Gastroenteritis
Gastroenteritis causing diarrhoeal disease is a consequence of infection of the bowel by any one of a number of agents including viruses which exert their effects by a number of different mechanisms. Some bacteria, such as Staphylococcus aureus, contain a toxin which has a direct effect on the wall of the bowel, causing increased contraction which produces abdominal pain, vomiting and diarrhoea. Others, such as cholera, bind to the cells on the surface of the bowel and secrete a toxin that stimulates the cells to increase the production of water and salts. This can result in large volumes of watery diarrhoea which in severe cases can cause collapse and death. Another mechanism by which infectious agents cause diarrhoea is by invasion of the bowel wall, causing inflammation. This occurs in infection by organisms such as shigella, producing loose motions containing blood and pus. Other agents predominantly affect the large bowel (see the large intestine). While supportive therapy using rehydration mixtures containing appropriate salts and glucose may be all that is necessary, antibiotics may in some cases be required to eradicate infection. All these agents are spread by the faecal oral route - in other words poor sanitation and poor hygiene are responsible.
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