When an avian flu virus hit a major bird farm in Russia earlier this year, it reminded us that the pandemic coronavirus was not the only dangerous virus there.
Authorities quickly tested the birds and moved at high speeds, killing 800,000 chickens, removing carcasses and cleaning the farm to stop potential spread to other chicken farms. But they were also concerned with people.
They tested the birds and sequenced the virus, determining that it was the H5N8 strain of bird flu, which is extremely dangerous for both wild and domestic birds. It is established in Asia and has caused more and more outbreaks of birds in Europe. H5N8 viruses have infected some flocks of poultry in the United States, but the viruses come from a different, albeit virus-related, line distinct from current H5N8 viruses in Asia and Europe. Influenza viruses often combine and move in unpredictable ways.
In the short period from 25 December 2020 to 14 January this year, more than seven million birds were lost to H5N8 outbreaks in Europe and Asia. Europe alone had 135 outbreaks in poultry and 35 in wild birds. Of course, to put the figures in context, people consume about 65 billion chickens each year, and an estimate raises the number of chickens in the world at any time to 23 billion.
As harmful as H5N8 was to birds, it never infected humans. Until February. Russian health authorities also tested about 200 of those involved in cleaning up the Astrakhan farm, using nasal swabs and subsequent blood tests for antibodies. They reported that, for the first time, H5N8 jumped in humans. Seven of the workers appear to have been infected with the virus, although none of them became ill. However, only one of these seven cases was confirmed by genetic sequencing of the virus.
However, the potential danger of the new virus and its leap to humans has sounded alarm bells for Dr. Daniel R. Lucey, a physician and pandemic specialist at Georgetown University.
For Dr. Lucey, no one else seemed to take infecting people with H5N8 as “a concern.” He added: “I think it’s worrying.”
Other scientists have said they are not as worried.
Dr. Florian Krammer, influenza researcher at the Icahn School of Medicine in Mt. Sinai said it is 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 people in 2013. There have been more than 1,500 confirmed cases and more than 600 deaths since then. Since 2017, there have been only three confirmed cases, and the virus does not jump easily from person to person.
It is always possible for any virus to evolve from human to human transmission, as well as become more dangerous. But H5N8 would have both obstacles to jump. Compared to other viral threats, Dr. Krammer said, “I’m not worried.”
Dr. Richard J. Webby, influenza specialist at the University School of Biomedical Sciences St. Jude, director of the WHO Collaborating Center for Influenza Ecology Studies in Animals and Birds, said all H5 viruses are a concern because some of them have infected and killed people. But, he said, “They all have the same type of ability to bind to human cells, which is limited,” he said. Influenza viruses use a slightly different way of attaching to bird cells than to human cells, and being good at one usually means not being good at the other.
Dr. Webby also said that while seven infections would certainly be worrisome, only one infection has been confirmed. The tests of the other six involved nasal swabs and blood antibody tests. In asymptomatic people, he said, nasal tampons may simply indicate that they inspired the virus. That wouldn’t mean he infected them.
Blood antibody tests also have the potential for error, he said, and he may not be able to distinguish exposure to one flu virus from another.
Nor has he seen any scientific basis to suggest that H5N8 is more likely than any other bird flu to evolve from human to human transmission. But any virus could evolve this ability.
Dr. Lucey said he was encouraged to see that the US Centers for Disease Control and Prevention prepared a candidate vaccine for H5N8 before it infected humans. Candidate vaccines are simply the first steps in planning for potential problems and have not passed any tests. It exists for many viruses.
“People should be routinely tested for the virus, even at the time of the bird outbreak,” said Dr. Lucey. He is in favor of the protocol followed in Astrakahn and argues that for any outbreak among birds, public health authorities should test people who are exposed to sick birds with nasopharyngeal swabs and an antibody test, followed by other antibody tests a few weeks later. Late.
A future editorial in Travel Medicine and Infectious Disease magazine also takes up the Astrakahn incident and calls for increased monitoring of all H5 viruses.