Symptoms include fever, headache, vomiting, abdominal pain, cramping , bloody stool with leukocytes. Acute reactive arthritis, or Guillain Barre syndrome may follow. C.fetus causes a pneumonitis also and is associated with perinatal sepsis. Both are associated with stillbirth. Bloody stools and dehydration are common.
Severe shigellosis can produce toxic dilatation and perforation of the colon.
In patients expressing HLA-B27, Reiter's syndrome may develop. Incidence is higher with clindamycin. May or may not be bloody stool. May have only watery, voluminous diarrhea, or may also have abdominal cramps, fever, and leukocytosis. Toxic megacolon is a complication , but course is highly variable.