Should you be worried about the bird flu? What experts say after Texas dairy worker’s infection

The current hen flu an infection in a dairy employee in Texas has public well being officers on excessive alert, although consultants say the virus hasn’t turn into extra contagious, both amongst cows or individuals.

Samples taken from the affected person — whose solely symptom was pinkeye — confirmed that the virus has not modified in ways in which would make it straightforward for it to unfold from human to human, and that presently accessible vaccines and medicines stay efficient towards it, in line with the Facilities for Illness Management and Prevention.

“Our evaluation of the chance of avian flu to most of the people proper now stays low,” Dr. Nirav Shah, principal deputy director of the CDC, mentioned in an interview Wednesday. “Nonetheless, make no mistake, we’re taking this very significantly.” 

Upon studying from the U.S. Division of Agriculture final week that cows in a handful of dairy farms had examined constructive for hen flu, the CDC contacted state well being departments, asking them to work with farms to establish any one who could also be exhibiting signs.

“The case that we present in Texas, we discovered it as a result of we went to search for it. We knew to search for it,” Shah mentioned. 

This present type of hen flu, a pressure known as H5N1, has been circulating in birds world wide since late 2021. It has contaminated and killed numerous wild birds in addition to led to the culling of tens of thousands and thousands of birds on poultry farms throughout america.

The primary human case within the U.S. was in 2022, in a jail inmate in Colorado who was engaged on a poultry farm. The case in Texas is the nation’s second.

In a press briefing Wednesday, Tedros Adhanom Ghebreyesus, director-general of the World Well being Group, mentioned the company is in shut contact with the CDC.

“Any case of H5N1 is regarding as a result of it’s extremely harmful to people, though it has by no means been proven to be simply transmissible between individuals,” Tedros mentioned.

Whereas the 2 U.S. instances have each been gentle, H5N1 infections outdoors the nation have had a excessive mortality fee. 4 instances in Cambodia had been reported in February; one affected person died. In 2023, there have been six instances in Cambodia, 4 of which had been deadly. 

What are hen flu signs? 

Chicken flu is a respiratory virus. In extreme instances in people, it could trigger pneumonia, in line with the CDC. Signs can embrace fever, cough, sore throat, runny nostril, physique aches, complications, fatigue and shortness of breath or problem respiration. 

Instances may also be gentle: Within the 2022 case in Colorado, the person skilled just a few days of fatigue. 

The one symptom that the Texas affected person developed was conjunctivitis, or pinkeye, and the particular person is recovering, in line with the CDC. The company just isn’t conscious that any of the particular person’s shut contacts have developed flu-like signs, Shah mentioned. 

Nonetheless, what makes this explicit case totally different is the hyperlink to cows; the worry is that the virus will mutate in a manner that permits it to unfold extra simply amongst mammals and probably people.

“I don’t assume that this information implies that a flu pandemic is imminent,” mentioned Angela Rasmussen, a virologist on the Vaccine and Infectious Illness Group on the College of Saskatchewan. 

“I feel that because of this we’re getting yet one more early warning sign that if H5N1 has sufficient alternatives to get into mammals, it’s going to do what viruses at all times do and it’s going to proceed to adapt, to rising in them, as a result of that’s what viruses do.”

Is the hen flu virus altering?

Cows had been possible uncovered to the virus from some kind of interplay with a hen. 

“It might have been with hen feces. It might have been with a useless hen,” Shah mentioned. 

Samples of the virus taken from the Texas affected person in addition to from a handful of contaminated cows have been sequenced.

Rasmussen mentioned that the genetic sequencing of samples taken from cows confirmed that the virus was rather more intently associated to birds, suggesting it hadn’t been transmitting in cows for very lengthy and hadn’t had the prospect to mutate to unfold extra effectively amongst them.

The virus pattern taken from the affected person had one extra mutation that’s linked to unfold in mammals. Shah mentioned that the change has been seen “in quite a few different conditions, going again 20 plus years” and isn’t related to sustained unfold between individuals.

The mutation is just one of a “constellation of those totally different mutations which have been related to mammal to mammal transmission,” Rasmussen mentioned. “So it actually doesn’t appear like that is completely tailored to mammal to mammal transmission, in order that’s excellent news.” 

Then again, she mentioned, “it’s nonetheless actually early days. We’ve solely simply appreciated that the extent of an infection in cattle could be actually, actually underestimated. So there’s much more analysis, I feel, that we have to do to strive to determine how widespread that is in cattle and different individuals would possibly doubtlessly be in danger.”

One of many large questions that shall be key to stopping additional unfold, whether or not amongst cows or from cows to individuals, is knowing how cows themselves transmit the virus. 

In birds, Rasmussen mentioned, the virus grows within the gastrointestinal tract. Different birds get sick if they arrive into contact with contaminated saliva, mucous or feces. 

People can get sick in the event that they contact one thing with the virus on it after which contact their mouth, eyes or nostril, the CDC says. They’ll additionally breathe it in in the event that they’re in an space with loads of virus particles in mud or droplets. In response to Rasmussen, the virus can bind to receptors deep in people’ lungs, however not larger up within the respiratory tract, just like the nostril or mouth, which makes it exhausting to unfold from human to human. 

It could additionally bind to receptors within the eyes. That the Texas affected person’s symptom was pinkeye “means that they didn’t get it by inhalation, they acquired it from direct contact with cattle after which perhaps from rubbing their eyes or one thing like that,” she added.

It’s unclear how cows are contaminated and shed the virus, although. “It’s actually, actually exhausting to attempt to assess what the dangers are to individuals round cows, if we don’t know the place most of that virus is coming from on the cows,” Rasmussen mentioned. 

Pasteurized milk is protected to drink, in line with the Meals and Drug Administration, as a result of the method kills the virus.

What’s extra, any milk from an affected cow is thrown out earlier than it could enter the milk provide, one other step in maintaining it protected, Shah mentioned.