The discovery of the fox with avian flu, virus H5N1 in a wild canid in the province of Zaragoza underscores the persistent viral circulation in wildlife, although authorities maintain a low risk for human health.
The health and veterinary authorities of Spain have confirmed the detection of the first case of avian flu in a mammal in Spain during the current epidemiological wave. The avian influenza virus of high pathogenicity (H5N1) was identified in a wild fox found dead in the autonomous community of Aragón, specifically in the province of Zaragoza.
The Ministry of Agriculture, Fisheries and Food (MAPA) was the entity responsible for reporting this event, which was verified by the Central Veterinary Laboratory of Algete (Madrid).
Although the case of the fox with avian flu is the first of its kind in a wild mammal in the country during this phase of the epidemic, experts categorize it as a “warning” that reinforces the need for surveillance, rather than a reason for immediate alarm.
Mechanism of Contagion and Viral Persistence
Researchers consulted by various media indicate that this type of transmission of H5N1 from birds to mammals does not necessarily imply a mutation of the pathogen to facilitate the species jump. The consensus is that the most likely contagion occurred through ingestion: the fox would have fed on the remains of dead or sick birds that carried a high viral load.
This explanation aligns with previous episodes of contagion in mammals recorded in Spain and other European countries, such as the outbreak previously detected in a mink farm in captivity.
The phenomenon, therefore, reflects an increase in the general circulation of the virus in wildlife, mainly in migratory birds such as cranes and seagulls, which have concentrated a large part of the national positives.
Risk for the Population of Foxes with Avian Flu and Surveillance Protocols
In light of the appearance of H5N1 in a terrestrial mammal, the Veterinary Collegiate Organization (OCV) has reiterated to the public that the risk of transmission of avian influenza to humans remains extremely low. Contagion to people is very exceptional and requires direct, repeated, and prolonged exposure to heavily contaminated environments or the handling of infected animals.
Authorities insist that the epidemiological surveillance system is active and operating rigorously, especially to monitor any possible change in the virus’s transmission capacity, such as a potential contagion from mammal to mammal, of which, so far, there is no evidence. The priority remains to protect domestic poultry farms through biosecurity measures and the confinement of birds.
