Oct. 24 (UPI) -- The number of people who have died from a vaping-related lung injury has risen to 34, up one from last week, the Centers for Disease Control and Prevention said Thursday.
The number of confirmed and probable cases increased to 1,604 in 49 states, the District of Columbia and the U.S. Virgin Islands, according to to CDC data.
According to investigators with the the U.S. Food and Drug Administration, the evidence suggests a substance related to illicit THC-containing vapes is responsible for the majority of cases.
"The latest national and state findings suggest products containing THC, particularly those obtained off the street or from other informal sources (e.g. friends, family members, illicit dealers), are linked to most of the cases and play a major role in the outbreak," the CDC wrote on its web page.
More deaths are currently under investigation, according to the agency.
"Case counts continue to increase and new cases are being reported, which makes it more difficult to determine the cause or causes of this outbreak," the CDC wrote.
Due to the fluidity of the situation, the simple advice from national health agencies remains the same: cease all use of all vapes, including nicotine vapes, until the investigation is complete.
The latest data shows that the age range of patients widening, getting both younger and older, with the youngest patient reported at 13 years old and the oldest at 75. The median age of 1,358 patients for whom data was collected was 23, the CDC said.
The median age of deceased patients stands at 49 years and ranged from 17 to 75 years. The vast majority of affected patients, 73 percent, were male.
Among 849 patients surveyed before Oct. 15 about about their vaping behavior during the three months prior to treatment, 78 percent admitted to using both THC and nicotine products.
Another 31 percent said they had only used vape products containing THC. Ten percent of patients interviewed said they used only nicotine vapes, according to the CDC.
The FDA has yet to publicly identify any substance or substances solely responsible for the outbreak, but investigators are broadening their laboratory testing procedures to include screening for specific chemicals in biopsy and autopsy samples. Investigators have also begun testing aerosol emissions from vaping product samples.
Patients affected by the outbreak typically experience coughing, shortness of breath or chest pains. Some patients have reported experiences nausea, vomiting or diarrhea. Other symptoms include fatigue, fever or weight loss, the CDC said.
In response to the outbreak, state officials have enacted a variety of bans, ranging from limited to comprehensive in the products they affect.
Last week in Colorado, officials with the state's Marijuana Enforcement Division announced the likely ban of three ingredients in cannabis vaping, including polyethylene glycol or PEG, vitamin E acetate and medium chain triglycerides, or MCT oil, derived from coconut oil. If finalized, the ban would begin Jan. 1.
Meanwhile, in Massachusetts, Gov. Charlie Baker's emergency four-month ban on all vaping products, both nicotine and THC, remains in effect despite a court challenge.