Why did America get so high on fake weed this spring?

We’ve told you about the rise of flakka in South Florida, but another drug recently saw an insane surge, though it seems to have disappeared just as quickly: Spice.

A synthetic form of marijuana, Spice is derived from a lab-grown chemical called JWH (usually imported from China) that is mixed with acetone, sprayed onto a plant material like tobacco, and smoked. Bad trips can lead to delirium and your heart rate to spike.

Between January and May of this year, state poison control centers reported 3,572 calls related to synthetic cannabinoid use, a 229 percent increase from the 1,085 calls during the same period in 2014, according to a new report from the Centers for Disease Control (CDC).

The majority of these occurred in April and May, and no one knows why.

“The CDC is working with several states to look into that issue,” CDC epidemiologist Royal Law told Fusion of the spring spice Spike. The agency does know that the majority of cases involved males between the ages of 20 and 29.

The geography of the incidents can also tell us a bit more about the situation: The most reported cases came out of Mississippi, and in April authorities busted a lab in Jackson yielding $8 million-worth of the drug. Here’s the map, from the American Association of Poison Control Centers.

As the Clarion Ledger‘s Sarah Fowler reported in May, some of Mississippi’s outsized incidents are due to the fact that the state sent out a report to hospitals to notify state authorities of all suspected cases, something other states may not yet be doing.

Sam Owens of Mississippi’s Bureau of Narcotics told Fusion that one possible explanation is that Spice use itself didn’t increase but that a more potent or harmful variation may have started making the rounds, resulting in more hospital visits (this might also explain the drop-off in reported incidents).

“We’re still seeing it, but encounters at ERs are down, so it maybe a different batch,” he said.

If you smoked Spice around Easter time, please get in touch at [email protected].

Rob covers business, economics and the environment for Fusion. He previously worked at Business Insider. He grew up in Chicago.