A record number of people, livestock and birds have been infected with bird flu this year, in a wave experts have called “staggering”.
And this week, the United States reported its first serious human case of H5N1, and California declared a state of emergency over the virus just hours later.
The CDC still says the virus poses a “low” threat to the public, adding that there is no evidence it has begun to spread from person to person.
But infectious disease experts are alarmed by the numbers and warn that the scale of cases and each infection outside of birds increases the risk of the virus acquiring mutations, allowing it to spread between people.
Dr. Marc Johnson, a virologist at the University of Missouri, said on
Overall, the figures show that since the virus was detected in the US in January 2022, more than 12,000 domestic and wild flocks have been infected.
After Although the virus spread to cows this year, it was diagnosed in 866 herds in 16 states, most in California and Colorado.
And this year, 61 human cases have been detected in nine states, the highest number of cases reported in the United States in at least two decades. Before the current outbreak, the last human case of bird flu occurred in 1997.
California has declared a state of emergency over the emerging bird flu pandemic (number of workers wearing protective suits). The above shows workers in Eden Valley, Minnesota, in 2015. They were responding to a bird flu outbreak at a poultry farm.
Almost all patients had direct contact with infected birds or livestock and suffered only mild symptoms, such as conjunctivitis or conjunctivitis.
However, the tide has begun to shift towards those who do not work with poultry or livestock.
In September, a Missouri patient became the first to become infected without direct exposure to infected animals. It is not clear how they became ill.
A California teenager who was not exposed to infected livestock became ill last month.
And the disease may be evolving to become more dangerous. A strain linked to wild birds has caused serious illness in humans, including a patient in Louisiana and a teenager in Canada, who was hospitalized for at least three weeks and needed help breathing.
There is no evidence that any of the patients transmitted the disease to other patients.
However, the virus has been detected in unpasteurized or “raw” milk, prompting the United States Department of Agriculture (USDA) to announce that all companies that handle raw milk will be required to share samples for testing if they so choose. they request.
Many experts, including officials at the World Health Organization, have criticized the US response to the outbreak.
Experts have described it as a pandemic that “unfolds in slow motion.” Until last month, almost all testing of livestock and people exposed to infected cows was voluntary.
Even now, mandatory testing is limited only to livestock moving across state lines.
Sporadic cases have also been reported in pigs, which has researchers concerned because these animals can contract human and bird flu strains, and could be “mixing vessels” for a new strain of the bird flu virus.
This map shows cases of the virus detected in wild mammals, such as red foxes and seals.
And infections have been recorded among 419 wild animals other than birds in the US since May 2022, including red foxes, skunks, seals and raccoons.
Experts warned that these animals can contract the virus after eating the carcasses of birds that had died from bird flu.
Surveillance of the virus in wastewater has also detected traces at 60 of the more than 250 sites monitored across the United States.
In California and Iowa, more than 80 percent of samples tested positive.
The United States already has a stockpile of about 20 million bird flu vaccines in its national arsenal, officials say, which are “well compatible” with the H5N1 virus.
It also has the capacity to quickly earn 100 million more if necessary. However, the Biden administration said earlier this month that it has no plans to authorize a vaccine.
Supplies of antivirals such as oseltamivir (Tamiflu), which was used to treat the last American bird flu patient in Louisiana, are also available.
Work is still underway to develop an avian flu vaccine for poultry and there is evidence to show that human antivirals would work just as well in sick cows.