After an absence of around three months, highly pathogenic avian influenza (HPAI) has been identified in two French poultry flocks. Both are in the southwestern portion of the country, and were reported to have been discovered last week by the Ministry of Agriculture to the World Organisation for Animal Health (OIE).

During routine surveillance, samples from a flock of 1,875 domestic ducks at Vaureilles in the region of Aveyron tested positive for the H5N2 variant of the virus, and were subsequently euthanized. The birds had shown no clinical signs of the disease. According to the French agriculture ministry, the flock comprised 2,080 6-week-old ducks that were ready for gavage, and 2,917 ducklings 2 weeks of age.

Two days later, at La Dornac in Dordogne, a free-range broiler flock of 4,400 birds experienced unusually high mortality, which continued over the following days. Around 1,000 birds died. The presence of the H5N1 subtype of the HPAI virus was confirmed, and all the surviving birds have been destroyed.

Standard disease control measures have been established at both locations, including a 3-kilometer protection zones and 10-kilometer surveillance zone.

These latest cases bring the total number of HPAI outbreaks in France since November of 2015 to 79, according to the Ministry of Agriculture. This is the first outbreak recorded in the department of Aveyron, while the total for Dordogne now stands at 16.

Source of infection difficult to determine

In neither case could the source of infection be identified definitively.

An extensive survey of the non-migratory bird population in southwest France has revealed no evidence of these animals representing a reservoir of H5 or H7 avian influenza viruses, according to the French Agency for Food, Environmental and Occupational Health & Safety, ANSES.

Although it cannot rule out the possibility that wild birds can transmit the virus, ANSES concluded that they do not currently pose a substantial risk to domestic poultry directly or through the re-infection of farms prior to restocking.