|MadSci Network: Medicine|
Helicobacter pylori is a bacteria which colonises the human stomach. Essentially, it is believed that H pylori has always been present in humans and have co-evolved over 300 million years (1). H pylori (or its relative) is also found in other animals including primates, and carbohydrates on its surface are also found in human cells (1). The prevalence of the bacteria is highest in the developing world and increases proportionally with age (3). It is currently uncertain as to how the bacteria transmits between people, however there has been reports of transmission via contaminated endoscopes. Some studies also suggest that the faecal-oral route is not the primary route of transmission - H pylori is not normally found in human faeces (2). Thirty to fourty percent of the adult Australian population is colonised with H pylori (2), however less than 20 % of these people will ever develop symptoms from this infection (1). In addition, H pylori displays great genetic diversity and it is believed that certain strains of the bacteria may be more harmful than others eg. those containing the cagA gene (1). In developed countries where H pylori is less prevalent, it is not uncommon for a single strain of the bacteria to exist, whereas multiple strains co-exist more commonly in developing countries. Thus, the colonisation of a single strain may predispose the individual to overt disease whilst the precense of multiple strains may have allowed for “a more balanced interaction with the host” (1) - hope that made sense!! Hope this answers your question - otherwise e-mail me! Cheers, Dave 1. Blaser MJ. Not all Helicobacter pylori strains are created equal: should all be eliminated? Lancet 1997; 349: 1020-2. 2. Helicobacter pylori: guidelines for healthcare providers. Australian Gastroerontology Institute 1995. 3. Berkow R, ed. The Merck Manual 16th ed. Rahway: Merck, 1992: 764-5.
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