Not less than one individual in Texas has been identified with fowl 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 the US.
To this point, there are not any indicators that the virus has developed in ways in which would assist it unfold extra simply amongst folks, federal officers have mentioned.
The affected person’s major symptom was conjunctivitis; the person is being handled with an antiviral drug and is recovering, based on 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 some days later, in an extra herd in Michigan. Preliminary testing means that cows in New Mexico and Idaho can 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 probably contaminated supplies.
That is solely the second case of H5N1 fowl flu in folks in the US; the primary was in 2022. The danger to most people stays low, consultants mentioned. However testing and evaluation is ongoing, and there are a lot of unanswered questions.
“This can be a quickly evolving scenario,” the usD.A. mentioned in its announcement final week.
Right here’s what to know:
What’s fowl flu?
Hen flu, or avian influenza, is a bunch of flu viruses which can be primarily tailored to birds. The actual virus in these new instances, referred to 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 the US, it has affected greater than 82 million farmed birds, the worst fowl flu outbreak in U.S. historical past.
For the reason that virus was first recognized, sporadic instances 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, consultants say.
How did cows get fowl flu?
Cows weren’t considered a species at excessive threat.
“The truth that they’re prone — 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 12 months, stories of sick cows started to emerge in Texas and New Mexico. Lifeless birds have been additionally discovered on a few of these farms, and laboratory testing confirmed that some cows have been contaminated with fowl flu.
There are a selection of ways in which the virus might 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 identified to be prone to the virus, comparable to cats and raccoons, might 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, and so they appear to be recovering,” mentioned Dr. Joe Armstrong, a veterinarian and cattle manufacturing skilled 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 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,” based on 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 fowl flu virus is the only explanation 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 usD.A.’s Nationwide Veterinary Providers Laboratory had confirmed fowl flu infections in two herds in Texas, two herds in Kansas and one herd in Michigan.
Preliminary testing has steered that extra herds in Texas, New Mexico and Idaho can also have the virus, however these findings haven’t but been confirmed by the nationwide laboratory. To this point, 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 fowl 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 might transport the virus to new places. The affected dairy in Michigan had just lately 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 just lately imported cows from an affected state, Idaho officers mentioned.
How is it spreading?
That may 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 risk, 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 might 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 might result in bigger, extra sustained outbreaks. It will 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 fowl 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 intently monitoring infections in birds and sea mammals and, now, cows. To this point, 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 fowl flu remoted from a Chilean man final 12 months 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, consultants mentioned.
Is it protected to devour dairy merchandise?
Federal officers have burdened 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 bought throughout state strains have to be pasteurized, a course of during which the milk is heated to kill potential pathogens. Pasteurization “has frequently 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 skilled 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 risk 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 probably discover its method into the industrial milk provide, she mentioned. And totally different pathogens might require totally different pasteurization temperatures and durations; the particular situations required to inactivate this explicit virus remained unclear, Dr. Hansen mentioned.
The danger of being contaminated by the virus by consuming unpasteurized, or uncooked, dairy merchandise stays unknown, the F.D.A. mentioned. Uncooked milk is understood to pose quite a lot of potential illness dangers past avian influenza.
