According to the latest report published by the European Food Safety Authority (EFSA), between the end of June and 1 September 2023, highly pathogenic avian influenza (HPAI) outbreaks continue to be reported worldwide. 

These are worrying results, especially regarding infections in mammals: numerous cases occurred in raccoon dogs, foxes, and American mink kept for fur, as well as in wild otters and seals. Occasional infections in domestic cats and dogs have also been recorded. Some strains now have developed mutations that improve the virus’ ability to infect human cells, increase its resistance to certain antivirals, and augment its virulence. Research is ongoing into the effects of such mutations, but these new subtypes could have a higher zoonotic potential (not yet demonstrated). 

What is clear is that some of the circulating HPAI variants have the ability to jump from one species to another. For instance, it is believed that A(H5N1) which carries markers for adaptation to mammalian cells jumped from chickens to cats in one outbreak in Poland. On Finnish fur farms, the virus jumped from wild birds to kept mammals and further mutated once inside the farms. For this reason, the EFSA recommends increasing biosecurity in fur farms and promptly culling all animals in case of a HPAI outbreak. As long as fur farming remains lawful in the EU, we can thus expect more mass culling events like those witnessed in recent years and even very recently due to COVID infections in animals. 

For now, human infections are infrequent and are therefore considered sporadic, usually as a consequence of direct human contact with infected poultry. However, the situation is evolving and the EFSA recommends consistent and continued monitoring of outbreaks in wild and domestic animals.

Recommendations from the report include:

• Increased surveillance of the circulation of the virus both in wild birds and in free-living domestic carnivores;
• Increased biosecurity in fur farms with prompt culling of all animals in case of a confirmed outbreak of HPAI, because of the increased risk of mammalian adaptation of the virus;
• Timely and accurate reporting of cases in mammalian species for epidemiological purposes;
• Both people and domestic carnivores should avoid contact with infected carcasses;
• Hospitalised human patients with severe respiratory symptoms should be assessed for exposure risk to HPAI.

Of particular concern is the finding that “about 47% of the characterised viruses contain at least one of the adaptive markers associated with increased virulence and replication in mammals [...]. These mutations with potential public health implications have likely emerged upon transmission to mammals.” 

Additionally, in April 2023 a HPAI virus identified in farmed dogs in China had a key mutation that would allow it to jump directly from birds to humans. 

As this report was published, South Africa was (and still is) dealing with the devastating economic consequences of its latest HPAI outbreak, which has resulted in the culling of several million broiler chickens and laying hens. A vaccination program will probably begin in the coming weeks.