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

Bird flu continues to look to airs a "low consequence to nan wide public" for now, nan Centers for Disease Control and Prevention says. But nan 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 nan agency were yet incapable to entree a Texas dairy workplace wherever a quality was infected pinch nan microorganism successful March, they disclosed successful attachments to nan report published Friday by nan New England Journal of Medicine. That prevented investigators from being capable to analyse really workers mightiness person been exposed to nan microorganism connected nan farm. 

That is because nan dairy worker who came to a Texas section agency for testing "did not disclose nan sanction of their workplace," said Lara Anton, a spokesperson for nan Texas Department of State Health Services. 

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

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

H5N1 was apt spreading done dairy farms via nan precocious concentrations of nan microorganism recovered successful nan 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 nan microorganism successful chaotic birds, a circumstantial "clade" of nan microorganism that scientists telephone 2.3.4.4b, appears to person enabled vertebrate flu to jump into cows. Multiple herds were apt infected during that first spillover earlier nan birds migrated north, officials person said.

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

Experiments tally by nan Food and Drug Administration show that pasteurized milk remains safe to drink, contempt traces of nan 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 really nan microorganism has dispersed successful different mammals infected by nan virus, which person mostly resulted successful what USDA scientists called "dead extremity hosts."

A fistful of variants pinch perchance worrying mutations person besides since been spotted successful cows, nan USDA study found. If those variants go dominant, it could alteration nan illness caused by H5N1 aliases make dispersed to different animals aliases 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 nan nonstop origins of nan microorganism that infected nan Texas dairy worker. While nan H5N1 series from nan quality lawsuit is intimately related to those recovered successful dairy herds, nan agency's study recovered it besides differs successful immoderate cardinal ways.

Those familial differences propose nan quality was infected by "an early, somewhat different virus" that was circulating successful cows earlier nan existent cases, aliases that aggregate spillovers whitethorn person really occurred. 

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

The quality worker has since recovered aft their vertebrate flu infection. They only developed conjunctivitis, aliases pinkish eye, without fever aliases different communal flu symptoms. The worker and their contacts were fixed oseltamivir, an antiviral curen 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," nan 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 aliases conjunctivitis are true, said Anton connected April 30.

But astatine slightest immoderate of those workers pinch 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 location were different group pinch symptoms who did not want to beryllium tested truthful we cannot opportunity pinch absolute certainty that nary 1 other contracted H5N1. We tin opportunity for judge that location were group sick pinch different respiratory viruses moving connected dairy farms," Anton said successful a statement..

With wellness authorities and experts limited connected dairy workers and their contacts volunteering for monitoring their symptoms and getting tested, those search nan 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 emergency room trends successful nan area were declining astatine nan aforesaid time. They hypothesized dumping of discarded from dairy farms pinch 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 aliases different animals, for immoderate different trends successful flu-like illness, flu, aliases conjunctivitis. CDC flu surveillance systems astatine this clip show nary indicators of different flu activity successful people," Dr. Demetre Daskalakis, head of nan CDC's National Center for Immunization and Respiratory Diseases, told reporters Wednesday.