NEW DELHI: India has reported its first case of vaccine derived polio virus (VDPV) infection of 2012. A five-month-old child from the Murshidabad district of West Bengal has got infected with the virus after taking the oral polio vaccine.
This, however, does not threaten India’s recently awarded polio free status because though detecting VDPV is part of the surveillance system, it does not get added when putting together a country’s polio numbers.
Only infections caused by wild polio virus strains like P1 and P3 get counted. “The infected child is from Lalbagh block of Murshidabad district. Detailed follow-up investigations are being carried out. Preliminary reports indicate that the child was admitted to a hospital recently and has been ill for prolonged periods indicating the possibility of immunodeficiency,” a ministry official told TOI.
Oral polio vaccines (OPV) contain a weakened version of poliovirus, activating an immune response in the body. A vaccinated person transmits the weakened virus to others, who also develop antibodies to polio, ultimately stopping transmission of poliovirus in a community. According to experts, in very rare instances, the virus in the vaccine can mutate into a form that can paralyze — this is what is known as a VDPV.
In 2011, India reported seven cases of VDPVs — one of them in a child with congenital immune deficiency in Dhamtari district in Chhattisgarh — and the others in areas with low routine immunization coverage like Udaipur (Rajasthan), Ghaziabad and Badaun (Uttar Pradesh), Barnala (Punjab), Vidisha (Madhya Pradesh) and Jajpur (Orissa).
“None of the VDPVs detected in India during the past two years have shown evidence of circulation. None of the VDPV strains detected in India during 2010 and 2011 are genetically linked to each other. In response to the VDPV cases, state and district authorities have conducted catch up routine vaccination and localized polio vaccination campaigns,” India’s National Polio Surveillance Programme said.
Health ministry officials say importation of wild poliovirus remains the greatest threat to children in India.
Experts say OPV is a very safe and effective vaccine that has protected millions of children from paralysis. It was the bivalent polio vaccine that brought down India’s polio cases to zero. This is why last month, India was removed from the list of polio endemic countries after completing a full year without reporting a single case of wild polio virus infection.
According to WHO, from 2000 to 2010, more than 10 billion doses of OPV were administered to over 2.5 billion children. As a result, more than 3.5 million polio cases were prevented. During that time, 18 outbreaks of circulating VDPVs occurred in 16 countries, resulting in 510 VDPV cases.
“The small risk of VDPVs pales in significance to the tremendous public health benefits associated with OPV. Every year, hundreds of thousands of cases due to wild polio virus are prevented. Well over eight million cases have been averted since largescale administration of OPV began 20 years ago,” WHO said.
Circulating VDPVs in the past have been rapidly stopped with 2-3 rounds of high-quality immunization campaigns. The solution is the same for all polio outbreaks: immunize every child several times with the oral vaccine to stop polio transmission, regardless of the origin of the virus.
India’s achievement in stopping wild polio virus transmission is being considered one of the greatest achievements in public health in the 21st century. India’s last case of wild polio infection was reported on January 13, 2011, also from West Bengal.
Prime Minister Dr Manohan Singh said the real credit for this major achievement goes to the 23 lakh volunteers who repeatedly vaccinated children “even in the most remote areas, often in very bad weather conditions”.
India recorded 741 cases of polio in 2009 – nearly half the number of global cases. But in a remarkable turn of events, India reported just one case of the crippling disease in 2011 and went on to record zero cases in over 12 months since then.
On Monday, “a girl admitted to a hospital in West Bengal with polio-like symptoms sparked worries that India’s battle against polio may not be over yet,” the Wall Street Journal’s “India Real Time” blog reports, noting, “The suspected polio case … comes just two weeks after the WHO removed India from the list of countries where polio is endemic” (Stancati, 3/14). “‘It is a suspected case of polio. In medical parlance, the symptoms are called acute flaccid paralysis. The patient is under observation,’ Kumar Kanti Das, superintendent of Baruipur Subdivisional Hospital, [where the girl was admitted,] told the local Hindustan Times newspaper,” the Guardian writes (Burke, 3/13).
El Lunes, “una muchacha admitida a un hospital en Bengala Occidental con poliomielitis-como preocupaciones chispeadas síntomas que la batalla de la India contra poliomielitis puede no haber terminado todavía,” India de Wall Street Journal el blog la “que En Tiempo Real” señala, observando, “El caso sospechoso de la poliomielitis… viene apenas dos semanas después de la India quitada WHO del filete de países donde está endémica la poliomielitis” (Stancati, 3/14). ” “Es un caso sospechoso de la poliomielitis. En lenguaje médico, los síntomas se llaman parálisis flácida aguda. El paciente está bajo observación, “Kumar Kanti Das, superintendente del Hospital Subdivisional de Baruipur, [donde admitieron a la muchacha,] informó el periódico local de Hindustan Times,” el Guarda escribe (Burke, 3/13).
Nata Menabde, el representante del WHO a la India, “dice no hay pruebas a sugerir que el caso señalado allí es diferente de los áspero 8.000 casos de la parálisis flácida aguda que se han investigado en la India desde principios de año, ninguna cuyo está resultado ser poliomielitis,” el blog declara (3/14). “La administración de la salud del distrito ha cerco muestras del taburete del sospechoso y enviado les al laboratorio de la ministerio-corrida de la salud de la unión,” según Hindustan Times, que observa, el “WHO ha fijado un laboratorio nacional de la poliomielitis allí para probar las muestras de taburete de los sospechosos de la poliomielitis que venían de enfrente de los estados en la India del este” (3/13). Según Menabde, se prevee que los resultados “release/versión a finales de mes,” las notas del blog (3/14).
Paralytic polio returns to dent India’s pride
Paralytic polio – derived from oral polio vaccine (OPV) — used for vaccinating millions of children — has struck India to cripple a child in West Bengal within a week of the World Health Organisation (WHO) declaring the country free from the wild polio virus.
A case of vaccine derived polio virus (VDPV) type 2 has been confirmed in a five-month-old child in the Lalbagh block of Murshidabad district, reminding the health policy planner that the battle with polio is yet to be won.
However, there is a basic difference between the polio that struck the Bengal block and the virus that did not raise its ugly head in the country over the last one year. While the WHO recognition comes due to the effort to keep the country free from wild polio virus, the incident that occurred in West Bengal is a case of vaccine derived polio, which is rare but with the real danger of continuing with the oral polio vaccine for years without improving the overall immunisation scenario.
Even though the country was free from wild polio virus in 2011, there were seven cases of VDPV last year in Chhattishgarh, Rajasthan, Madhya Pradesh, Punjab, Orissa and Uttar Pradesh. While one child had congenital immune deficiency in Dhamtari district in Chhattisgarh, others lived in areas with low routine immunization coverage, according to the national polio surveillance being run by the Union Health Ministry and the WHO.
The classification, however, means little for the victims as both wild and vaccine-derived virus cause the same crippling paralysis in children.
In VDPV, the virus was derived from OPV due to prolonged intestinal infection and removal of certain beneficial genetic changes, veteran virologist T Jacob John said, adding that VDPV was similar to wild polio virus as it was neuro-virulent and could be transmitted easily.
It happens because OPV is made from live but weakened polio virus, a few which can come back as disease-causing agent. In India most of the VDPV cases are P-2 variety, which was eliminated from
the wild way back in 1999.
“Circulating VDPV is wild-like and if allowed to survive in humans, it will replace the niche vacated by wild viruses. So it is indeed a threat to eradication,” John who retired as professor at Christian Medical College in Vellore and advises the Union Health Ministry on polio told Deccan Herald.
The NPSP claimed that none of the VDPVs detected in India in the last two years showed evidence of circulation. None of the VDPV strains detected in India during 2010 and 2011 are genetically linked to each other.
VDPV is risk, long recognised in the OPV campaign. “VDPVs may already be in silent transmission. If so they will flare up into outbreaks, epidemics and exportation. So we must stop OPV but we cannot simply stop OPV. Its a Catch 22 situation,” John commented.