At the very least one particular person in Texas has been identified with chicken flu after having contact with dairy cows presumed to be contaminated, state officials said 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 lately, cows in the USA.
To this point, there aren’t any indicators that the virus has advanced in ways in which would assist it unfold extra simply amongst folks, federal officers have stated.
The affected person labored straight with sick dairy cows, stated Lara M. Anton, a spokeswoman for the Texas Division of State Well being Providers. “We have tested around a dozen symptomatic people who work at dairies, and only the one person has tested positive” for the virus, she stated in an e-mail.
The affected person’s main 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 first cases in dairy herds in Texas and Kansas final week, and a few 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 observe different individuals who might have been in touch with contaminated birds and animals, the company stated 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 chicken flu in folks in the USA; the first was in 2022. The danger to most people stays low, consultants stated. However testing and evaluation is ongoing, and there are lots of unanswered questions.
“This is a rapidly evolving situation,” the usD.A. stated in its announcement final week.
Right here’s what to know:
What’s chicken flu?
Chook flu, or avian influenza, is a gaggle 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 shortly around the globe. In the USA, it has affected more than 82 million farmed birds, the worst chicken 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, consultants say.
How did cows get chicken flu?
Cows weren’t regarded as a species at excessive threat.
“The fact that they are susceptible — the virus can replicate, can make them sick — that is something I wouldn’t have predicted,” stated Richard Webby, an influenza virologist at St. Jude Kids’s Analysis Hospital.
However this 12 months, studies of sick cows started to emerge in Texas and New Mexico. Useless birds had been additionally discovered on a few of these farms, and laboratory testing confirmed that some cows had been contaminated with chicken flu.
There are a selection of ways in which the virus may need discovered its means into cattle. The probably route, a number of consultants stated, 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, and they seem to be recovering,” stated Dr. Joe Armstrong, a veterinarian and cattle manufacturing professional on the College of Minnesota Extension. Final week, the usD.A. stated that there were 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,” according to Texas officials. The virus has additionally been present in unpasteurized milk samples collected from sick cows.
It’s not but clear whether or not the chicken flu virus is the only real 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 chicken flu infections in two herds in Texas, two herds in Kansas and one herd in Michigan.
Preliminary testing has instructed that further 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 aren’t routinely examined for chicken flu, and the sickness has been comparatively gentle, there might be different contaminated herds which have escaped detection, consultants stated.
And the motion of cattle between states may transport the virus to new places. The affected dairy in Michigan had 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 lately imported cows from an affected state, Idaho officials said.
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 cannot be ruled out.”
A number of scientists stated that they’d be shocked if there weren’t a point of cow-to-cow transmission. “How else could it move so rapidly?” stated 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 will 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 folks.
How will officers know if chicken flu adapts to unfold between folks?
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 folks.
Scientists have been carefully monitoring infections in birds and sea mammals and, now, cows. To this point, the virus doesn’t appear to have the flexibility to unfold effectively between folks.
In 2012, scientists confirmed that H5N1 was in a position to spread through air between ferrets — a well-liked mannequin for finding out transmission of respiratory viruses amongst folks — after buying 5 mutations.
A pattern of chicken flu isolated 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 stated.
Is it secure to eat dairy merchandise?
Federal officers have burdened 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 bought throughout state traces should be pasteurized, a course of through which the milk is heated to kill potential pathogens. Pasteurization “has continually proven to inactivate bacteria and viruses, like influenza, in milk,” the Meals and Drug Administration stated in a new online guide to milk safety.
Dr. Gail Hansen, a veterinary public well being professional and unbiased advisor, agreed that the chance of being contaminated by pasteurized milk was most likely “very low.” She added, “I would not want people to stop drinking milk because of it.”
However the risk couldn’t be completely dominated out, she stated, expressing some concern that federal officers had been “overconfident in 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 means into the business milk provide, she stated. And completely different pathogens might require completely different pasteurization temperatures and durations; the particular situations required to inactivate this explicit virus remained unclear, Dr. Hansen stated.
The danger of being contaminated by the virus by consuming unpasteurized, or uncooked, dairy merchandise stays unknown, the F.D.A. stated. Uncooked milk is understood to pose a wide range of potential illness dangers past avian influenza.
