Which bacteria can cause severe gastrointestinal illnesses with symptoms including fever and bloody diarrhea?

The correct choice in this context is a bacterium known for causing severe gastrointestinal illnesses that often lead to symptoms such as fever and bloody diarrhea. Campylobacter is widely recognized as one of the leading causes of bacterial food poisoning and is frequently associated with the consumption of undercooked poultry or contaminated water. Symptoms typically manifest within a few days after exposure, manifesting as abdominal cramping, fever, diarrhea (which may be bloody), and sometimes vomiting.

Each of the other pathogens, while they may also cause gastrointestinal distress, have different profiles: Norovirus is a leading cause of viral gastroenteritis and typically leads to symptoms like nausea, vomiting, diarrhea, and abdominal pain but does not usually cause fever or bloody diarrhea. Shigella can cause bloody diarrhea, but its primary symptoms often include severe diarrhea accompanied by mucus and pus, and it may not commonly cause a fever. E. coli O157:H7, another bacteria implicated in foodborne illness, is also known for causing bloody diarrhea and can lead to severe complications, but it isn’t the bacterium indicated in this particular context when considering the most common association with fever. Therefore, Campylobacter is the most appropriate choice listed for causing the symptoms in question.