den Boer, a legionellosis specialist at the Regional Public Health Laboratory Kennemerland (The Netherlands). But other research downwind, in this case remaining An outbreak in Norway of legionhas placed Legionella bugs too within the compound, where workellosis, or Legionnaires’ disease, far from their source, he says, ers might inhale the bacteria. killed 10 people and made more including the epidemiological But Blatny and colleagues than 50 people sick in 2005. An studies of the outbreak in Norneeded to determine whether epidemiological study pegged the way. “The way to prove that this the captured bacteria were visource of the infectious Legionella person got Legionella from that able and infectious. They used bacteria to an air scrubber at a facility is the way that Janet did real-time polymerase chain reacwood-processing plant, about 10 it in her article: through kilometers away from air sampling,” den Boer where the outbreak took states. “If you have an place. The facility also outbreak, you should houses aeration ponds look in the vicinity of the that are known to harbor thing” that is suspected all sorts of microbes, some to be the source. of which may be Lloyd Larsen, a micropathogenicsincluding biologist at the U.S. Arstrains of Legionella my’s Life Sciences Test bacteria. Facility at Dugway ProvNow, research pubing Ground, says that the lished in ES&T (DOI researchers did not suffi10.1021/es800306m) revisciently validate their its the debate over how model. The experiment far Legionella can travel. failed “to demonstrate New modeling and meathe outside limits,” he surements taken at the site confirm that the bac- Researchers modeled how Legionella bacteria might be car- explains, by sampling beried by wind from aeration ponds at a wood-processing yond the predicted leteria can travel by air at facility in Norway. gionellae boundaries. least 200 meters (m) downThe monitoring techwind of the ponds; howtion and other techniques to exniques the team used are not ever, some controversy still exists. amine the bugs. But the groundbreaking, comments TorIn 2006, lead author Janetserotype of Legionella pneumobjo¨rn Tja¨rnhage of the Swedish Martha Blatny of the Norwegian phila trapped by the monitors Defence Research Agency. HowDefence Research Establishment, turned out not to be the type ever, the way the researchers with co-workers from the commost likely to cause infections. put together known technology pany Borregaard, the Norwegian Legionellae are ubiquitous in and modeling yielded useful reInstitute of Public Health, and life surface waters and are somesults, he says, and confirms that sciences company Telelab AS, times even found in groundwaair transport is possible. More modeled the wood-processing ter. But the most likely sources studies are needed, he adds, plant’s air space, using computaof human exposure are cooling particularly in different industional fluid dynamics and weather towers and water distribution tries that use such treatment data. They looked at wind flow systems (including showers and ponds. The team also needs to and other factors to figure out exair conditioners), in addition to compare the airborne strains actly where to place air monitors treatment ponds for industrial with those present in the ponds, at various heights and locations sites. The disease is passed not Tja¨rnhage comments. around the buildings to capture from person to person but only Airborne Legionella stays relaLegionella aloft. through direct inhalation of vitively close to home, den Boer The researchers found that able cells from the environment. says. “It is an old discussion they could accurately predict the Thousands of people get sick which we had in the 1980s and path of Legionella within the from legionellae every year, but 1990s,” he comments. “Legionelplant’s footprint, and their those most susceptible tend to la is a bacteria that needs wamonitors captured several differter,” and that’s hard to find be elderly or immune-comproent species, depending on kilometers away from its source. mised patients. weather conditions and each None of the sources of the bug monitor’s height. They also —NAOMI LUBICK can be ruled out, says Jeroen found that the bugs traveled 200 m BLATNY ET AL.
Tracking airborne Legionella downwind
7028 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / October 1, 2008
10.1021/es802167a
2008 American Chemical Society
Published on Web 08/20/2008
