Updated: Sun, 12 May 2013 13:43:59 GMT | By Maggie Fox, Senior Writer, NBC News

Bird flu: US safe from two new viruses - so far



Influenza A H7N9 as viewed through an electron microscope. Both filaments and spheres are observed in this photo.

Influenza A H7N9 as viewed through an electron microscope. Both filaments and spheres are observed in this photo.

More than 50 travelers just back in the United States from China who had flu-like symptoms have been tested for the H7N9 bird flu virus, federal health officials say. So far, none has tested positive.

But the fact that they’re being tested at all shows just how worried the U.S. government is about this new strain of bird flu, which threatens at the same time as a still-mysterious coronavirus from the Middle East. The test kits had to be specially made up and distributed under an emergency provision.

“While no cases of H7N9 have been detected at this time in the U.S., 54 people with flu-like symptoms after travel to China have been tested. All have 54 tested negative for H7N9; while six tested positive for seasonal influenza A, and three tested positive for seasonal influenza B,” the Centers for Disease Control and Prevention says in its latest update on the virus.

Emergency operations centers are running 24/7, keeping an eye on both situations. While it's not unusual for the centers to be operating around the clock, it is rare to have two pandemic threats at once to plan for, says Edward Gabriel, who heads preparedness and response issues at the health and Human Services Department. 

"We want the latest and best information that we can get," Gabriel told NBC News. "We also need to look and see where it is moving to. To try to isolate its motion is a pretty significant thing."

If either virus turns into a form that spreads easily from person to person, a pandemic could follow within weeks. Both seem especially deadly in their current form: H7N9 seems to have about a 20 percent fatality rate, while the new coronavirus appears to have killed more than half its victims.

“In the case of the two latest threats — the H7N9 influenza virus and the new coronavirus — the number of infected people is small, and the infections are occurring thousands of miles away from the United States. Yet we should be seriously concerned about both,” Mike Osterholm, an infectious disease expert at the University of Minnesota, wrote in the New York Times on Friday.

“Our public health tools to fight these viruses are limited. We have no vaccines or effective drugs readily available to stop or treat the new coronavirus in the Middle East,” Osterholm adds. 

The H7N9 flu can spread silently, as people transmit influenza before they’re sick themselves. If the flu did mutate into a pandemic form, it would probably take at least six months to make enough vaccines to protect large numbers of people.

“It may take longer than it takes the virus to spread,” says Dr. John Treanor, a flu vaccine expert at the University of Rochester Medical Center. “The technology that we have today is such that the bulk of the pandemic disease may have already taken place before a vaccine is in place and can be used,” he added.

“The virus can spread very, very quickly. You are in a race against time.”

That happened in 2009, when the new strain of H1N1 swine flu broke out to cause the first pandemic of a new flu in 40 years. Companies raced to make vaccine but it was months before it was ready.

There are drugs to fight flu – a pill called Tamiflu and an inhaled powder called Relenza. Neither is a cure, however, and both need to be given very quickly to do much good at all.

Right now, H7N9 seems mostly confined to China and the spread has slowed. The World Health Organization reports 32 people have died out of 131 lab-confirmed cases.

“The drop-off in newly reported H7N9 cases in China may be the result of containment measures reportedly taken by Chinese authorities, including closing live bird markets, a venue where the risk of exposure to bird flu viruses can be high," the CDC says. “However it may also be a result of changing seasons, or a combination of both.”

Researchers in Hong Kong did a computer analysis of the outbreak and estimate that at least 200-500 more people have likely been infected with H7N9. The virus seems to cause serious illness mostly in people over 65 – doctors are not sure why yet.

“We estimated that risk of serious illness after infection is 5.1 times higher in persons 65 years and older versus younger ages,” Ben Cowling and colleagues at Hong Kong University wrote in the journal Eurosurveillance.

The evidence suggests that most of the patients got infected directly by birds, probably in poultry markets. So Cowling’s team took all the data and estimated how many younger people were likely to have been infected without knowing they had H7N9. "Our results suggest that many unidentified mild influenza A(H7N9) infections may have occurred, with a lower bound of 210–550 infections to date," they wrote. This would mean the virus isn’t that widespread, but which also confirms its high fatality rate. 

The coronavirus, which some are dubbing Middle East Respiratory Syndrome Coronavirus, or MERS, is a little different story. WHO says 33 infections have been reported, with 18 deaths. Experts are watching cases in France, where one patient who traveled from Dubai was confirmed to have the virus. On Sunday, French officials announced a 2nd confirmed case of coronavirus -- the hospital roommate of the 65-year-old man who initially fell ill. Officials were relieved that three health care workers who cared for him and who got sick have tested negative for the virus.

Some reports suggest an outbreak in Saudi Arabia also affected people in the same hospital.

This worries Dr. Eric Toner of the Center for Health Security at the University of Pittsburgh Medical Center. SARS – severe acute respiratory syndrome – also spread mostly in hospitals. SARS spread to 29 countries in 2003, killing 775 people and making 8,000 sick before it was stopped.

“These cases, whether confirmed or not, should be a wake-up call,” Toner writes in his blog.

The good news is that SARS was stopped using good hospital hygiene. Face masks, gloves and careful disinfection prevented its spread. And SARS only spread once people were noticeably ill, unlike flu, which people can spread before they feel sick and after they feel better.

The bad news is that hospitals may have forgotten this lesson. “SARS was stopped by healthcare workers being aware of the disease, having a high index of suspicion of anyone with fever and respiratory symptoms who had recently been in an affected region, and quickly implementing infection control measures with any suspect case,” Toner says.

“Until now, all cases of MERS originated in the Middle East, but as the confirmed French case demonstrates, the virus is only a plane ride away from other parts of the world. In the 10 years since the SARS outbreak, many hospitals have become lax in their attention to respiratory precautions.”

Gabriel says he’s working to make sure this isn’t the case with U.S. hospitals. “Hygiene practices are now better than they ever have been,” Gabriel said. “We send out reminders daily.”

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