PITTSBURGH - The Allegheny County Health Department is now investigating 13 cases of severe lung illnesses.
That's more than double the number from where cases stood on Tuesday.
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Local health leaders are working with the Pennsylvania Health Department and the Centers for Disease Control.
In the investigation, health leaders haven't pinpointed a single device, ingredient or additive, but they did find some patterns of vitamin E oil in the patients.
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Most of the patients also used vaping products that contained THC.
Doctors believe what's causing the illnesses is not a germ and are looking at all the chemicals in vape juice.
"The bottom line is this is a real phenomenon. Parents need to look out for your kids. Find out what they are doing. Educate them that this is dangerous," said Dr. David Persse with the Houston Public Health Authority.
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