Crude methods of detecting swine flu have so far provoked hand-wringing and no small amount of ridicule. Planeloads of travelers to China have had laser beams aimed at their foreheads, landing some under quarantine (and spurring a YouTube minifest of airport videos). This summer, Slate reported on a camp that tried to prescreen kids for flu by checking campers for fevers—and failed to detect a sick child whose physician parent brought his temperature down with Tylenol, fueling an outbreak. Meanwhile, people infected with the virus can pass it on before they develop symptoms; others never develop fever at all.
With swine flu cases surging again in much of the United States, a portable and cheap detector that could ID the infected—even before they fall sick—would be a boon to public health. Despite some evidence that it gets deeper into the lungs than other seasonal viruses, most cases of swine flu are described as mild. But for people with asthma, diabetes, and heart disease; young children; and pregnant women, H1N1 can be grim. Even worse, some parents irrationally plan to avoid vaccination for their kids, and fears remain that a more virulent form may yet emerge—both of which could fuel trouble. Better methods of detection could make a big difference, especially in day care centers, hospitals, and schools, by pinpointing who should stay home and who might benefit from early treatment.
Happily, researchers are gaining ground with a novel strategy to detect a wide range of infections and assess their severity in individuals. Traditional detection efforts have focused on fishing for pathogens like viruses or bacteria, and this remains a critical approach. But a growing number of scientists are also zeroing in on the other side of the battle—the individual's immune response. The molecular signatures of that response may offer clues as to what ailment, exactly, a person has, how sick he may become, and what treatments could help him. It's like analyzing Napoleon's invasion of Russia by focusing on the Russians' scorched-earth retreat. It's a big idea, with possibilities extending well beyond flu season.
Scientists at Duke, for instance, are mapping broad biological changes, including immune-related changes, among students who are exposed to or come down with H1N1. The hope is that these signals will appear early enough and prove adequately specific to be used for early screening. The researchers first made strides looking at a range of respiratory infections. In September, they reported on combinations of genes that were expressed in response to cold virus, the respiratory syncytial virus, and seasonal influenza A: They exposed healthy (and willing) subjects to the virus and tracked them with repeated blood samples as some developed symptoms. Then they analyzed molecular changes in those blood samples, homing in on signatures that predicted who got sick. Using these signatures, they could distinguish viral infections from one another—as well as from bacterial infections—with signals appearing relatively early on. Now the group has turned to swine flu, which is on the rise at Duke, with several hundred cases so far this year.Students enrolled in the study are providing blood samples, e-mail check-ins, and, if they get sick, information on their close contacts, with whom researchers will also try to follow-up.
The goal is to develop a molecular signature for H1N1 and other viruses that could be used for early detection. The team also hopes to build a portable device that would search for disease with just a small amount of blood—or simply a nasal swab or saliva sample. Such an approach might help ID people who would benefit from fast antiviral treatment, those who should be isolated, and those who need not be—perhaps saving planeloads of irritation down the road. The Duke work is funded by the Defense Advanced Research Projects Agency, the central research and development office for the Department of Defense, which would also like to identify infected soldiers before they spread disease or are sent on assignments they might become too sick to perform. DARPA apparently sees parallels between students and soldiers, who live in crowded quarters, get little sleep, and endure intensive (if different) kinds of stress, lead researcher Geoff Ginsburg told me.