Polio: the myths, and the real fear
Posted online: Tuesday, October 16, 2007 at 0000 hrs

By the year 2005, India was to have become polio-free. Two years down the
line, one of the country's most successful immunisation campaigns is
struggling to meet that goal. Not only old suspect areas but newer regions
are reporting cases. Recently, Capital Delhi reported a case carrying the
PV3 strain. Will India be able to eradicate polio? Are oral drops, which
changed the way the world fought the highly infectious disease by providing
an effective and cheap weapon against it, the answer? Or do we need to
switch to the more expensive and painful injectable option? TEENA THACKER
looks for answers:
What is polio?
Poliomyelitis is a highly infectious disease caused by the polio virus. It
invades the nervous system, and can cause paralysis or even death in a
matter of hours.
How is polio transmitted?
The polio virus (scientifically known as the wild poliovirus or WPV) enters
the body through water or food that has been contaminated with faecal
material from an infected person. The virus multiplies in the intestine.
From blood it may pass to the nerves of the brain stem and spinal cord. The
disease mainly affects children under five years.
Only humans can catch polio. The incubation period is three-five days for
minor illness and one-two weeks for paralytic symptoms. So a large number of
people may have had a minor dose of polio without really being aware of it.
The more severe the original flu-like illness, the more chance there is of
deterioration occurring later in life (fatigue & weakness).
What are the different strains of polio?
Paralytic polio can be caused by any of three closely related strains
(serotypes) of poliovirus - PV1 (poliovirus1), PV2 and PV3. PV1 is the most
virulent and produces the most severe paralysis. According to the Union
Ministry of Health and Family Welfare, one out of every 200 children in
India is infected with this virus.
People with PV2 are often first diagnosed as having meningitis and may have
gone into a coma, but often the paralysis is less severe. Those who have PV2
are more likely to have had encephalitic polio and possible coma. Damage to
the brain can lead to poor memory, problems in keeping awake or falling and
staying asleep. PV2 is a weaker virus and has been eradicated from India;
the last case was reported from Aligarh in 1999.
PV3 is more likely to be found where there are reports of sporadic cases,
not in epidemics. The rate of infection in PV3 is one in 1,000. This strain
had been confined to western Uttar Pradesh for the past two years but has
now spread to other districts of the state and also Bihar. Those who have
PV3 seem to be more prone to developing Chronic Fatigue or Parkinson's later
in life.
There are 12 other viruses that are closely related to polio and can cause
paralysis. If they had been discovered before polio vaccines stopped polio
they would probably have been recorded as other polio types. At present
there is no vaccine for the other types as everything is geared at
eliminating the three known polio strains. But people are still being
paralysed by these other strains, now called acute flaccid paralysis.
Is there a cure for polio?
No, there is no cure for polio. Polio can only be prevented by immunisation.
The oral polio vaccine (OPV) is a safe and effective protection. Given
multiple times, it protects a child for life. As for fear of side-effects,
OPV is one of the safest vaccines ever developed. It is so safe that it can
be given to sick children and newborns. It is believed to have saved
millions of children around the world from paralysis.
Is injectable vaccine an option?
OPV helps in mass immunisation in densely populated and unhygienic
conditions. Using OPV, all the countries in the world except India,
Pakistan, Afghanistan and Nigeria have eradicated polio.
But all polio-free countries over a period of time have switched over to IPV
(injectable polio vaccine). Unlike OPV, IPV gives individual protection to a
child against all polio viruses. Two years back the India Experts Advisory
Group suggested that the Government explore the possibility of using IPV in
high-risk districts of western UP to supplement OPV. But in a country like
India where wild virus is still in circulation, OPV is the best means to
provide mass immunity.
How many doses of OPV does a child need?
OPV needs to be administered multiple times to be effective. The number of
doses it takes to immunise a child depends entirely on his/her health and
nutritional status, and how many other viruses the child has been exposed
to. Children living in areas that are densely populated and with poor
hygiene need higher doses of OPV.
Given that every time a polio case is reported there are a flurry of
accusations against the immunisation drive, what needs to be realised is
that until a child is fully immunised, he/she is still at risk from polio.
So it's important to immunise each child under five during every round and
ensure that all are given the vaccine at the same time.
What is the track record of the polio immunisation drive in India?
The campaign has made tremendous progress. Before the launch of the global
programme in 1988, India had, on an average, two to four lakh cases every
year, which has now been reduced to a few hundred.
How many new cases have been reported?
This year, 281 cases of polio have been reported, with Uttar Pradesh leading
with 223, followed by Bihar 40, Andhra Pradesh 5, Uttarakhand 4, Haryana 3,
Maharashtra 2, and one each from Gujarat, Rajasthan, Delhi and Orissa.
Source: Union Ministry of Health and Family Welfare

editor@expressindia.com
Publication : IE; Section : National Network; Pg : 6; Date : 16/10/07
URL : http://www.indianexpress.com/story/228875.html