The teenager hospitalized with bird flu in British Columbia, Canadamay have a variation of the virus that has a mutation that makes it more transmissible among people, early data show – a warning of what the virus can do that is especially worrisome in countries like the US where some H5N1 cases go undetected does not become
The US is “absolutely” not testing and monitoring bird flu cases enough, which means scientists can miss mutated cases like this, says Richard Webby, a virologist at St Jude Children’s Research Hospital’s Department of infectious diseases.
“We have to follow it as closely as possible. Any advanced warning that we can get that there are more viruses making these types of changes, that’s going to give us the notice,” Webby continued.
The Canadian teenager first developed symptoms on November 2 and was hospitalized at British Columbia Children’s Hospital on November 8. The child is still in critical condition with acute respiratory distress – a serious lung condition that can be fatal.
Preliminary sequencing of the H5N1 variant that sickened the teenager revealed a potential mutation at the genomic site known to make people more susceptible to the virus.
This may indicate that H5N1 has the ability to become more like a human virus, rather than a bird virus, but it is also not yet clear whether this change is significant and more dangerous for humans, experts said.
The virus may have mutated over the course of the teenager’s illness; additional sequencing may reveal more about its evolution.
“Often it’s not just one thing that will confer that ability” to infect people more effectively, said Angela Rasmussen, a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan.
“It’s not entirely clear what the real implications are going to be, but all of these things are definitely a warning sign,” Rasmussen said. “We really need to pay attention to this, and we really need to try to reduce more human infections as much as possible.”
The particular variant of H5N1 circulating among birds in British Columbia and the northwestern U.S. appeared in the past few months, several years after bird flu was first found in North America, Webby said. The variant also sickened 11 workers in Washington state who killed infected poultry, although the workers did not detect the possible mutation in the teenager.
“It seems to be pretty active in terms of infecting animals, infecting people, so I think it’s one to watch,” Webby said. “It has some unique properties that we just have to keep an eye on.”
No additional cases have been detected among the Canadian teenager’s contacts, including family, friends and healthcare workers. The teenager’s case was detected through disease surveillance – the regular examination of positive flu cases – at the hospital, and no other cases in the area were discovered through this system.
“We have strong flu surveillance in BC and have had an increase in test requests for H5 and all negative to date,” said Bonnie Henry, an epidemiologist, physician and provincial health officer at the British Columbia Ministry of Health. .
Canadian officials conducted blood tests among the teenager’s contacts, and they expect results later this week. They are also waiting for the results of other tests that were done at the weekend.
Officials are “still hopeful on the exposure side to find out how the young person was infected, but nothing new to report,” Henry said.
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Although there have been outbreaks of H5N1 among poultry in British Columbia, the teenager has not had exposure to it — but he or she has had contact with various pets, including dogs, cats and reptiles.
It’s possible that one of these animals came across a dead bird or animal and transmitted the virus to the teenager, Rasmussen said, adding: “I don’t think people realize how often we can come into contact with wild animals, including birds don’t come.”
Canadian officials have been working to fast-track cases like this, Rasmussen said.
“There is always more supervision you can do. However, it’s not like the US where they seem to be actively resisting animals and people,” said Rasmussen.
“It’s absolutely amazing to me that they don’t test every animal on a farm after it’s found to be infected,” she said. Farm owners and workers have been, and workers often are, resistant to testing for social, financial and legal reasons kept in the dark about outbreaks – making them a greater risk of getting sick.
In Canadaexperts hope the mutated virus will die out without being transmitted to anyone else. “If there are any additional human cases, those will also be isolated, and that means this virus has hit a dead end, evolutionarily,” Rasmussen said.
But if the mutation has happened once, it can happen again — a particular concern among less well-monitored populations, she said.
“If we have human cases that go undetected, it increases the risk that some of these viruses can be transmitted, and by the time we detect them, they may have spread further,” Rasmussen said. “That’s why we have to be very vigilant about this.”
The possibility of a more transmissible virus was a warning sign, Webby said. It “underscores the need for us to do something about this virus. We have to get it under control.”
