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Avian flu in humans
Medical expert of the article
Last reviewed: 05.07.2025
Bird flu is an acute zoonotic infectious disease with a predominantly fecal-oral mechanism of pathogen transmission. It is characterized by a pronounced febrile-intoxication syndrome, lung damage with the development of respiratory distress syndrome and high mortality.
ICD10 code
J10. Influenza due to identified virus.
What causes bird flu in humans?
Bird flu is caused by strains of influenza A that normally infect only wild birds (sometimes pigs). Infection with these strains has recently been found in humans.
Most human infections are caused by H5N1 strains of avian influenza, but H7N7, H7N3, and H9N2 also play a role. In wild animals, the infection is asymptomatic but causes high mortality in wild birds. The first human case was detected in 1997 in Hong Kong. Transmission to humans occurs from infected sick poultry. In 2003–2004, humans were infected with strains of avian influenza in various Asian regions (H9N2 and 2005 - H5N1), Canada (H7N3), and the Netherlands (H7N3). Although most cases are associated with contact with infected birds, human-to-human transmission may have occurred in the Netherlands and Asia.
All influenza viruses are capable of rapid mutation, which increases the potential for bird flu viruses to spread from person to person. This could occur through direct mutation or recombination with human strains in humans or intermediate hosts. Many experts believe that when the virus acquires these properties, a pandemic will occur.
What are the symptoms of bird flu?
Bird flu (influenza A (H5N1)) has an incubation period of 2-3 days, ranging from 1 to 7 days.
H5N1 avian influenza causes severe respiratory symptoms. The fatality rate was 37% in the 1997 epidemic and almost 80% in the 2004 epidemic. Infection with the H7 strain most often causes conjunctivitis, although in an outbreak in the Netherlands several patients had flu-like symptoms and one patient (out of 83) died.
What's bothering you?
How is bird flu diagnosed?
When clinically symptomatic patients are identified in areas where avian influenza is present, patients or infected birds should be considered for this infection. If the patient has returned from an area where avian influenza has occurred, he or she should undergo PCR testing for influenza A. No attempt should be made to culture the virus. If the disease is suspected or detected and confirmed, the Centers for Disease Control and Prevention should be notified.
What do need to examine?
How to examine?
What tests are needed?
How is bird flu treated?
Bird flu is treated with oseltamivir and zanavir, indicated in normal doses. The 2004 epidemic showed that the H5N1 strain is resistant to amantadine and rimantadine. Prevention is carried out by destroying infected bird flocks.
What is the prognosis for bird flu?
Bird flu has an unfavorable prognosis. Mortality is 50-80% in the second week of the disease.