Author: Aimee Cunningham / Source: Science News
A city itself influences the contours of its flu season – whether flu cases rise to a wintertime peak or plateau from fall to spring, new research suggests.
Flu cases generally peak in winter in certain areas of the United States because the air is drier. That dryness helps the flu virus survive longer once sneezed out of a sick person, for example, allowing the virus to potentially infect more people. But after analyzing data on flu cases reported from 2002 to 2008 in 603 U.S. cities, researchers have found that a city’s size and structure also play a role in shaping local flu epidemics.
Larger cities with higher levels of crowding were associated with a steady accumulation of cases throughout a flu season. Smaller cities with less crowding tended to have a flu season with a more intense surge in winter, researchers report in the Oct. 5 Science.
“Understanding how the size and structure of cities impacts disease spread may help us to predict and control epidemics,” study coauthor and population biologist Benjamin Dalziel of Oregon State University in Corvallis, Ore., said October 2 at a news conference.
Larger U.S. cities have flu seasons that are less intense, on average, meaning new cases are more spread out from fall to spring, while smaller cities’ seasons tend to be more intense, with a sharp spike in winter, as shown in the graph.
Overall, smaller cities with larger fluctuations in humidity from season to season (primarily on the East Coast) are associated with high-intensity flu seasons, as shown on the map.…
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