[afro-nets] Open Learning Web site on Enteric pathogens

[Salvatore Rubino <rubino@uniss.it>]

Open Learning Web site on Enteric pathogens
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Dear Friends of the Open Learning Web site on Enteric pathogens

A new lecture is available at site
http://www.oloep.org/

Epidemiology of Helicobacter pylori Infection

Maria Pina Dore, Alberto Murino, Salvatore Fiori
Istituto di Clinica Medica, Sassari, Italy, Baylor College of
Medicine, Houston, TX, USA

Helicobacter pylori is a gram-negative, microaerophilic,
oxidase-, catalase- and urease-positive bacterium, motile by
means of a tuft of sheathed flagella at one pole. The bacterium
colonizes gastric mucosa and induces a strong inflammatory
response with release of various bacterial and host-dependent
cytotoxic substances. H. pylori infection is invariably
associated with gastric inflammation (gastritis) and has been
etiologically linked to several benign, premalignant, and
malignant lesions of the digestive system including acute
gastritis, peptic ulcers, atrophic gastritis, intestinal
metaplasia, gastric adenomas, adenocarcinomas and gastric
lymphomas of the mucosa associated lymphoid tissue. Humans are
the primary reservoir for the infection and the majority of H.
pylori infections are acquired early in life probably related to
close contact with the parents, especially the mother, and from
other children. The most common modes of transmission are
thought to be gastric-oral, oral-oral, and fecal-oral. There is
also evidence that in some developing countries, transmission
via contaminated food or water may be involved in primary
infections in children and in of reinfection among adults. In
specific setting, transmission from environmental or zoonotic
reservoirs could be important. Generally, the prevalence of the
infection is inversely related to household hygiene and general
sanitation.

H. pylori has been cultured from stool and has been identified
in feces by PCR. H. pylori can survive in coccoid forms for
several days suggesting that vehicles such as milk, water,
vegetable contaminated with H. pylori-containing feces are
potentially infectious to humans. Iatrogenic infection has been
documented following the use of a variety of inadequately
disinfected gastric devices, endoscopes, and endoscopic
accessories. In addition, gastroenterologists and nurses appear
to be at increased risk for acquiring H. pylori; this is
presumably due to occupational exposure to infected gastric
secretions. Universal precautions, standardized equipment
disinfection, and use of video-endoscopes which remove the
instrument channel away from the mouth, improvements in the
standards of living, including sanitation and central supplies
of clean water, should reduce H. pylori transmission. The fact
that the chain of transmission of the infection could be so
easily broken and the break is associated with improved
standards of living and general health of a population is
consistent with H. pylori always being a pathogen and never a
commensal or offering any significant benefit to the human host.

Ciao, Salvatore Rubino

--
Prof. Salvatore Rubino
Dip. di Scienze Biomediche
V.le San Pietro 43/b 07100 Sassari (Italy)
Tel: +39-079-228-302
Fax: +39-079-212-345
Cell:+39-3383865292
mailto:rubino@uniss.it