BROOKLYN (PIX11) — Cases of a foodborne illness increased in Brooklyn in the last month, a health official said Wednesday.

Authorities do not yet know the cause of the increase in campylobacteriosis cases, a Department of Health and Mental Hygiene spokesperson said. The spokesperson did not specify where in Brooklyn the cases were.

There have been around 50 cases of campylobacteriosis infections in the borough since the start of October. It’s an increase in the past month compared to the rest of the year.

There are around 1.5 million cases of campylobacteriosis in the United States every year, according to the Centers for Disease Control and Prevention. Many more cases go either undiagnosed or unreported.

People can get it by eating undercooked or raw poultry. They can also be infected by eating something that touched undercooked or raw poultry.

Most people recover from campylobacteriosis on their own, according to the CDC. It can cause bloody diarrhea, fever, and stomach cramps. There can also be vomiting and nausea. Campylobacteriosis can cause a life-threatening infection in people with weakened immune systems.