Diarrhoea is subjective, and can be defined as an increase in the volume, frequency or fluidity of stool relative to normal for the patient. Dysentery is diarrhoea with the presence of blood, mucous and protein in the stool, and often associated with signs and symptoms of systemic illness, e.g. fever, weight loss, anorexia, abdominal pain and dehydration.
Acute diarrhoea can be categorised into (a) osmotic; (b) secretory; (c) inflammatory and (d) dysmotility. With osmotic diarrhoea, fasting usually results in resolution of the diarrhoea, but with secretory diarrhoea fasting probably will make no difference.
Questions to ask:
A summary of epidemiologic questions:
Questions to ask all the time:
· Weight loss?
· Any recent changes to medications?
Non-infectious causes are responsible for about 15% of diarrhoea cases. They include:
Causes of infectious colitis:
(a) Campylobacter spp. Most common diagnosed cause of bacterial diarrhoea. Backpacker’s diarrhoea; contaminated food/water. Summer months. ~1wk duration. Very young children, and young adults. Prodrome of fever, headache, myalgia and abdominal cramps. Faecal WBCs and RBCs.
(b) Salmonella spp. Cafeteria/restaurant outbreaks, family gatherings. contaminated food/water (eggs/poultry). Summer months. Very young and very old. Prodrome of fever, headache, myalgia and abdominal cramps. Faecal WBCs (and RBCs, but not so much).
(c) Shigella spp. person to person spread; within families, day care. Sudden onset fever, headache, myalgia, abdominal pain. Faecal WBCs and RBCs
(d) Y. enterocolitica person to person and contaminated food/water. Fever, RLQ abdominal pain. Mimics appendicitis. Faecal WBCs and RBCs.
(e) V. parahaemolyticus raw/undercooked seafood. Sudden onset fever, headache and abdominal pain. Faecal WBCs and RBCs.
(f) EHEC 0157:H7 contaminated food/water, meat, outbreaks in institutions, day care. Fever, abdominal cramps, very bloody stools. Can be complicated by HUS and TTP. Faecal WBCs and RBCs.
(g) E.histolytica contaminated food/water, travel in developing countries. Sudden onset fever, abdominal cramps, bloody diarrhoea (amoebic dysentery). Faecal WBCs and RBCs.
(h) C. difficile after treatment with Abx (especially clindamycin) and antimotility agents, and especially in hospital setting. Fever, abdominal pain, bloody stools. Faecal WBCs and RBCs. Toxin destroys colonic mucosa.