This case presents an additional concerning aspect to a worldwide pandemic that has decimated bird and marine animal populations, and has recently been observed in herds of cattle.
Following contact with dairy cows thought to be contaminated, at least one person in Texas has been diagnosed with bird flu, according to state officials’ announcement on Monday.
The revelation gives an alarming new facet to an outbreak that has impacted millions of birds and marine mammals globally, including cows in the US most recently.
According to government experts, there are currently no indications that the virus has changed in a way that would make it easier for people to contract it.
According to Lara M. Anton, a spokesman for the Texas Department of State Health Services, the patient had direct contact with sick dairy cows. She stated in an email that “we have tested about a dozen symptomatic people who work at dairies, and only one person has tested positive” for the virus.
Conjunctivitis was the patient’s main symptom; the Centers for Disease Control and Prevention report that the patient is responding to treatment with an antiviral medication.
Last Monday, the Department of Agriculture declared the first instances involving dairy cows. According to the FDA, as of Monday night, the virus had been identified in 11 herds located in four states: Texas, Kansas, Michigan, and New Mexico. Idaho cows could also be contaminated.
The virus is the same strain of the influenza subtype H5N1, which is now circulating in birds in North America.
The C.D.C. announced on Monday that it is monitoring further individuals who might have come into touch with animals or birds that are infected in collaboration with state health authorities. It also advised people to stay away from raw milk, excrement, and other potentially contaminated objects, as well as from ill or dead birds and animals.
There have only been two cases of H5N1 bird flu in the US; the first occurred in 2022. According to experts, there is still little risk to the general people. However, there are still a lot of unsolved concerns and ongoing study and testing.
In its release last week, the U.S.D.A. stated, “This is a rapidly evolving situation.”
Observe the following:
What is bird flu?
A class of influenza viruses known as “bird flu,” or “avian influenza,” is primarily adapted to infect birds. The specific virus responsible for these recent occurrences, known as H5N1, was discovered in Chinese geese in 1996 and in humans in Hong Kong in 1997.
A novel, extremely dangerous strain of H5N1 surfaced in Europe in 2020 and rapidly expanded globally. Over 82 million farmed birds have been impacted by the greatest bird flu pandemic in American history.
Infrequent incidences of the virus have been discovered in individuals in various nations since it was initially discovered. But the great majority came from long-term, up close interactions with birds.
H5N1 does not yet seem to have adapted to spread efficiently among people, experts say.
How did cows get bird flu?
It was not believed that cows were a highly vulnerable species.
Richard Webby, an influenza virologist at St. Jude Children’s Research Hospital, said, “I wouldn’t have predicted that they are susceptible—the virus can replicate, can make them sick.”
However, in Texas and New Mexico, reports of sick cows started to surface this year. On some of these farms, dead birds were also discovered, and laboratory examinations revealed that some of the cows had bird flu.
There are several possible routes by which the virus entered livestock. According to a number of scientists, the most likely scenario is that the cows’ food or water was polluted by infected wild birds, who spread the virus through their excrement, saliva, and other secretions.
However, the virus may have also entered dairy farms through other free-ranging animals like cats and raccoons that are known to be vulnerable to it.
How have cows been affected?
It seems that the virus is only mildly sickening cows, despite the fact that it frequently kills birds.
Dr. Joe Armstrong, a veterinarian and University of Minnesota Extension specialist in cattle production, stated that “it’s not killing animals, and they seem to be recovering.” The U.S.D.A. announced last week that there were no intentions to “depopulate,” or kill, the afflicted herds, as is customary when the virus infects flocks of chickens.
Older cows are the main victims of the disease; they have shown signs of low-grade fever, appetite loss, and a marked decrease in milk supply. According to Texas officials, the milk that the cows do produce is frequently “thick and discolored.” Additionally, unpasteurized milk samples taken from sick cows have been shown to have the virus.
Experts noted that it is still unclear if the avian flu virus is the only source of all the symptoms and illnesses that have been recorded.
How widespread is the problem?
It’s not clear. Seven herds in Texas, two in Kansas, one in Michigan, and one in New Mexico have confirmed bird flu illnesses as of Monday, according to the U.S.D.A.’s National Veterinary Services Laboratory.
The national laboratory has not yet confirmed that another herd in Idaho may also be infected with the virus, despite preliminary testing suggesting that they might be. Only dairy cows have tested positive for the virus thus far; beef animals have not.
However, scientists noted that since the disease has been relatively mild and cows are not routinely tested for bird flu, it’s possible that other affected herds have gone undetected.
Also, the virus may spread to other areas due to livestock transportation across states. Recently, cows from an infected herd in Texas were imported by the concerned dairy in Michigan. The cows were exhibiting no symptoms at the time of transportation. According to Idaho officials, the farm there had also just imported cows from a state that was impacted.
How is it spreading?
It’s an important question that hasn’t been answered yet. It is plausible that the afflicted cows are acquiring the virus on their own, particularly in the event that communal food or water supplies have been tainted.
However, the idea that the virus is moving from cow to cow is more concerning. The U.S.D.A. stated on Friday that it is “not possible to rule out transmission between cattle.”
A number of scientists expressed their surprise if cow-to-cow transmission did not occur to some extent. In what other way could it travel that quickly? stated Dr. Gregory Gray, a University of Texas Medical Branch epidemiologist specializing in infectious diseases.
More extensive and longer-lasting epidemics may result from the virus’s ease of transmission amongst cows. Additionally, it would increase the virus’s chances of adapting to its new mammalian hosts and raising the possibility that it would acquire mutations that would increase its threat level to humans.
How will officials know if bird flu adapts to spread between people?
The genetic sequence of the virus from infected humans, cows, and birds can be analyzed to see if H5N1 has developed any changes that facilitate human-to-human transmission.
Researchers have been monitoring diseases in birds, marine mammals, and now cows with great care. The virus does not appear to be able to propagate effectively between humans at this time.
In 2012, researchers demonstrated that H5N1 could transmit by air among ferrets, a common model used to study human respiratory virus transmission. This was possible due to the acquisition of five mutations.
Two changes found in a bird flu sample recovered from a man in Chile last year suggest that the virus has adapted to infect mammals. However, doctors noted that those changes have been observed before without the virus growing further to spread among individuals.
Is it safe to consume dairy products?
It is still safe to consume commercially pasteurized milk, according to federal regulators. It is mandatory for dairies to ensure that milk from sick animals is not consumed by humans. Additionally, milk that is sold across states needs to undergo pasteurization, which involves heating the milk to eliminate any possible pathogens. In a recent online reference on milk safety, the Food and Drug Administration stated that pasteurization “has continually proven to inactivate bacteria and viruses, like influenza, in milk.”
Independent consultant and veterinary public health specialist Dr. Gail Hansen concurred that the likelihood of contracting an infection from pasteurized milk was most likely “very low.” “I would not want people to stop drinking milk because of it,” she continued.
Although she expressed some concern that federal officials had been “overconfident in the face of so many unknowns,” she acknowledged that the possibility could not be completely ruled out. According to her, if cows are releasing viruses into their milk before they exhibit symptoms of sickness, that milk may end up in the commercial milk supply. Furthermore, different pathogens would need varied pasteurization times and temperatures; according to Dr. Hansen, it was still unknown what particular circumstances would be necessary to render this particular virus inactive.
The Food and Drug Administration stated that they were unsure of the risk of contracting the virus by eating unpasteurized or raw dairy products. Beyond avian influenza, raw milk is recognized to have a number of additional potential health hazards.