Analysis: Bird Flu Is Spreading, But Testing of People is a Challenge .

The first step in combating any infectious disease outbreak is detection. Without widespread testing, health officials have little sense of who is infected, when to treat patients and how to monitor their close contacts.

In that sense, the bird flu outbreak plaguing the nation’s dairy farms is spreading virtually unobserved.

As of Monday, the virus had infected 157 herds in 13 states. But while officials have tested thousands of cows and are monitoring hundreds of farmworkers, only about 60 people have been tested for bird flu.

Officials do not have the authority to compel workers to get tested, and there is no way for workers to test themselves. In the current outbreak, just four dairy workers and five poultry workers have tested positive for H5N1, the bird flu virus, but experts believe that many more have been infected.

The Covid-19 pandemic and the mpox (formerly monkeypox) outbreak in 2022 revealed deep fissures in the U.S. approach to testing for emerging pathogens. Those failures prompted federal agencies to move toward policies that would allow rapid scaling of testing during an outbreak.

But progress has been sluggish, interviews with more than a dozen academic and government experts suggest.

“The timeline seems slow, given the number of infectious disease emergencies is clearly increasing,” said Dr. Jay Varma, the chief medical officer at SIGA Technologies and a member of a committee that evaluated lab operations at the Centers for Disease Control and Prevention.

Fumbles with testing set back the response to Covid in the crucial early weeks of the pandemic. The nation was slow to develop the rapid tests that for many became mainstays of pandemic life.

During the outbreak of mpox, federal officials already had a diagnostic test. But for many weeks, clinicians needed to order it from public health laboratories, which created painful delays in diagnosis.

It took the C.D.C. several weeks to engage with commercial labs to make mpox tests more widely available.

This time around, tests for bird flu are plentiful: There are 140,000 of them at public health labs, 750,000 additional tests available if needed, and another 1.2 million on the way.

Federal officials said that the number of tests at hand was more than adequate. But the tests that can pinpoint H5N1 are again available only at public health labs.

Most clinics have tests for influenza generally, but they must send samples to one of the labs or to the C.D.C. to confirm infection with bird flu in particular.

“It doesn’t matter how many tests you can do if they’re not in the right place,” said Jennifer Nuzzo, the director of the Pandemic Center at Brown University.

Federal officials have repeatedly said that H5N1’s risk to the general public is low. But the virus has adapted to new hosts at an alarming pace. It may yet mutate to spread among people, some experts have warned.

If that were to happen, the nation would need tests not just in public health labs, but in homes, schools, workplaces and wherever else people might need speedy answers.

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