Health experts have uncovered a case of a European man who is carrying
the polio virus but has not developed the disease - even though his immune
system is weak.
Doctors cannot explain why the man is not seriously ill and wonder if
the polio virus could be changing.
We are putting diseases and viruses under pressure like we have
never done before by such an enormous amount of international travel
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Professor John Oxford
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They say the case proves that there is no room for complacency over the
continuing need for vaccination programmes - even though the disease has
officially been eradicated in Europe.
Doctors stress the man they now call "Polio Man" is not a serious
health hazard.
However, he is key to understanding how to deal with what virologists
term "the end game" of polio vaccination programmes - when polio
vaccination programmes can be ended safely.
No paralysis
"Polio Man" is immunodeficient but doctors are extremely surprised that
he has not developed paralysis or any form of the disease.
Vaccination has been a great success
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Paralysis usually occurs in just one in 100 cases of polio infection
but it nearly always occurs when the person has a weakened immune system.
"Polio Man" shows that the polio virus may be changing and is no longer
following the usual path of infection.
If so, doctors are wondering if current vaccines are adequate to
control the disease.
The case shows that even though the disease appears to be beaten, it
could still be lurking undetected and ready to strike.
Further infections
Dr Philip Minor, head of virology at the UK National Institute for
Biological Standards and Control, thinks that the weakened form of the
virus that "Polio Man" originally received in the oral vaccine has somehow
mutated inside his body back into the full-strength natural virus.
He said: "Although there is no official record that anyone has caught
polio from him, it is a possibility.
"We find this a very interesting case. Unvaccinated children could be
at risk of contracting polio if their mothers have not passed on
antibodies onto their children.
"The man is not likely to be in contact with small children.
"But this is why vaccination programmes are important. People who are
vaccinated are not at risk."
The World Health Organization (WHO) officially stated on 21 June that
polio had been eradicated in Europe, following its eradication earlier in
the Americas and Western Pacific.
The disease is said to be eradicated when no cases are recorded for
three years.
However, health experts are debating how polio can remain eradicated
worldwide and when vaccination programmes can stop altogether.
Gastric problems
"Polio man" is in his late 20s, has never suffered from polio and was
vaccinated against the disease.
He is suffering from chronic immunodeficiency and chronic gut problems
such as diarrhoea which is common in such patients.
Doctors were alerted to his case in 1995 when conducting a study into
gastric problems associated with immunodeficiency.
One test during the study involved analysis of the man's faeces and
this revealed the presence of polio.
It appears he may have been excreting the live virus in his faeces for
over 20 years
The case is also very relevant in light of the continuing MMR debate
and how necessary vaccination programmes are to protect worldwide
populations from the disease.
John Oxford, Professor of Virology, St Bartholomew's and the Royal
London School of Medicine, London, UK, said: "Until the scientific
community sorts out infectious diseases and learns how to control them, we
cannot start thinking about more complicated advances in health.
"We are putting diseases and viruses under pressure like we have never
done before by such an enormous amount of international travel. These
diseases want to survive.
"No vaccine is safe, but it's a damn sight better than the real
disease," he said.
Professor Oxford also explained that recombinant diseases may become
more of a problem where diseases join to form a new disease combination by
swapping genes.
Dr Minor and his colleagues are currently writing a scientific paper on
the man, set for publication in a medical journal later this year.
