As avian flu spreads among US cows—32 herds in 8 states—concern increases
The highly pathogenic avian influenza (H5N1) that is spreading among US dairy cows is causing concern for researchers worldwide as the virus is finding its way into new states and herds. According to a number of specialists, the United States is not disclosing enough genetic data derived from isolated viruses as part of the federal inquiry into the sudden and spreading outbreak.
Thirty-two infected herds in eight states (Idaho, Kansas, Michigan, New Mexico, North Carolina, Ohio, South Dakota, and Texas) have been counted by the US Department of Agriculture thus far. The virus may spread in certain situations due to cattle moving between herds. However, the USDA has not made it clear to the public whether the herds are connected in a single epidemic chain or whether there is proof that the virus has infected cows more than once. Early Texas infections were associated with dead wild birds (grackles, blackbirds, and pigeons) discovered on dairy farms. However, according to reports from Stat News, the USDA told them that not all of the diseases were connected to the instances in Texas.
According to the USDA, the virus is spreading through livestock movements, which suggests that cow-to-cow transmission is taking place. However, it is unknown how the virus is transferring throughout cows. Assuming that even the most sick cows exhibit minimal respiratory symptoms, the USDA surmises that contaminated milking equipment is the most likely means of transmission.
The New York Times on Friday revealed that the single herd of H5N1-infected cattle discovered in North Carolina had no symptoms, further raising doubts about the virus's potential to spread. This suggests that the virus may be quietly spreading among an undetermined number of additional asymptomatic herds and states. The USDA recommended testing for H5N1 in its most recent FAQ document if herds exhibit clinical symptoms like fever, lethargy, reduced milk output, and loose stools. However, the Times said that the organisation has started paying farms to examine cows that show no symptoms.
In the meantime, the USDA has stated that it had proof that
H5N1 from dairy farms has returned to infect birds in neighbouring poultry
farms; however, it is also unclear how this is occurring.
Data gaps
Concerns regarding the virus's evolving ability to infect mammals and its potential to infect people are raised by the lack of clarity and extensive transmission. The World Health Organization's head scientist, Jeremy Farrar, warned reporters in Geneva last week that the virus's spread among US dairy cows is "enormous concern," according to CNN. The main worry is that the virus may change and become capable of infecting humans as a result of spreading to ducks, chickens, and now more frequently, mammals. The capacity for transmission from person to person is then crucial."
Experts are also concerned that, as they do with neighbouring poultry farms, the infections from dairy cows may spread to adjoining pig farms. Pigs are potential breeding grounds for novel recombinant flu strains since they may contract both human and bird flu viruses.
The genetic sequences of the H5N1 viruses infecting cows, according to the USDA, have not yet shown any modifications that "would make it more transmissible to humans and between people." However, Stat last Thursday revealed that, among other things, international experts have criticised the USDA for not disclosing more genetic data from its investigation. The organisation had only released a small number of genetic sequences in an international database of viral genome sequences (GISAID) until this past weekend.
Head of the virology department at Erasmus Medical Centre in Rotterdam, the Netherlands, Marion Koopmans told Stat this week that "a country with capacity like the United States should be able to generate this information within days." "I would expect very fast, very transparent updates, and it’s somewhat amazing not to see that happening."
The USDA announced the release of 239 genetic sequences to GISAID on Sunday in the face of growing criticism. Adding raw data to a US federal database is being done, it said, "in the interest of public transparency and ensuring the scientific community has access to this information as quickly as possible." The organisation declared that it will keep providing this kind of data on a continual basis.
The head veterinary for the USDA, Dr. Rosemary Sifford, told
the Times, "Remember that we have only been working on this for a little
over a month. We are putting a lot of effort into producing more
information," she remarked.
In general, the US Centres for Disease Control and Prevention and the USDA
still believe that there is no risk to the general public. On the other hand,
safety measures are advised for farmworkers and anybody else who comes into
close contact with sick animals.
H5N1 is generally mild in cows and rarely or never causes
death, whereas it is devastating in birds. High amounts of virus are present in
sick animal milk, although the infection is being eradicated. The Food and Drug
Administration is certain that the virus would be eliminated during the
pasteurisation process, even in the unlikely event that some contaminated milk
finds its way into the supply. The FDA stated in a FAQ on Friday that
"pasteurisation has continually proven to inactivate bacteria and viruses,
like influenza, in milk." However, several experts have demanded facts to
support this.