What exactly happened?
The Texan – authorities have not disclosed details about the person – is doing well: the person only suffered an eye infection from the virus. That in itself is not a cause for great alarm, says Koopmans: it often happens that people contract the bird flu virus after direct contact with infected animals.
“The reports from America speak of a fairly high virus load in cows. So this is not completely illogical,” says Koopmans. “It is of course a strange development. And further information is needed quickly.”
One of the biggest questions experts like Koopmans have is whether the virus has developed the ability to pass from cow to cow. “It certainly seems that way,” Koopmans notes. Bird flu has also emerged on a dairy farm in Michigan. That company had recently imported cows from one of the infected herds in Texas.
Is a new pandemic now threatening?
Probably not right away. The signs seem favorable: for example, the bird flu virus has not yet undergone any of the mutations known to scientists that allow it to spread better through the air. The infected Texan also does not appear to have passed the virus on to other people.
The American health service CDC therefore estimates the risk for people who have not had direct contact with an already infected animal to be low. Infected herds do not need to be culled. The CDC’s guidelines are: avoid contact with infected animals, pay attention to suspicious symptoms, and ensure that infected people go into isolation.
How often does it happen that people become infected with the bird flu virus?
Since H5N1 suddenly became much more contagious to birds in 2020, at least five Britons, two Spaniards, a Chilean, an American and a girl from Ecuador have been infected with it, according to figures from the World Health Council, always after direct contact with infected birds.
These are remarkably low numbers, considering the virus has spread almost worldwide and infected hundreds of millions of birds. Apparently the variant that is so prevalent among birds is not very contagious to humans.
The situation is slightly different with a variant of H5N1 circulating in Asia. People regularly become infected there, often with serious consequences. For example, last week it was announced that a 21-year-old student in Vietnam had died of bird flu after catching birds. A month earlier, a 9-year-old boy in Cambodia died after eating contaminated duck and chicken.
As a rule, this concerns the ‘clade’ (branch on the virus family tree) referred to as ‘2.3.2.1.c’, a slightly different variant of H5N1. Between 2003 and 2019, this variant was prevalent in Asia and Egypt in particular: 861 people were infected, more than half of them died.
But 2.3.2.1c has not disappeared yet. When an 11-year-old girl in Cambodia died of bird flu a year ago, it turned out that the 2.3.2.1c variant of H5N1 was not responsible. It was extra worrying that the girl also infected her father: a sign that human-to-human spread is lurking.
Where did the Texas outbreak come from?
That is quite puzzling, because it has never happened before that the bird flu virus (the ‘Western’ variant) infected ruminants. Last week it was announced that the virus has emerged in two herds of dairy cows in Texas and two in Kansas. Dead birds were found on some farms: an indication that the virus reached the cows through contaminated water or food.
The cows became ill, but not seriously. They had an increased temperature, less appetite and gave less milk. Some cows also gave thick, discolored milk. Much further north, in the state of Minnesota, several young goats died after being infected with the virus. The goats lived on a hobby farm where there was an outbreak of H5N1 among the poultry.
What exactly is the threat in the air?
There are no influenza viruses of the H5 type circulating among humans yet; all known ‘human flu’ is of the H1, H2 or H3 type. As a result, the human immune system does not recognize bird flu and, in theory, people could become more seriously ill if an H5 virus spreads. The flu shot cannot provide protection either.
However, there are various candidate vaccines in the pipeline that appear to provide reasonable protection against H5N1. In addition, there are antiviral drugs on the market that seem to help against bird flu. “Preliminary analyzes of H5N1 have not identified any mutations that would make these viruses resistant to currently approved antiviral medications,” the CDC said in a statement.
