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Yep, it's listeria bacteria. In normal healthy people it causes a mild, maybe even unnoticeable illness. "Infected pregnant women may experience only a mild, flu-like illness; however, infections during pregnancy can lead to miscarraige or stillbirth, premature delivery, or infection of the newborn." (CDC) There are 2500 serious cases per year in the US, including 500 deaths. About one third of the serious cases are in pregnant women, most of the rest are in immune compromised people.
There is *some* risk of listeria in any unpasteurized soft cheese (like some Brie), cold deli meat and hot dogs, or non-shelf-stable processed meats like smoked salmon and pate. You can also get it from raw meat, raw milk, even contaminated raw vegetables. However, it's my understanding that *most* cases are actually in Mexican immigrants who obtain soft cheeses from their home country that are contaminated.
So. After way too much info
I can tell you that with such a small risk (800 cases in pregnant women in the whole US) but such a large danger to the fetus, my comfort level is such that I might have a deli meat sandwich if nothing else will satisfy, or I might have some Brie for a special occasion, but on a daily basis I'd rather avoid that stuff than not.