MadSci Network: Medicine

Re: helicobacter pylorii, where do we get it from?

Area: Medicine
Posted By: David Ng, PhD Student,School of Pharmacy and Medical Sciences
Date: Mon May 12 06:06:52 1997
Area of science: Medicine
ID: 862700353.Me
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!


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: 

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