Asthma rates in U.S. children have quieted down after a decades-long increase, a government study found, and researchers are trying to pinpoint reasons that would explain the trend.

A possible plateau in childhood obesity rates and declines in air pollution are among factors that may have helped lower cases in kids, the 2001-13 study suggests. Overall, average asthma rates among kids 17 and younger increased slightly, then leveled off and declined by the study's end, when 8.3 percent of kids were affected.

Using Google to help track STDs

With sexually transmitted diseases on the rise, researchers at the University of Illinois at Chicago think they might have a powerful new weapon to fight their spread: Google searches.

The nation's leading search engine has quietly begun giving researchers access to its data troves to develop analytical models for tracking infectious diseases in real time or close to it. UIC is one of at least four academic institutions that have received access so far, along with the Centers for Disease Control and Prevention.

Researchers can mine Google data to identify searched phrases that spiked during upticks in a particular disease. Then, they measure the frequency of those searches in real time to estimate the number of emerging cases.

Rich, white and no vaccinations

The people most likely to refuse to have their children vaccinated tend to be white, well-educated and affluent, researchers report. A study published in the American Journal of Public Health used California state government data on "personal belief exemptions," or opting out of vaccinations for nonmedical reasons. From 2007 to 2013, the rate of such vaccine refusal doubled, to 3.06 percent.

Exemption percentages were generally higher in regions with higher income, higher levels of education and predominantly white populations. In private schools, 5.43 percent of children were exempt, compared with 2.88 percent in public schools.

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