At least 10 people on Vancouver Island and the Lower Mainland became seriously ill after using contaminated cocaine, health officials said Thursday.

The patients suffered from bone marrow suppression and an abnormally low number of a type of white blood cell, a spokeswoman for the Ministry of Healthy Living and Sport said.

Health authorities began seeing the cases a few months ago, with the most recent one reported this month, the spokeswoman said.

Provincial health officer Dr. Perry Kendall said the people who came down with the conditions used powdered cocaine believed to be from the same batch sold in the province.

"The drug that is contaminating the cocaine is something called levamisole, … which suppresses the white cell count and makes them vulnerable to infections," Kendall said.

He said levamisole is an antibiotic used to rid animals of worms.

People who used powdered cocaine and became ill should see a doctor or street nurse, he said.

Symptoms include persistent fever and chills, swollen glands, sores in the mouth or around the anus, skin infections and pneumonia.