Sunday, November 19, 2006

Polio eradication failure

Slowly it is now being reported and acknowledged as well that polio eradication has been a failure in India. It is a shame that India is the only country other than Nigeria to have polio cases in triple digits while even very least developed countries like Kenya, Angola and Cameroon have only reported one case each this year so far. Countries like Somalia, Pakistan, Afghanistan, Namibia, Bangladesh, Ethiopia, Niger etc., have fared better than India in polio eradication. While the incidence of polio reportedly fell from 24,000 in 1988 to 4,800 in 1994 before the pulse-polio programme was started and it further fell to 66 cases in 2005, it rose to 522 in 2006 so far.

Polio is a virus that causes paralysis. The virus multiplies in the gut and is spread by contaminated water. Improvements in water and sanitation can control the disease.

The polio control programme was working well till 1998 when WHO and other international bodies came up with this grand pulse polio programme.

Pulse Polio is an immunization campaign established by the government of India in 1994 to eradicate polio (poliomyelitis) in India by vaccinating annually all children under age five against poliovirus. Every child receives a dose of Oral Polio Vaccine (OPV), a live, attenuated virus which colonises the gastrointestinal tract. This virus competitively inhibits the wild, disease-causing poliovirus. Not only does this prevent pernicious infection in the host, it precludes transmission of the wild poliovirus to other hosts. Since poliovirus cannot survive outside a host for more than two weeks, theoretically it would be eradicated, resulting in the eradication of poliomyelitis.

The campaign proved to be successful, or so it was thought and the incidence of poliomyelitis in India has decreased dramatically: India recorded 4,791 cases of polio in 1994; 2,489 in 1997; 1,600 in 2002; 225 in 2003; 135 in 2004 and 66 in 2005. Instead of seeing a reduction in 2006, this year till October 2006 it was shocking to know that there are 522 cases reported, mostly in Uttar Pradesh and Bihar.

The oral vaccine being used in India is of the ‘trivalent’ variety that seeks to create immunity against all the three kinds of polio virus. Research has revealed that this vaccine is less effective against ‘Type 1’ virus found in India especially UP. Experts also suggest that the high population density coupled with the poor sanitation prevalent there interfered with the action of the OPV, thereby lowering its efficacy. ‘Type 2’ virus is stated to have been eradicated throughout the world, leaving only ‘Type 1’ and ‘Type 3’ varieties to be tackled. Use of monovalent vaccines for tackling ‘Type 1’ and ‘Type 3’ proved to be efficient. The basic premises on which the GoI introduced the trivalent vaccines in the first place appeared to be wrong going by the increase in the number of vaccine induced polio cases – 1600 – noticed last year. The premises were:

  1. That just three doses of the oral vaccine would protect a child from polio;
  2. That the live but weakened viral strain used in the oral vaccine would spread to other children who had not been immunized and protect them too; and
  3. That the oral vaccine would induce strong immunity in the intestines and protect children from being infected.

The choice of OPV (Oral Polio Vaccine) was questioned well at the beginning itself by experts like Dr. Pushpa Bhargava, the present Vice Chairman of National Knowledge Commission. It is reported that the India Expert Advisory Group, the official body monitoring the polio eradication programme has recommended that two rounds of injectible polio vaccine (IPV) be administered to all children in Moradabad and J.P. Nagar districts of UP, where polio is prevalent.

While the experts can be relied on to identify which of the types of vaccines is most suitable for tackling polio in the present juncture, what is appalling is that we have not been able to improve the sanitation conditions in our most populous regions even after nearly six decades of independence! More so when the conditions are in a position to interfere with vaccination programmes. It is time the Governments both at the Centre and in UP woke up to the stark realities of polio non-eradication and act fast without much ado.

1 Comment:

groger said...

the scandal is now becoming apparrent with the incredible rises in non-polio afp being reported in India. In failure areas the rates have been as high as 22/100,000 ( Utter Pradesh and Bihar). Non-polio afp ( acute flaccid paralysis) is either being caused by Guillan Barre Syndrome ( as a result of the massive doses of oral polio vaccine being administered) or due to NPEV ( non polio enteric virus) infection. whatever the cause, it is a scandal that the GPEI run by the WHO isnt investigating the cause. some children are having up to 30 doses of OPV administered.