Most common group of viruses responsible for diarrhoea. Particularly affects infants up to ~ age 2 (but not including neonates who seem to have temporary passive immunity).
Vomiting, diarrhoea and colicky pain are common symptoms which may last from a few days to several weeks. Severe infections can present with fever or prostration (or may rarely mimic enteric fever with 'rose spots').
Beware complications which include osteomyelitis, pneumonia, meningitis.
There are four types of Shigella, (Sh. dysenteriae, flexneri, boydii, sonnei) all of which cause dysentery. Sh.sonnei is the commonest in the developed world. Common symptoms are colicky pain, blood / mucus in stool, fever. Antibiotics may be of use to shorten both illness duration and carriage - use co-trimoxazole or amoxycillin.
C.jejuni produces fever, malaise and myalgia first, followed by bloody diarrhoea and colicky pain.
Erythromycin or ciprofloxacin will shorten illness duration but are reserved for severe or prolonged cases.
5) V. cholerae
Endemic in SE Asia and parts of Africa and S.America.
Produces profuse watery diarrhoea (rice-water stool).
Sequelae are dehydration, metabolic acidosis (due to loss of bicarbonate), hypokalaemia and hypovolaemic shock. Requires prompt rehydration with fluids and electrolytes. Tetracycline reduces the time for excretion and therefore reduces risk of transmission.
5 strains of E.coli :-
Causes acute diarrhoea with fever and abdo pain. May cause either mesenteric adenitis from lymph node involvement or terminal ileitis (-> RIF pain). Often patients develop reactive arthritis and/or erythema nodosum.
Illness lasts 1-3 weeks and tetracyclines may speed recovery.
8) Giardia lamblia
Infection is via cysts in contaminated drinking water (cysts are resistant to normal levels of chlorination).
Produces either light asymptomatic infections or severe diarrhoeal disease which may be acute lasting 7-10 days or chronic. The diarrhoea is not profuse but is evidenced by loose foul smelling motions once or twice a day. Abdominal discomfort, anorexia, nausea, alcohol intolerance and food-induced travel sickness are all possible symptoms. Heavy infestation can cause malabsorption.
Treatment - metranidazole/tinidazole relieve symptoms; mepacrine hydrochloride or quinacrine can also be used.
9) Entamoeba histolytica -> amoebic dysentery
Can mimic ulcerative colitis and is difficult to confirm, therefore a course of anti-amoebic treatment should be given before steroid therapy (which will exacerbate amoebiasis) or surgery in patients with apparent UC who have been in an area of high prevalence of amoebiasis.
Incubation periods are variable (few days - several months).
Symptoms always include pain and diarrhoea + blood + mucus; acute illness may involve fever and systemic features.
Complications include liver abscesses, intestinal strictures, large bowel ulceration (-> perforation and peritonitis) or amoeboma (RIF granulomatous mass containing amoebae).
Metranidazole is good for relieving symptoms and treating liver abscesses. Metranidazole-resistance may exist so try tinidazole if it fails. Diloxanide furoate is required to clear intestinal cysts from asymptomatic carriers.
Usually produces self-limiting D&V but may produce prolonged severe, watery diarrhoea esp. in immunosuppressed, malnourished or homosexuals with gay bowel syndrome (from faecal contamination after anal intercourse). Treatment with spiromycin may be helpful in severe cases.