Pathology of illness: Aeromonas spp. causes a broad spectrum of infections in humans, often in immunocompromised patients, but has not been definitively implicated as a significant cause of food-borne illness. A. hydrophila may cause gastroenteritis in healthy individuals or septicaemia in individuals with impaired immune systems or various malignancies. Two distinct types of gastroenteritis have been associated with A. hydrophila: a cholera-like illness with a watery (rice water) diarrhoea and a dysenteric illness characterised by loose stools containing blood and mucus.
Symptoms associated with Aeromonas-related gastroenteritis include diarrhoea, abdominal pain, nausea, chills and headache, dysentery-like illness and colitis. Symptoms usually occur within 24–48 hours of exposure and generally last from one to 7 days (Kirov 2003). On rare occasions the dysentery-like syndrome is severe and may last for several weeks (FDA 2003). All people are believed to be susceptible to gastroenteritis, although it is most frequently observed in very young children. People with impaired immune systems or underlying malignancy are susceptible to the more severe infections (FDA 2003).
Illness caused by A. hydrophila is thought to be mediated partly by production of several cytotoxins. Other virulence factors thought to be associated with colonisation of the intestine have not been conclusively identified.
