The Tennessee Department of Health is asking health-care providers across the state to report any cases of respiratory illness they suspect to be associated with vaping. According to the latest data from the Centers for Disease Control and Prevention, nearly 200 people across 22 states have been hospitalized after using electronic cigarettes.

State Epidemiologist Dr. Tim Jones with the Tennessee Department of Health said patients are showing signs of serious lung problems.

“And it’s essentially severe lung disease, i.e., shortness of breath, coughing, wheezing—something that we might see with really bad asthma or pneumonia,” Jones said.

He said most of the patients are adolescents and young adults. Last week, the Knox County Health Department reported a resident there was hospitalized with symptoms thought to be linked to e-cigarette use. At least one individual in Illinois has died of severe respiratory illness linked to vaping.

According to the CDC, many patients reported a gradual start to their breathing issues before being hospitalized.

In some cases, they’ve reported vomiting, diarrhea and fatigue. Jones said the type of electronic cigarette product used doesn’t seem to be a factor.

“It doesn’t appear to be associated with a particular brand or a particular maker,” he said.

Jones added medical experts are in the dark as to what’s causing the illness, which began cropping up in hospital rooms in late June.

“Right now, we’re seeing such a sudden increase that, clearly, there’s something new going on,” Jones said. “It hasn’t yet been specifically identified, but as soon as we know, we’ll let people know. But clearly something is different, and has been different in the last couple of months.”

Even though cases in different states appear to be similar, the CDC has said it’s still unclear whether they have a common cause or are entirely different ailments.