A chequered past

Ancient Egyptian art depicts otherwise healthy people with withered limbs, and children walking with canes. It is also believed that the Roman Emperor Claudius was afflicted with the disease. Another famous sufferer was Sir Walter Scott, believed to be the earliest recorded case of the disease in the British isles. Several centuries later, the United States of America was struck by a polio epidemic in 1952. Of the nearly 58,000 cases reported that year, 3,145 died and 21,269 were left with mild to disabling paralysis.

In India, which has a relatively high incidence of the disease, the polio eradication programme launched in 1995 was expected to have perfect results by 2000. But although a remarkable decline in the incidence of polio was achieved, cases are still being reported, a majority from the states of Uttar Pradesh and Bihar.

Poliovirus Type 1 (P1)

Polio is a contagious disease caused by a virus that survives in the throat and intestinal tract. It has three strains, wild poliovirus type 1, wild poliovirus type 2 and wild poliovirus type 3. But of the three, the wild poliovirus type 1 is considered the most contagious. It spreads very fast and one out of every 200 children is infected with this type, say experts. In affected areas like Uttar Pradesh, multiple factors come into play in the spread of polio. “In the case of western Uttar Pradesh, its peculiar demography like high density of population and high birth rate causes the rapid growth of this type of virus,” said Dr Naveen Thacker, consultant paediatrician, Deep Hospital, Gandhidham, Bhuj, and former president of the Indian Academy of Paediatrics.

Signs and symptoms

Up to 95 per cent of kids infected with polio may show no symptoms. About 4 to 8 per cent get minor symptoms like fever, fatigue, nausea, headache, flu, stiffness in the neck and back, and pain in limbs — all symptoms which subside completely at times. Less than one per cent of polio cases result in permanent paralysis of the limbs. Of those paralysed, 5 to 10 per cent die when the paralysis strikes respiratory muscles. Incidentally, it is difficult to gauge the strain of virus without a laboratory examination of stools.

Treatment

Two vaccines are used throughout the world to combat polio. The first was developed by Jonas Salk, first tested in 1952, and announced to the world on April 12, 1955. The Salk vaccine, or Injectable Polio Vaccine (IPV), consists of a dose of dead poliovirus.

The vaccines used in India to combat the virus are:

• Zero Polio: The dose is given to a baby immediately after birth. It only gives initial immunity to the child.

• Monovalent vaccine: This vaccine is used to combat wild poliovirus types 1 and 3.

• Trivalent vaccine: It is used for all the three strains of the poliovirus.

• Injectable Polio Vaccine (IPV): Unlike Oral Polio Vaccine, which is used in mass immunisation campaigns, the IPV is a more potent method of preventing the disease.

So which measure is the most effective? “There are logistical problem associated with the IPV, although it is of great help,” says Dr Panna Choudhury, national president, Indian Academy of Paediatrics. “There are two ways of keeping a check on this virus. First, monovalent vaccine should be given in affected areas and for individual protection the injectable polio vaccine should be taken,” adds Dr Choudhury. On the other hand, Dr Saroja Balan, senior consultant, neonatology, Apollo Hospital, believes that it is equally important to increase awareness among people and improve sanitation standards. “The coverage of the immunisation should be increased manifold and ensure that the awareness campaign is heightened,” she says.

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But why does P1 virus attack even after repeated vaccination? How many doses should be administered? Due to the highly contagious nature of the disease, even before the child is vaccinated there are chances of him or her contracting polio, even though the symptoms may manifest at a later stage.

In many areas, there are high chances of kids not receiving the “zero polio” dose at the hospital immediately after birth. “Even 1 per cent of children missing the vaccination in Uttar Pradesh translates into more than 1,20,000 possible victims,” says Dr Thacker. “The effectiveness of the Oral Polio Vaccine is not very high in affected areas compared to the other parts of the country due to its high transmission power. But, in affected areas, around 15 doses are required to provide sufficient immunity,” adds Dr Choudhury.