HPAI. This approach proves to be more sensitive and timely in detecting the virus compared to sampling live ducks, thereby effectively reducing the risk of silent virus circulation.
The study indicates that enhanced event-based surveillance, based on weekly sampling of deceased ducks, provides the highest sensitivity, detecting up to 90% of infected flocks, and allows for earlier detection than all other surveillance strategies examined. This method is therefore more effective than monthly sampling of a random selection of live ducks (scheduled surveillance).
