At the very least one individual in Texas has been identified 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 thousands and thousands of birds and sea mammals worldwide and, most not too long ago, cows in america.
Up to now, there are not any indicators that the virus has developed in ways in which would assist it unfold extra simply amongst individuals, federal officers have mentioned.
The affected person labored immediately with sick dairy cows, mentioned Lara M. Anton, a spokeswoman for the Texas Division of State Well being Providers. “We have now examined round a dozen symptomatic individuals who work at dairies, and solely the one individual has examined constructive” 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 keeping with the Facilities for Illness Management and Prevention.
The Division of Agriculture introduced the primary instances in dairy herds in Texas and Kansas final week, and a number of days later, in a further herd in Michigan. Preliminary testing means that cows in New Mexico and 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 individuals to keep away from publicity to sick or lifeless birds and animals, and to uncooked milk, feces or different doubtlessly contaminated supplies.
That is solely the second case of H5N1 hen flu in individuals in america; the first was in 2022. The chance to most of the people stays low, consultants mentioned. However testing and evaluation is ongoing, and there are numerous unanswered questions.
“It is a quickly evolving state of affairs,” the united statesD.A. mentioned in its announcement final week.
Right here’s what to know:
What’s hen flu?
Hen flu, or avian influenza, is a gaggle of flu viruses which are primarily tailored to birds. The actual virus in these new instances, known as H5N1, was first recognized in 1996 in geese in China, and in individuals in Hong Kong in 1997.
In 2020, a brand new, extremely pathogenic type of H5N1 emerged in Europe and unfold rapidly around the globe. In america, it has affected greater than 82 million farmed birds, the worst hen flu outbreak in U.S. historical past.
Because the virus was first recognized, sporadic instances have been present in individuals in different international locations. However a overwhelming majority resulted from extended, direct contact with birds.
H5N1 doesn’t but appear to have tailored to unfold effectively amongst individuals, consultants say.
How did cows get hen flu?
Cows weren’t considered a species at excessive threat.
“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 Youngsters’s Analysis Hospital.
However this yr, studies of sick cows started to emerge in Texas and New Mexico. Useless birds have been additionally discovered on a few of these farms, and laboratory testing confirmed that some cows have 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 consultants 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, reminiscent of cats and raccoons, may even have introduced the virus onto dairy farms.
How have cows been affected?
Though the virus is commonly 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 skilled on the College of Minnesota Extension. Final week, the united statesD.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 embody 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 commonly “thick and discolored,” in keeping 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 real reason for all of the signs and sicknesses which have been reported, consultants cautioned.
How widespread is the issue?
It’s unclear. As of final Friday, the united statesD.A.’s Nationwide Veterinary Providers Laboratory had confirmed hen flu infections in two herds in Texas, two herds in Kansas and one herd in Michigan.
Preliminary testing has prompt that further herds in Texas, New Mexico and Idaho might also have the virus, however these findings haven’t 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 are usually not routinely examined for hen flu, and the sickness has been comparatively gentle, there might be different contaminated herds which have escaped detection, consultants mentioned.
And the motion of cattle between states may transport the virus to new places. The affected dairy in Michigan had not too long ago imported cows from an contaminated herd in Texas. When the cows have been transported, the animals weren’t displaying any signs. The farm in Idaho had additionally not too long ago imported cows from an affected state, Idaho officers mentioned.
How is it spreading?
That could be a key, and nonetheless unanswered, query. It’s potential that the contaminated cows are selecting up the virus independently, particularly if shared meals or water sources have been contaminated.
A extra worrisome chance, nevertheless, is that the virus is spreading from cow to cow. On Friday, the united statesD.A. famous that “transmission between cattle can’t be dominated out.”
A number of scientists mentioned that they’d be stunned if there weren’t some extent of cow-to-cow transmission. “How else may 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 might result in bigger, extra sustained outbreaks. It could additionally give the virus extra alternatives to adapt to its new mammalian hosts, rising the chance that it acquires mutations that make it extra harmful to individuals.
How will officers know if hen flu adapts to unfold between individuals?
Analyzing the genetic sequence of the virus from contaminated birds, cows and folks can reveal whether or not H5N1 has acquired mutations that assist it unfold amongst individuals.
Scientists have been intently 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 individuals.
In 2012, scientists confirmed that H5N1 was in a position to unfold by air between ferrets — a preferred mannequin for learning transmission of respiratory viruses amongst individuals — 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 individuals, consultants mentioned.
Is it protected to devour dairy merchandise?
Federal officers have harassed that commercially processed milk stays protected to drink. Dairies are required to maintain milk from sick animals out of the human meals provide, and milk offered throughout state traces have to be pasteurized, a course of during which 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 new on-line information to take advantage of security.
Dr. Gail Hansen, a veterinary public well being skilled and unbiased marketing consultant, agreed that the chance of being contaminated by pasteurized milk was most likely “very low.” She added, “I might not need individuals to cease ingesting milk due to it.”
However the chance couldn’t be fully 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 may doubtlessly discover its method into the industrial milk provide, she mentioned. And completely different pathogens might require completely different pasteurization temperatures and durations; the precise situations required to inactivate this explicit 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 a wide range of potential illness dangers past avian influenza.
