Swine Flu: At Level 5—and in Need of More Rapid Diagnosis

With a flu pandemic imminent, it's important to know who's actually infected.


By Bernadine Healy, M.D.

At least eight countries around the globe now have confirmed cases (91 in the United States) of the never-before-seen strain of influenza virus that appears to have only recently jumped from swine to human in a small rural village in Mexico bordering a pig farm. It is so far suspected to have claimed some 160 lives and infected approximately 2,500 people, though only a small number have been confirmed by viral typing. Thanks to rapid genetic analysis, scientists from Mexico and Canada not only identified the microbe as a new strain of the H1N1 type of influenza in a matter of weeks but have shown that this is no ordinary form of influenza, which is typically a mild virus when it has circulated in people for a long time. That this novel strain of swine flu has been carried to so many countries by travelers and has shown signs of human-to-human transmission in Mexico and the United States has prompted the World Health Organization to elevate the risk for a global pandemic from where it had been, a stable 3, to a 4 earlier this week and, today, a 5. This denotes a "a strong signal that pandemic is imminent" if not inevitable, as one WHO official said. All countries should now activate their pandemic preparedness plans, the WHO cautions, emphasizing increased surveillance and early detection.

It is still way too early to tell how the swine flu pandemic threat will play out, since most of the cases have a Mexican connection, and most infections outside Mexico have been mild. And there's not a lot of evidence yet of rapid and sustained human-to-human transmission. So it's good to stay informed and heed public-health advice about sensible hygiene, but don't panic. Still, the wily ways of the new swine flu virus, which so quickly tripped off emergency public-health alerts, identify a big hole in our medical preparedness for fast-moving outbreaks: the ability to rapidly diagnosis the specifics of a pathogen-induced illness when a patient first seeks care. Despite many successes in developing gene-based technology that can quickly and precisely identify microbes in the air and in people since the anthrax hit after 9/11, we have not deployed microbe detection technology in doctors' offices and clinics, where such outbreaks—natural or nefarious—first show up.

Once the swine flu virus was identified several weeks ago and genetically typed, the critical information became available for public-health agencies to confirm cases of infection in their own sophisticated labs. But sending swabs to distant labs takes time and leaves squishy and sometimes unduly scary numbers of "suspected cases" floating around for days or longer, with the patients themselves in worried limbo. With the full genetic sequence of the virus known and online, private companies can now incorporate the viral signature into their existing rapid-detection technology, so this may change.

One company, CombiMatrix, has just announced that it has upgraded its existing influenza-detection system to be able to identify this new swine flu within a matter of a few hours with a high degree of accuracy. It uses gene-chip technology that can readily identify the swine influenza and distinguish it from other flu strains now in circulation. Other companies are developing tests. Better pathogen detection has been a goal of the Department of Homeland Security and the military, making kits for rapid assays at the local level entirely feasible.

Imagine what this will mean if implemented: When an individual first seeks care in a doctor's office or emergency room, the doctors will be able to tell immediately whether the patient has swine flu and additionally test any or all contacts of people who have become ill. This will benefit the patient immensely, and it will provide more targeted and appropriate use of antiviral agents such as Tamiflu—which is already in short supply in many pharmacies. Rapid confirmation of the new swine flu infection will help public-health officials provide more accurate information to their own communities and guide local actions such as isolation, quarantine, and the closing of schools or other facilities. Such community-based tools have never before been available for managing a pandemic or an outbreak that is so seriously threatening to become one. But whatever the detection technology, it must be fast, accurate, and inexpensive enough for wide deployment.

The number of cases of swine flu will continue to grow as more people even with the mildest of flu symptoms have their respiratory secretions tested. Identification is a critical step in microbe hunting, as is exposing the silent trek that influenza takes as it moves in waves from city to city, country to country, and continent to continent. We need to know more about the distinctive behavior of this particular virus, which seems to have newly emerged in human form from its animal reservoir.

Related: Consider 14 things you need to know to protect yourself, and how schools around the country are closing as a precaution.