Etiology Of Diarrhea

Diarrhoea is usually caused by infections. Non-infectious causes such as laxative abuse, animal or vegetable toxins, mycotoxins and inflammatory intestinal diseases (Crohn’s disease, ulcerative colitis) are much less common. Sometimes diarrhoea is the result of preformed bacterial toxins, with the bacterium itself being no longer present or active. Examples include staphylococcal diarrhoea, the ingestion of Clostridium toxins after eating contaminated meat (pigbel) and Bacillus cereus toxins (contaminated rice, among other things). There are many causes.

The following list is not exhaustive:

• Preformed toxins: produced by Staphylococcus aureus, Bacillus cereus, etc.

• Viruses: Rota virus, Norwalk virus, Astrovirus, HIV, Noroviruses, …

• Bacteria: Salmonella, Shigella, Yersinia, some Escherichia coli, toxicogenic Vibrio cholerae, Campylobacter jejuni, toxicogenic Clostridium difficile

• Protozoa: Giardia, Entamoeba histolytica, Balantidium coli, microsporidia, various coccidia (Isospora belli, Cryptosporidia, Cyclospora, Sarcocystis). Sometimes by malaria as well!

• Worms: only in case of serious infections, e.g. Schistosoma mansoni, Capillaria philippinensis, Strongyloides stercoralis, Trichinella spiralis; rarely by other worms. Since worm infections are so common in the tropics, worm eggs are often found in the stools. However, there is not necessarily an aetiological connection.

It is not always important to discover the exact cause of an episode of diarrhoea: for example, it is important to distinguish between amoebic colitis and bacillary dysentery, but the difference between Rota virus and Norwalk virus enteritis is at present not clinically relevant in the tropics. Intestinal infections caused by protozoa occur everywhere, but they are more prevalent in tropical climates. The climate helps protozoa to survive in the outside world and poor hygiene promotes their transmission. Diarrhoea is often found together with a parasitic infection, but the causal connection must always be assessed critically. It is important to distinguish between infection and disease. Of the many protozoa that are found in faeces, only a few types are potentially pathogenic. Occasionally, Plasmodium falciparum and Leishmania donovani can cause digestive symptoms. The diarrhoea then displays no particular characteristics.

Category: Medical Subject Notes , Medicine Notes