Polio is back in Punjab, with a five-month-old girl from a Barnala village the latest victim of the deadly virus. But this time, the disease was caused by a vaccine-derived poliovirus (VDPV) instead of a wild virus, making it the sixth such case in the country this year.
A month after she was born, Sukhmani Kaur's lower body began weakening, leading to paralysis and finally to her death on Thursday morning.
When the family got her examined in a local hospital a week ago, doctors diagnosed her with polio-like symptoms. District authorities informed state health officials. A World Health Organisation (WHO) team visited Ghunas village of Barnala district on Wednesday on a fact-finding mission.
"It is a confirmed vaccine-derived poliovirus case, and not a wild virus case," said Dr Gagan Sharma, WHO's surveillance medical officer.
"We have taken the stool samples of the close community members and the samples have been sent to the Central Research Institute, Kasauli and a Mumbai lab for further investigation." Dr Balwinder Singh, Punjab programme officer, immunisation, said five other cases of VDPV had been reported from Chhattisgarh, Rajasthan, Uttar Pradesh, Madhya Pradesh and Maharashtra this year.
"There is nothing to worry; it can be due to weak immune system of the child," he said. "But parents should make sure that their child is vaccinated in each round of (polio) immunisation." According to experts, vaccine-derived polioviruses can emerge on rare occasions in under-immunised populations when the attenuated virus contained in a vaccine mutates and recombines with other viruses to create a circulating vaccine-derived strain.
The WHO says the spread of VDPV indicates many children remain under-immunised. In 2009, a total of four cases of polio were reported in Punjab. Of these, two were from Ludhiana, and one each from Mohali and Jalandhar. But all these were wild poliovirus cases. Health authorities were alarmed when a polio case was reported in Jammu last year. But it was found that the patient had contracted the virus in Ludhiana.
Mutations and combinations
According to the WHO, a vaccine-derived poliovirus (VDPV) is a rare strain of poliovirus, genetically mutated from the strain contained in oral polio vaccine
The oral polio vaccine contains 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.
In very rare instances, the virus in the vaccine can mutate into a form that can cause paralysis. When this virus regains the ability to circulate,
it is called a circulating vaccine-derived poliovirus.