E. coli causes
diarrhoea |
A
vaccine to prevent travellers from tummy trouble has produced
promising results in trials.
The vaccine, taken as a drink, is designed to protect against the
most common cause of diarrhoea - the bacterium enterotoxigenic E
coli.
However, the researchers, from St George's Hospital, London, warn
it could be five years before it is made widely available.
Tests showed the vaccine was safe, and able to stimulate an
immune response.
A single dose was enough to trigger significant activity in the
immune systems of half of the 36 volunteers who were given the
vaccine, called spi-VEC. After two doses, the figure rose to 70%.
Dr Steve Chatfield, chief scientific officer at Microscience, a
biotechnology which has worked on the vaccine, said servicemen and
women travelling abroad would be recruited to take part in future
tests.
New generation of drugs
He said: "The results exceeded our expectations and pave the way
for the development of a whole new generation of oral vaccines which
are safe, easy to administer and effective.
"A lot of the armed forces serve in areas where this (ETEC) is
endemic so this could be useful to help them carry on with their
duties."
He said it was also possible that the vaccine had the potential
to help protect people living in areas of high infection.
However, this would depend on how long the vaccine remained
effective once it had triggered an immune response, and how often
top ups would be needed.
At the moment the aim is that each jab will provide six months'
protection.
The vaccine is made from salmonella bacteria which have been made
harmless by the removal of key genes. Chemicals from ETEC are added
to this to stimulate an immune response.
Even though the vaccine itself is harmless, the immune system
recognises it as a threat, and mounts action to try to destroy it.
Professor Ron Behrens, of the London School of Hygiene and
Tropical Medicine, said research would be more valuable if it
concentrated on how to prevent diarrhoea occuring among people who
live in the developing world.
It is estimated that diarrhoea kills 500,000 a year world-wide.
In contrast, said Professor Behrens, most cases of travellers'
diarrhoea were in no way serious, and only lasted for one to two
days.
He said: "Diarrhoea is caused by well over 100 known pathogens,
so this vaccine will only be effective in a limited number of
cases."
A second vaccine for diarrhoea, known as Dukoral, is due to come
on to the market within the next year.
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