Infectious diarrhoea

Infectious diarrhoea remains a major cause of morbidity and mortality worldwide. Viruses, bacteria and protozoa are responsible for the majority of infections, which are transmitted most commonly by the faecal–oral route through water, food and person-to-person transmission. Clinical presentation of infectious diarrhoea conforms to three patterns: acute watery diarrhoea; dysentery; and persistent diarrhoea, which can include steatorrhoea. Diagnosis still rests heavily on stool microscopy and culture, although faecal antigen tests and molecular assays are increasingly used. Oral rehydration therapy continues to be the most important supportive intervention, particularly in acute watery diarrhoea, in which death from dehydration and acidosis can be prevented in the vast majority of sufferers. There have been some important advances in the development of new approaches to antibiotic therapy. The non-absorbable antibiotic, rifaximin, is highly effective in the treatment of traveller's diarrhoea and has fewer adverse effects than systemically absorbed antibiotics. The broad-spectrum antimicrobial, nitazoxanide, is often effective in the treatment of cryptosporidiosis but is also effective in giardiasis, amoebiasis and Clostridium difficile infection. There is great interest currently in promicrobial therapies: probiotics, prebiotics and faecal microbial transplantation. Recent meta-analyses suggest that promicrobial therapies have a place in the prophylaxis and treatment of antibiotic-associated diarrhea, especially C. difficile infection, and acute diarrhoea in children.