Enhanced influenza surveillance to detect avian influenza virus infections in the EU/EEA during the inter-seasonal period

Transmission to humans can occur when avian influenza is circulating in animals, especially when people are directly exposed without wearing appropriate levels of protective equipment, with an estimated low-to moderate risks for individuals exposed. During the summer months, seasonal influenza virus activity tends to be very limited, resulting in few cases of seasonal influenza infection and even fewer cases of hospitalisation and severe disease.

Ideally, all influenza positive specimens from sentinel sources should be typed and subtyped, augmented by year-round surveillance of influenza and other respiratory viruses. Sentinel surveillance systems are important for the monitoring of respiratory viruses in the EU/EEA, but these systems are not designed and are not sufficiently sensitive to identify a newly emerging virus such as avian influenza in the general population early enough for the purpose of implementing control measures in a timely way.

To identify sporadic severe human infections with avian influenza virus in hospital settings, the following approach is proposed:

• People admitted to hospitals with respiratory symptoms or other symptoms compatible with avian influenza virus infection should be asked about exposure to birds (wild birds or poultry) or other animals (dead or alive) in the two weeks before symptom onset or, if not available, before admission.
• Patients admitted to the hospital due to respiratory or other influenza related symptoms should be considered for influenza A/B testing.
  Testing for influenza virus of hospitalised patients with unexplained viral encephalitis/ meningoencephalitis in whom a causative agent cannot be identified should be considered.
• All influenza A-positive samples from hospitalised patients should be subtyped for seasonal influenza viruses A(H1)pdm09 and A(H3).
• Samples positive for influenza type A virus but negative for A(H1)pdm09 or A(H3) should immediately be sent to national influenza reference laboratories for further testing, subtyping and genetic analysis. Member States should ensure they have sufficient laboratory capacity to meet this need and future demands.

Raising awareness among all primary care workers and communicating the epidemiological situation is important in order to not miss or delay diagnosis of potential human cases. Raising awareness in primary care providers including consideration of specific enquiring about animal exposure would be a good practice: people who seek medical care during the summer period with respiratory or other symptoms compatible with avian influenza virus infection be asked about history of exposure to dead or sick animals within the two weeks before symptom onset, especially when there are ongoing outbreaks among animals in the area. Primary care clinicians should be educated on symptoms compatible with avian influenza infections and testing of symptomatic persons with a history of exposure should follow a risk-based approach according to the level of exposure as proposed in the published ECDC guidance documents ‘Investigation protocol of human cases of avian influenza virus infections in EU/EEA’ and ‘Testing and detection of zoonotic influenza virus infections in humans in the EU/EEA, and occupational safety and health measures for those exposed at work’.

ECDC encourages national public health authorities to provide messaging to the general public to avoid close contact with or touching of sick or dead birds (especially seabirds and wildfowl) and dead wild mammals.