ARI SHAPIRO, HOST:
The bird flu outbreak in U.S. dairy cattle keeps getting worse. More than 50 human cases have been confirmed, and the number of infected cows keeps growing too. That's why this week, the U.S. Department of Agriculture is beginning widespread testing of the nation's milk supply for the virus. NPR's Pien Huang is here to help us understand what's going on, Hey, Pien.
PIEN HUANG, BYLINE: Hey, Ari.
SHAPIRO: Tell us about this new testing program. How does it work?
HUANG: OK. So starting this week, the USDA is requiring samples of milk to be collected before it gets pasteurized and shared for testing. These milk samples are going to be taken from big storage tanks at dairy processing plants where milk from several different farms, tens of thousands of cows, are all mixed together. And while there are some in public health that say it's not really the robust testing they were hoping for, Ted McKinney, head of the National Association of State Departments of Agriculture, says it's a start.
TED MCKINNEY: Our sense is that, no, it's not going to every single milk tank on every single farm. But boy, it's the next best thing. It starts to get you more information, more surveillance data than you have now.
HUANG: Now, if a milk sample tests positive for bird flu, it's supposed to trigger a farm investigation to figure out where the cows are infected. This federal order starts with six states this week, including some states where it's spreading rapidly and states where no cases have been found. And it is intended to reach all 50 states in the future.
SHAPIRO: We've known about bird flu in cows for a while now. So why is this program launching now?
HUANG: Yeah, we have, Ari. And McKinney says that the idea of testing more robustly has been kicking around for a couple of months. State veterinarians, in particular, have been calling for more surveillance. But he says that it took some time to get everyone involved to agree on a plan.
The timing also does make it clear that this bird flu outbreak is not dying down. So remember, this is an outbreak that's thought to have started when bird flu jumped from wild birds to dairy cows in Texas sometime late last year. And in the spring, it became clear that it was spreading with cows that are being moved to different farms in different states. Since then, it has been detected in almost 850 herds in 16 states. And in the past few weeks in particular, it's been spreading rapidly among California's dairy cows. There have been more than 300 new confirmed cases in the past 30 days, and it's also infecting farm workers too.
SHAPIRO: Yeah. So tell us more about the numbers among humans. What do we know?
HUANG: Yeah. So according to CDC, there have been 60 confirmed cases in humans since April. Most of these have been in farm workers, though, there have been a few confusing cases with no known connection to farms or farm animals. Many of these have been mild. People have had flu symptoms, some eye infections. But there is some evidence that there are cases that are going unnoticed. You know, the CDC did a study of dairy farm workers and found that 7% had antibodies to bird flu, which indicated that they had recently recovered from it, maybe without even knowing that they had it. Seema Lakdawala at Emory University studies how flus spread.
SEEMA LAKDAWALA: Every time this virus spills over into humans, it has the potential to adapt and gain the properties necessary for transmission human to human.
SHAPIRO: That sounds ominous, Pien. So how worried should people be?
HUANG: OK, so on the one hand, Ari, it is good news that the version of the virus that's currently spreading among dairy cows has been spreading for almost a year now or more, and it hasn't been spreading a lot among humans or causing severe illness. The CDC does say that the risk of infection to the general public remains low.
But on the other hand, there was this recent study from the Scripps Research Institute that found it would take just one mutation to a viral protein to make it better infect humans. So not a pandemic yet. Everyone hopes it will stay that way, but people who track pandemics are worried.
SHAPIRO: That is NPR's Pien Huang with the latest on the H1N1 bird flu outbreak among dairy cattle and humans. Thank you, Pien.
HUANG: Thank you, Ari.
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