Research for infection protection

H7N9 virus – symptoms, route of transmission and hygiene measures in case of avian influenza infections

On 01 April 2013, WHO first reported the occurrence of an avian influenza virus (subtype H7N9) in humans in China. “H” (hemagglutinin) and “N” (neuraminidase) stand for the most important proteins of the viral envelope. The source of infection is not known yet. However, it is presumed that those infected acquired the H7N9 infection via contact with poultry. The pathogen infests poultry; the infection may be completely asymptomatic. This complicates the detection of the source of infection and the virus is able to spread without being perceived. WHO assumes that human-to-human transmission of the bird flu virus has occurred in rare cases. There have been severe, even lethal infections in humans associated with H7N9; there is no vaccine available yet.

Transmission path and duration of infectiousness of avian influenza viruses

Avian influenza viruses may be transmitted by inhaling infectious particles during close contact with poultry, e.g. by hand/eye contact after having touched contaminated bird excrement, or by contaminated water. As a general rule, the time between being infected and the beginning of symptoms is between 2 to 5 days. Contagiousness starts with the occurrence of the first symptoms, which are similar to those of the seasonal influenza, and lasts for at least 4 to 7 days. The bird influenza viruses are usually not pathogenic to humans. However, when an infection occurs, this may involve a severe course of disease.

Hygiene measures in case of avian influenza viruses

Hygiene standards usual for influenza viruses should be followed in case of an infection. Disinfectants that are virucidal against enveloped viruses are suitable for disinfection. Most viruses are transmitted via hands. And when falling ill, it is particularly thorough hand disinfection that can contribute to preventing a spread to healthy people. In addition, it is advisable to wipe-disinfect near-patient surfaces and equipment/medical devices with direct patient contact each day. Where appropriate, disinfection measures should be extended to further surfaces.

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Additional information:
Robert Koch-Institut 2011: Influenza (Saisonale Influenza, Influenza A (H1N1) 2009, Aviäre Influenza). RKI Ratgeber für Ärzte
(in German)
Robert Koch-Institut 2013: RKI zu humanen Erkrankungsfällen mit Influenza A (H7N9) in China, Last update: 24 May 2018
(in German)