Health authorities in Montreal have issued a public warning following the sudden death of an 18-year-old woman.

The woman died Saturday of a meningococcal infection. Friends say she had been feeling unwell, but fought through it to celebrate her birthday the previous night.

“She was complaining about the cold that she developed a week before, but we really didn’t think it was anything serious,” Victoria-Angel Tiano told CTV Montreal.

The birthday party ended when the woman, who had not been drinking, started vomiting. Her condition worsened from there, and she died Saturday afternoon.

Dr. Lavanya Narasiah of Montreal Public Health said the sudden decline in the woman’s condition seemed to be unusual.

“[It is] very rare that it would lead to a death before even getting a chance to be diagnosed and treated,” she told CTV Montreal.

Twelve people who were in close contact with the woman have been put on antibiotics as a precaution.