From the FDA: https://www.fda.gov/food/buy-store-serve-safe-food/dangers-r...

Symptoms of foodborne illness usually include: Vomiting, diarrhea, and abdominal pain Flu-like symptoms such as fever, headache, and body ache

While most healthy people will recover from an illness caused by harmful germs in raw milk – or in foods made with raw milk – within a short time, some can develop symptoms that are chronic, severe, or even life-threatening. If you or someone you know becomes ill after consuming raw milk or products made from raw milk – or if you are pregnant and think you may have consumed contaminated raw milk or cheese – see a healthcare professional immediately.

The Dangers of Listeria and Pregnancy Pregnant women run a serious risk of becoming ill from the germ Listeria, which is often found in raw milk and can cause miscarriage, or illness, or death of the newborn baby. If you are pregnant, drinking raw milk — or eating foods made from raw milk — can harm your baby even if you don’t feel sick. Raw Milk and Serious Illness Symptoms and Advice

Also note that "often found in raw milk" is only kind of accurate. We've never detected lysteria on our dairy. Both our environmental swabs and raw milk cheese samples have always been negative.

We'd consider it a serious problem if we detected it anywhere (drains, door sills, etc).