The U.S. Centers for Disease Control and Prevention (CDC) this week sent four epidemiologists to Colorado to investigate a rash of illnesses and three deaths connected to the consumption of synthetic marijuana products.

At least 75 people there have fallen ill recently from smoking blends of synthetic marijuana, often marketed online under the names "Spice" and "Black Mamba," legal herbs laced with chemicals intended to mimic the active component of marijuana, delta-9 tetrahydrocannabinol (THC).

The investigators continue to work with state and local health officials to determine whether the illnesses are connected. “Several individuals were in intensive care, and three deaths are being investigated as possibly associated,” Dr. Tista Ghosh, Colorado’s interim chief medical officer, told reporters.

In one case, 26-year-old Samuel Alvarado Jr. began hallucinating after smoking a blend marketed as Strawberry, and was taken to the hospital by his parents. On Friday, Alvarado remained in a hospital inpatient bed, recovering from the episode, according to his father Samuel. “I really thought he was going to die on us,” the elder Alvarado told reporters. “He was just crazy.”

The University of Colorado Hospital, where Alvarado was taken, received five patients suffering the effects of synthetic marijuana during the latter part of the week, for a total of 50 in the past two weeks. A similar surge in illnesses related to synthetic marijuana has been seen in Denver hospitals.

Largely available online and at many retail locations, the synthetic marijuana blends are illegal under state and federal law, though Colorado and Washington recently legalized marijuana for recreational use. Typically distributed in small packages, the products carry no warnings and do not disclose ingredients. Colorado public health officials say they’ve seen periodic surges of illnesses related to the smoking blends.

"Don't wait for the results of this investigation,” Ghosh said. “If you have synthetic marijuana, stop using it and destroy it.”

Presently, Colorado is one of only two U.S. states to permit the recreational use of marijuana, whereby people ages 21 and older may possess personal stashes no greater than one ounce, for consumption in private settings.