Avian influenzaU69.21!

Bird flu" (avian influenza) is a disease caused by influenza A viruses in birds. These avian viruses can combine with human viruses through reassortment and thus become pathogenic to humans (Kim SM et al. 2016). The transmission of H5N1 viruses from humans to humans has now been proven, but the risk of transmission is extremely low. If such an infection occurs, the disease can sometimes be very severe. There is currently no evidence worldwide of continued human-to-human transmission with avian influenza viruses (see the basic principles in the "Report on the epidemiology of influenza in Germany 2018/19 season", from page 107. See the WHO monthly risk assessment on avian influenza from 3.5.2024).

Avian influenza (A/H5N1) and (A/H7N9) comprises around 15 different avian influenza viruses and is a highly contagious disease exclusively for birds.

In humans, the symptoms are similar to those of severe influenza. The disease begins about 2 to 5 days after infection (incubation period).

According to the WHO, more than 2,600 human cases and 1,100 deaths from avian influenza have been recorded worldwide since 2003, primarily in the Asia-Pacific region. The infections mainly affected the subtypes A(H7N9) and A(H5N1). However, other avian influenza viruses have also been detected in humans (including A(H5N6), A(H9N2) / (Li YT et al. 2019). In 2024, an infection with influenza A(H5N2) was detected for the first time in a case in Mexico. Apparently, infections primarily occur through close contact with sick or dead birds and their products or excrement. In Germany, no human cases of avian influenza viruses have been reported to date.

Transmission of A(H5N1) to other mammals (presumably through contact with infected birds, poultry or their excrement). Affected are mainly carnivorous wild animals, which presumably became infected from dead wild birds. The risk of humans becoming infected with bird flu viruses through contact with sick/dead mammals (wild, stray or domestic) is estimated to be low (RKI=Robert Koch Institute).

As part of the global A(H5N1) outbreak that has been ongoing for several years, the virus was also registered for the first time in dairy cow herds in various states in the USA in March and April 2024.

Symptoms of bird flu in humans: high fever, headache and sore throat, cough, aching limbs, shortness of breath

The following symptoms may also occur: severe diarrhea, nausea, abdominal pain

The known cases of H5N1 infection in humans who have had close professional contact with presumably infected dairy cows have been relatively mild (conjunctivitis; respiratory symptoms).

Based on the symptoms described by the patient (such as fever, cough, shortness of breath), a travel history should be taken. If the patient has been in an affected avian influenza area within the last 7 days and has had contact with wild birds or poultry, the doctor may suspect avian influenza. A rapid influenza test (throat or nasal swab) can then be used to determine whether or not the patient is infected with an avian influenza pathogen.

Preparations with"neuraminidase inhibitors" are effective against the current avian influenza virus H5N1 according to current findings. This is the result of in-vitro studies and animal experiments with this influenza virus. There is not yet sufficient clinical experience for humans infected with the current H5N1 avian influenza virus.

In general, you should not touch sick or dead (wild) birds or (wild) animals, but contact the competent veterinary authority. However, if contact with wild birds or infected poultry cannot be avoided, e.g. for professional reasons, adequate protective measures should be taken to minimize the risk of transmission to humans. The RKI has published recommendations on its website for the prevention of persons with an increased risk of exposure to avian influenza A(H5) (highly pathogenic for birds).

Suspected cases, cases of illness and deaths with avian influenza virus infection in humans (zoonotic influenza) are notifiable and must be reported to the responsible health authority (Infection Protection Act §6 (1) 1. s)).

1. Horman WSJ et al. (2018) The Drivers of Pathology in Zoonotic Avian Influenza: The Interplay Between Host and Pathogen. Front Immunol 9:1812.
2. Kim SM et al. (2016) Avian Influenza A Viruses: Evolution and Zoonotic Infection. Semin Respir Crit Care Med 37:501-511.
3. Li YT et al. (2019) Avian influenza viruses in humans: lessons from past outbreaks. Br Med Bull. 2019 Dec 11;132(1):81-95.
4. https://www.ecdc.europa.eu/en/avian-influenza-humans/surveillance-and-disease-data