Not less than one particular person in Texas has been recognized with hen flu after having contact with dairy cows presumed to be contaminated, state officers mentioned on Monday.
The announcement provides a worrying dimension to an outbreak that has affected hundreds of thousands of birds and sea mammals worldwide and, most just lately, cows in america.
Up to now, there are not any indicators that the virus has advanced in ways in which would assist it unfold extra simply amongst folks, federal officers have mentioned.
The affected person labored straight with sick dairy cows, mentioned Lara M. Anton, a spokeswoman for the Texas Division of State Well being Providers. “Now we have examined round a dozen symptomatic individuals who work at dairies, and solely the one particular person has examined optimistic” for the virus, she mentioned in an e mail.
The affected person’s major symptom was conjunctivitis; the person is being handled with an antiviral drug and is recovering, in accordance with the Facilities for Illness Management and Prevention.
The Division of Agriculture introduced the primary circumstances in dairy cows final week. As of Monday night time, the virus had been confirmed in 11 herds throughout 4 states: Texas, Kansas, Michigan and New Mexico, the company mentioned. Cows in Idaho might also be contaminated.
The virus has been recognized as the identical model of H5N1, an influenza subtype, that’s circulating in North American birds.
The C.D.C. is working with state well being departments to watch different individuals who might have been in touch with contaminated birds and animals, the company mentioned on Monday. It additionally urged folks to keep away from publicity to sick or useless birds and animals, and to uncooked milk, feces or different doubtlessly contaminated supplies.
That is solely the second case of H5N1 hen flu in folks in america; the primary was in 2022. The chance to most of the people stays low, specialists mentioned. However testing and evaluation is ongoing, and there are lots of unanswered questions.
“This can be a quickly evolving state of affairs,” the usD.A. mentioned in its announcement final week.
Right here’s what to know:
What’s hen flu?
Fowl flu, or avian influenza, is a bunch of flu viruses which are primarily tailored to birds. The actual virus in these new circumstances, known as H5N1, was first recognized in 1996 in geese in China, and in folks in Hong Kong in 1997.
In 2020, a brand new, extremely pathogenic type of H5N1 emerged in Europe and unfold rapidly world wide. In america, it has affected greater than 82 million farmed birds, the worst hen flu outbreak in U.S. historical past.
For the reason that virus was first recognized, sporadic circumstances have been present in folks in different nations. However a overwhelming majority resulted from extended, direct contact with birds.
H5N1 doesn’t but appear to have tailored to unfold effectively amongst folks, specialists say.
How did cows get hen flu?
Cows weren’t regarded as a species at excessive danger.
“The truth that they’re inclined — the virus can replicate, could make them sick — that’s one thing I wouldn’t have predicted,” mentioned Richard Webby, an influenza virologist at St. Jude Kids’s Analysis Hospital.
However this yr, experiences of sick cows started to emerge in Texas and New Mexico. Lifeless birds had been additionally discovered on a few of these farms, and laboratory testing confirmed that some cows had been contaminated with hen flu.
There are a number of ways in which the virus may need discovered its method into cattle. The doubtless route, a number of specialists mentioned, is that contaminated wild birds, which shed the virus of their feces, saliva and different secretions, contaminated the cows’ meals or water.
However different free-ranging animals recognized to be inclined to the virus, akin to cats and raccoons, might even have introduced the virus onto dairy farms.
How have cows been affected?
Though the virus is usually deadly in birds, it seems to be inflicting comparatively gentle sickness in cows.
“It’s not killing animals, they usually appear to be recovering,” mentioned Dr. Joe Armstrong, a veterinarian and cattle manufacturing knowledgeable on the College of Minnesota Extension. Final week, the usD.A. mentioned that there have been no plans to “depopulate,” or kill, affected herds, which is the usual process when poultry flocks are contaminated with the virus.
The illness is primarily affecting older cows, which have developed signs that embrace a lack of urge for food, a low-grade fever and a big drop in milk manufacturing. The milk that the cows do produce is usually “thick and discolored,” in accordance with Texas officers. The virus has additionally been present in unpasteurized milk samples collected from sick cows.
It isn’t but clear whether or not the hen flu virus is the only reason for all of the signs and sicknesses which were reported, specialists cautioned.
How widespread is the issue?
It’s unclear. As of Monday, the usD.A.’s Nationwide Veterinary Providers Laboratory had confirmed hen flu infections in seven herds in Texas, two in Kansas, one in Michigan and one in New Mexico, the company mentioned.
Preliminary testing has prompt that an extra herd in Idaho might also have the virus, however that has not but been confirmed by the nationwide laboratory. Up to now, the virus has been discovered solely in dairy cows and never in beef cattle.
However as a result of cows aren’t routinely examined for hen flu, and the sickness has been comparatively gentle, there may very well be different contaminated herds which have escaped detection, specialists mentioned.
And the motion of cattle between states might transport the virus to new areas. The affected dairy in Michigan had just lately imported cows from an contaminated herd in Texas. When the cows had been transported, the animals weren’t displaying any signs. The farm in Idaho had additionally just lately imported cows from an affected state, Idaho officers mentioned.
How is it spreading?
That could be a key, and nonetheless unanswered, query. It’s doable that the contaminated cows are choosing up the virus independently, particularly if shared meals or water sources have been contaminated.
A extra worrisome chance, nonetheless, is that the virus is spreading from cow to cow. On Friday, the usD.A. famous that “transmission between cattle can’t be dominated out.”
A number of scientists mentioned that they’d be shocked if there weren’t a point of cow-to-cow transmission. “How else might it transfer so quickly?” mentioned Dr. Gregory Grey, an infectious illness epidemiologist on the College of Texas Medical Department.
If the virus can unfold simply between cows, that would result in bigger, extra sustained outbreaks. It could additionally give the virus extra alternatives to adapt to its new mammalian hosts, growing the danger that it acquires mutations that make it extra harmful to folks.
How will officers know if hen flu adapts to unfold between folks?
Analyzing the genetic sequence of the virus from contaminated birds, cows and other people can reveal whether or not H5N1 has acquired mutations that assist it unfold amongst folks.
Scientists have been carefully monitoring infections in birds and sea mammals and, now, cows. Up to now, the virus doesn’t appear to have the power to unfold effectively between folks.
In 2012, scientists confirmed that H5N1 was capable of unfold via air between ferrets — a well-liked mannequin for finding out transmission of respiratory viruses amongst folks — after buying 5 mutations.
A pattern of hen flu remoted from a Chilean man final yr had two mutations that point out adaptation to infecting mammals. However these mutations have beforehand been seen with out the virus evolving additional to unfold between folks, specialists mentioned.
Is it secure to devour dairy merchandise?
Federal officers have pressured that commercially processed milk stays secure to drink. Dairies are required to maintain milk from sick animals out of the human meals provide, and milk offered throughout state strains have to be pasteurized, a course of wherein the milk is heated to kill potential pathogens. Pasteurization “has regularly confirmed to inactivate micro organism and viruses, like influenza, in milk,” the Meals and Drug Administration mentioned in a brand new on-line information to exploit security.
Dr. Gail Hansen, a veterinary public well being knowledgeable and unbiased marketing consultant, agreed that the danger of being contaminated by pasteurized milk was most likely “very low.” She added, “I might not need folks to cease consuming milk due to it.”
However the chance couldn’t be solely dominated out, she mentioned, expressing some concern that federal officers had been “overconfident within the face of so many unknowns.” If cows are shedding virus into their milk earlier than they present indicators of sickness, that milk might doubtlessly discover its method into the business milk provide, she mentioned. And completely different pathogens might require completely different pasteurization temperatures and durations; the precise circumstances required to inactivate this specific virus remained unclear, Dr. Hansen mentioned.
The chance of being contaminated by the virus by consuming unpasteurized, or uncooked, dairy merchandise stays unknown, the F.D.A. mentioned. Uncooked milk is thought to pose quite a lot of potential illness dangers past avian influenza.
