As in humans, various influenza viruses (e.g. the highly pathogenic avian influenza A virus H5N1) are continually circulating in birds, sometimes spreading more and sometimes less but usually causing seasonal, regionally limited epidemics. However, the current 2021/2022 avian flu season is exceptionally severe and has already resulted in 48 million animals having to be culled on farms in Europe (as of October 3, 2022) . Fortunately, no humans in Europe have been infected so far; thus, the risk to the general population is considered low.
Colony-breeding seabirds are particularly at risk
While avian flu epidemics usually subside in the summer months, the current season has seen numerous outbreaks during these months as well. Currently, 37 European countries are affected, with the geographic extent reaching from Spitsbergen to southern Portugal and in the east to Ukraine [1, 2]. The virus normally spreads via migratory wild birds and can also be introduced into poultry farms. From the end of April to mid-August 2022, however, colony-breeding seabirds such as gannets, sea swallows and cormorants were particularly affected, some of whose populations are endangered as a result . Despite the unusually large number of infections in poultry and wild birds and numerous transmission events to various mammal species, no transmission to humans has been reported in Europe in recent years [1, 2].
Globally only few cases of mild disease in humans
However, the fact that no one in Europe has been infected with currently circulating avian flu viruses does not mean that the pathogen cannot be transmitted to humans. Worldwide, at least a few infections have occurred in humans in recent years, but those have been asymptomatic or mild . So far, all infections have been traced back to close contact with infected animals (live or dead), infectious animal products or excretions, while human-to-human transmission has not yet occurred. There is therefore no increased risk for the general population. Obviously, direct contact with sick or dead wild birds should be avoided. If such an animal is found, contacting the veterinary office is recommended. Persons who have an increased risk of exposure for occupational reasons should take adequate measures – e.g. protective clothing, cleaning, and disinfection – in order to protect against infection . In order to inactivate enveloped viruses such as avian influenza viruses, disinfectants with at least a limited spectrum of virucidal activity must be used.
Conclusion: The current bird flu epidemic, which is extremely threatening for wild birds and poultry, is currently not a cause for concern for the general population. The consumption of poultry products such as eggs or meat is also considered uncritical . However, since viruses can mutate or crossbreed with other viruses, it cannot be ruled out that one day a pathogen will develop that poses a danger to humans and spreads quickly from person to person. In order to be able to react quickly to such an event, the outbreak is continuously monitored at international level.
- European Centre for Disease Prevention and Control (2022) 2021-2022 data show largest avian flu epidemic in Europe ever. https://www.ecdc.europa.eu/en/news-events/2021-2022-data-show-largest-avian-flu-epidemic-europe-ever (accessed on October 26, 2022)
- European Food Safety Authority, European Centre for Disease Prevention and Control et al. (2022) Avian influenza overview June–September 2022. EFSA Journal 20: e07597. https://doi.org/10.2903/j.efsa.2022.7597
- Centers for Disease Control and Prevention (2022) Recommendations for Worker Protection and Use of Personal Protective Equipment (PPE) to Reduce Exposure to Novel Influenza A Viruses Associated with Severe Disease in Humans (last reviewed: March 8, 2022). https://www.cdc.gov/flu/avianflu/h5/worker-protection-ppe.htm (accessed on October 31, 2022)
- US Food & Drug Administration (2022) Questions and Answers Regarding the Safety of Eggs During Highly Pathogenic Avian Influenza Outbreaks (as of April 29, 2022). https://www.fda.gov/food/eggs-guidance-documents-regulatory-information/questions-and-answers-regarding-safety-eggs-during-highly-pathogenic-avian-influenza-outbreaks (accessed on October 31, 2022)