Avian flu: Mutated flu virus can be dangerous for humans
The H5N1 virus, known as bird flu, is particularly dangerous for birds. However, five mutations of the virus are sufficient to be passed on from person to person through droplet infection. Then a handshake is enough to catch the virus.
After only five mutations, the avian influenza virus becomes a threat to humans Until now, birds were primarily affected by the H5N1 virus. However, according to a study published in Science magazine, it may only be a matter of time before bird flu spreads to people and becomes a pandemic. An international team of researchers led by Sander Herfst from the Erasmus Medical Center in Rotterdam in the Netherlands found that five mutations in the genetic makeup of the virus are sufficient to spread from person to person as a droplet infection. According to the study, the mutations could take place within a single virus type. Mixing different subspecies of the pathogen is not necessary, the researchers said. In her experiment, the virus could be controlled with drugs. The vaccines currently approved in Europe were also successfully used.
Experts are concerned that they do not consider a pandemic that is spreading worldwide to be unlikely. The researchers therefore focused on the question of which mutations take place in the genetic material of the pathogen in order to enable a droplet infection that would promote the rapid spread of bird flu from person to person. First, the virus' genetic make-up was altered at three specific locations to ensure that it could spread more easily among mammals. In the next step, the researchers infected ferrets with the pathogen, since they can be infected with human viruses and show a similar course of the disease. Additional ferrets were infected by swabbing from the nose of the infected animals. The researchers repeated this process several times to simulate a natural infection situation. When the virus was examined after some time had passed, the researchers found that in addition to the three deliberately mutated mutagenic positions, additional changes had occurred that led to the virus being able to spread better.
Droplet infection possible in avian flu In order to check whether the mutated virus may also be transmitted via the air, the researchers placed cages with healthy ferrets next to those with the infected animals. The terrifying result: Most of the healthy animals also fell ill. Five mutations were therefore sufficient to enable a droplet infection. It is particularly important that the five mutations can arise within a host and a single virus type. The pandemics of the past century have always been caused by viruses that developed when different types of viruses in a host animal formed a genetically new type. Because of the numerous H5N1 infections in birds that occur worldwide, it may only be a matter of time and chance before a human-to-human transmission occurs, the researchers said.
Further studies on this topic are presented in the science magazine. In another study, researchers report that two viruses with the necessary mutations for human-to-human transmission have already been found in the field. Using a mathematical model, they investigated which factors make other mutations more likely and which make them less likely.
Bird flu kills fatalities In 1997, people in Hong Kong became infected with the bird flu virus for the first time. To date, over 600 sick people have been registered, all of whom have had close contact with poultry. About half of the sufferers died from the consequences of the infection.
Avian influenza is an infection with the H5N1 influenza A virus. The letters "H" and "N" indicate pieces of protein on the envelope of the virus. The variants are numbered. After the H5N1 virus was first registered in Asia in the late 1990s, it spread to Europe, Africa and the Middle East. The pathogen is particularly dangerous for birds, of which a large number of the animals concerned die.
What are the symptoms of avian flu people? After an incubation period that has not yet been clearly defined, which experts specify as two to 17 days, the usual symptoms of flu usually appear. In addition to very high fever, sufferers suffer from cough, shortness of breath and sore throat. In some cases, diarrhea, abdominal pain and vomiting occur. As the disease progresses, pneumonia and gastrointestinal complaints often occur. Some patients also suffer from kidney weakness, which can lead to kidney failure. If the infection is fatal, the cause is usually lung or multi-organ failure. (ag)
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