Causative agent
Polioviruses types 1, 2 and 3 (wild type)
Clinical description
Poliomyelitis is an acute infection caused by any of the three wild
type polioviruses. Over 90% of infections are asymptomatic. The remainder
of infections result in clinical illness, which can range from non-specific
febrile illness (5% of infections), aseptic meningitis (1% of infections)
to flaccid paralysis (<1% of infections). The risk of paralytic poliomyelitis
varies with age, rising from approximately 1 in 1000 infections in infancy
to up to 1 in 10 infections for adults. Paralysis is more likely to
affect the legs than the arms, but can involve all four limbs. Recovery
may be complete or only partial and post-polio syndrome, a deterioration
of the originally affected muscles has been reported to occur 30-50
years later in many patients. If the paralysis also affects muscles
for breathing and swallowing, poliovirus infection is life threatening
.
Transmission
Primarily person-to-person transmission through the faecal-oral route.
The incubation period is usually 7- 14 days for paralytic cases, but
with a reported range of 3 - 35 days. An infected person may transmit
virus in throat secretions for 3 - 10 days after exposure and in the
faeces for up to 6 weeks, but is most infectious in the few days before
and after onset of symptoms. As humans are the only reservoir of infection,
eradication, through vaccination is possible.
Surveillance in Scotland
- Statutory notification of poliomyelitis
- Laboratory reports for wildtype polio virus
Definition for surveillance Notification
Any person with:
- acute onset of a flaccid paralysis of one or more limbs with decreased
or absent tendon reflexes in the affected limbs, without other apparent
cause, and without sensory or cognitive loss
(Centers for Disease Control and Prevention)
Laboratory report
Laboratory reports for wild type polio virus (as opposed to live attenuated
oral polio vaccine virus)
Incidence
There have been no cases of indigenous wild type polio in the UK for
over 15 years now. The last notification of polio in Scotland was in
1994, and was vaccine-associated paralytic poliomyelitis, rather than
derived from wild type virus. The patient had been
in close contact with a recent recipient of oral polio vaccine. The
European Region of the World Health Organisation was certified polio-free
in June 2002, having been free of indigenous polio for over three years.
However, poliovirus imported from polio-endemic countries remains a
threat.
Poliomyelitis Notifications and Vaccine Uptake
Scotland 2000-2009
Year |
Vaccine Uptake* (%) |
Notifications (all ages) |
2000 |
97.6 |
0 |
2001 |
97.5 |
0 |
2002 |
97.3 |
0 |
2003 |
97.6 |
0 |
2004 |
97.6 |
0 |
2005 |
97.5 |
0 |
2006 |
97.9 |
0 |
2007 |
97.9 |
0 |
2008 |
98.1 |
0 |
2009 |
98.3 |
0 |
* Uptake rates by 24 months |
Prevention
Polio vaccination was introduced in the UK in 1956, in the wake of
dramatic paralytic poliomyelitis epidemics. Inactivated polio vaccine
(IPV) is included in the UK Childhood Immunisation schedule, with routine
primary vaccination recommended at 2, 3 and 4 months, and booster doses
at 3-5 years and 13-18 years. This replaces oral polio vaccine which
was used until September 2004.
Further Information
Vaccine Uptake
This can be found on the Information Services Division (ISD) website:
Notifications of infectious diseases
The Global Polio Eradication Initiative
Last reviewed: 14 December 2010
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