CDC says bird flu viruses "pose pandemic potential," cites major knowledge gaps

5/3: CBS Morning News

5/3: CBS Morning News 20:13

Bird flu continues to look to airs a "low hazard to the wide public" for now, the Centers for Disease Control and Prevention says. But the agency's scientists ran into roadblocks investigating a quality lawsuit of this "pandemic potential" microorganism this year, they said successful a caller report.

Epidemiologists from the bureau were yet incapable to entree a Texas dairy workplace wherever a quality was infected with the microorganism successful March, they disclosed successful attachments to the report published Friday by the New England Journal of Medicine. That prevented investigators from being capable to analyse however workers mightiness person been exposed to the microorganism connected the farm. 

That is due to the fact that the dairy idiosyncratic who came to a Texas tract bureau for investigating "did not disclose the sanction of their workplace," said Lara Anton, a spokesperson for the Texas Department of State Health Services. 

They besides were incapable to cod follow-up samples from the dairy workplace idiosyncratic oregon their contacts, which could person revealed missed cases arsenic good arsenic tracking the microorganism and antibodies against it successful the assemblage aft an infection.

The idiosyncratic did not deterioration protective oculus goggles oregon a look disguise that could person protected them from the virus, the study said. The microorganism was apt transmitted done their contaminated hands oregon droplets of the microorganism from sick cows. 

H5N1 was apt spreading done dairy farms via the precocious concentrations of the microorganism recovered successful the raw milk of infected cows, authorities said previously. 

The microorganism had been circulating successful cows for an estimated 4 months earlier it was confirmed by labs connected March 25, according to a draft report from U.S. Department of Agriculture scientists released Thursday.

A mutation to the microorganism successful chaotic birds, a circumstantial "clade" of the microorganism that scientists telephone 2.3.4.4b, appears to person enabled vertebrate flu to leap into cows. Multiple herds were apt infected during that archetypal spillover earlier the birds migrated north, officials person said.

Since then, astatine slightest 9 states person detected cattle infections from the virus. Cows mostly retrieve from H5N1, dissimilar the wide die-offs seen successful different species. Some herds with infected cows person besides remained asymptomatic and are continuing to nutrient milk.

Experiments tally by the Food and Drug Administration amusement that pasteurized milk remains harmless to drink, contempt traces of the microorganism recovered successful samples from market stores. The outbreak has besides prompted a renewed informing not to portion earthy milk, which has been linked to deaths of different animals like cats. 

The ongoing outbreak is besides successful stark opposition to however the microorganism has dispersed successful different mammals infected by the virus, which person mostly resulted successful what USDA scientists called "dead extremity hosts."

A fistful of variants with perchance worrying mutations person besides since been spotted successful cows, the USDA investigation found. If those variants go dominant, it could alteration the illness caused by H5N1 oregon marque dispersed to different animals oregon humans much likely.

The microorganism from cows has besides been spotted spreading retired of dairy farms into adjacent chaotic birds and poultry, apt ferried by contaminated beverage droplets and surfaces.

Questions besides stay astir the nonstop origins of the microorganism that infected the Texas dairy worker. While the H5N1 series from the quality lawsuit is intimately related to those recovered successful dairy herds, the agency's investigation recovered it besides differs successful immoderate cardinal ways.

Those familial differences suggest the quality was infected by "an early, somewhat antithetic virus" that was circulating successful cows earlier the existent cases, oregon that aggregate spillovers whitethorn person really occurred. 

While sequences collected from sick cows connected the worker's dairy workplace could person helped CDC scientists reply those questions, samples were "not disposable for analysis."

The quality idiosyncratic has since recovered aft their vertebrate flu infection. They lone developed conjunctivitis, oregon pinkish eye, without fever oregon different communal flu symptoms. The idiosyncratic and their contacts were fixed oseltamivir, an antiviral attraction for vertebrate flu that could besides caput disconnected infections.

"While acute conjunctivitis is simply a clinically mild illness, HPAI A(H5N1) viruses, including those belonging to clade 2.3.4.4b, airs pandemic imaginable and person caused terrible respiratory  illness successful infected humans worldwide," the study co-authored by CDC scientists said.

Missed infections?

Reports by a local veterinarian that different workers connected Texas dairy farms had symptoms of flu oregon conjunctivitis are true, said Anton connected April 30.

But astatine slightest immoderate of those workers with symptoms were tested and turned retired to beryllium antagonistic for H5N1, wellness officials successful Texas arsenic good arsenic neighboring New Mexico told CBS News.

"It's apt determination were different radical with symptoms who did not privation to beryllium tested truthful we cannot accidental with implicit certainty that nary 1 other contracted H5N1. We tin accidental for definite that determination were radical sick with different respiratory viruses moving connected dairy farms," Anton said successful a statement..

With wellness authorities and experts babelike connected dairy workers and their contacts volunteering for monitoring their symptoms and getting tested, those tracking the microorganism person turned to different information sources to look for signs of undetected spread.

One draft study of wastewater samples successful a northwest Texas municipality recovered that signs of H5N1 person surged successful sewers, but besides that exigency country trends successful the country were declining astatine the aforesaid time. They hypothesized dumping of discarded from dairy farms with sick cows are to blame, not sick humans.

The CDC has besides pointed to emergency room information for reassuring worries astir undetected H5N1 cases.

"We proceed to show flu surveillance data, particularly successful areas wherever H5N1 viruses person been detected successful dairy cattle oregon different animals, for immoderate antithetic trends successful flu-like illness, flu, oregon conjunctivitis. CDC flu surveillance systems astatine this clip amusement nary indicators of antithetic flu enactment successful people," Dr. Demetre Daskalakis, manager of the CDC's National Center for Immunization and Respiratory Diseases, told reporters Wednesday.