Every so often, perhaps at 10 or more year intervals, the virus may undergo a major change and antibodies from previous infections or immunisation with vaccine will be totally ineffective. The virus is usually named from the year and location of the laboratory where it is first isolated. The great influenza pandemic of 1918-1919 was [...]

Pain is the usual obvious symptom. It is initially rather vague, centred around the umbilicus (navel), usually intermittent in character and associated with nausea, vomiting and loss of appetite. Anorexia or loss of appetite is a constant feature and characteristic of this condition. There may be either diarrhoea or constipation. If the inflammation progresses and [...]