Vaping-related illnesses in the U.S. are still rising, though at a slightly slower pace.

Health officials of Thursday said there have been nearly 1,500 cases and at least 33 deaths in the mysterious outbreak.

The Centers for Disease Control and Prevention has been updating the case counts each week. The latest jump — 180 cases since last week — was the smallest increase since mid-September.

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The outbreak appears to have started in March. Symptoms of the illness include severe shortness of breath, fatigue and chest pain. Most who got sick said they vaped products containing THC, the marijuana ingredient that causes a high.

Overall, about 1 in 10 said they vaped only nicotine.