When a bird flu virus hit a large poultry farm in Russia earlier this year, it was a reminder that the coronavirus causing the pandemic was not the only dangerous virus.
Authorities quickly tested the birds and moved at high speed, killing 800,000 chickens, discarding the carcasses and clearing the farm to stop the potential spread to other chicken farms. But they were also concerned about people.
They tested the birds and sequentially determined the virus and determined that it is the H5N8 strain of bird flu, which is very dangerous for wild and domestic birds. It is located in Asia and causes increasingly deadly bird outbreaks in Europe. H5N8 viruses have infected a number of poultry herds in the United States, but the viruses come from a different, though related lineage, unlike the current H5N8 viruses in Asia and Europe. Influenza viruses often combine and mutate in unpredictable ways.
In the short period from 25 December 2020 to 14 January this year, more than seven million birds were lost due to the H5N8 outbreaks in Europe and Asia. Europe alone had 135 outbreaks among poultry and 35 among wild birds. To put the numbers in context, people naturally consume about 65 billion chickens a year, and one estimate puts the number of chickens in the world at 23 billion.
As harmful as H5N8 was to birds, humans have never infected it. Until February. The Russian health authorities also tested about 200 of the people involved in cleaning up the farm in Astrakhan using nasal swabs and later blood tests for antibodies. They reported that H5N8 jumped on humans for the first time. It appears that seven of the workers were infected with the virus, although none of them became ill. However, only one of the seven cases was confirmed by genetically sequencing the virus.
Nevertheless, the potential danger of the new virus and its outbreak has alarmed humans for Dr. Daniel R. Lucey, a physician and pandemic specialist at Georgetown University.
For Dr. Lucey seemed like no one else considered the contamination of people with H5N8 as ‘of concern’. He added: “I think it’s worrying.”
Other scientists have said they are not so worried.
Dr. Florian Krammer, a flu researcher at the Icahn School of Medicine in Mt. Sinai, said he was more concerned about other bird flu viruses such as H5N1 which have already been shown to be dangerous to humans. Another bird flu virus, H7N9, first infected humans in 2013. There have since been more than 1,500 confirmed cases and more than 600 deaths. Since 2017, there have been only three confirmed cases and the virus does not jump easily from person to person.
It is always possible that any virus can develop from person to person and become more dangerous. But H5N8 would have both hurdles to jump. Compared to other viral threats, dr. Krammer said, “I’m not worried.”
Dr. Richard J. Webby, a flu specialist at the St. Jude Graduate School of Biomedical Sciences and director of the WHO’s Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds, said all the H5 viruses are of concern because some of them have infected and killed humans. But he said: “They all have the same binding capacity to human cells, which is limited,” he said. Influenza viruses use a slightly different way of attaching to cells in birds than to cells in humans and being good usually means that you are not good with others.
Dr. Webby also said that although seven infections would certainly be of concern, only one infection was confirmed. The tests of the other six involved nasal swabs and blood tests. In people without symptoms, nasal swabs can simply indicate that they have inhaled virus. That would not mean it infected them.
Blood antibody tests also have the potential for errors, he said, and could not distinguish exposure to one flu virus from another.
He also saw no scientific basis to suggest that H5N8 is more likely than any other bird flu to develop human-to-human transmission. But any virus can develop the ability.
Dr. Lucey said he was pleased to see that the U.S. Centers for Disease Control and Prevention prepared a candidate vaccine for H5N8 before it infected humans. Candidate vaccines are merely the first steps in planning possible problems, and they have not yet been undertaken. It exists for many viruses.
“People should regularly test those for the virus at the time of bird outbreaks,” said Dr. Lucey said. He is a proponent of the protocol followed in Astrakahn and argues that public health authorities should test people exposed to sick birds with nasopharyngeal swabs and an antibody test, followed by other antibody tests a few weeks later.
An upcoming editorial in the journal Travel Medicine and Infectious Disease also takes up the Astrakahn incident and calls for increased monitoring of all H5 viruses.