A case of vaccine-derived polio has been confirmed in a two-year-old child from Meghalaya’s Tikrikilla, reported The Hindu on Tuesday.
Earlier in the day, a senior official from the Union Health Ministry stated that this was not a case of wild polio but rather an infection that individuals with low immunity may contract.
The case has led officials in the West Garo Hills district to be on high alert.
The World Health Organization declared India polio-free in 2014. The last case of wild poliovirus in the country was reported in 2011.
The symptoms of poliovirus can include fatigue, fever, headache, vomiting, diarrhoea or constipation, sore throat, neck stiffness, pain or tingling sensations in the arms and legs, severe headaches, and sensitivity to light, also known as photophobia.
Chief Minister Conrad K Sangma said that the two-year-old exhibited symptoms of polio over a week ago and was diagnosed with acute flaccid paralysis at a hospital in Assam’s Goalpara.
Health officials in the state sent stool and other samples collected from the child to testing centres operated by the Indian Council of Medical Research's National Institute of Virology in Kolkata and Mumbai, reported The Hindu.
“We are still examining the issue,” Sangma told reporters in Meghalaya’s capital Shillong. “It is a very serious situation that will be reviewed soon.”
The oral polio vaccine contains an attenuated form of the virus, which stimulates an immune response in the body.
During this process, the vaccine-virus is excreted. In rare cases, if a population is significantly under-immunized, the excreted virus can circulate for an extended period.
As it persists, it undergoes genetic changes. In very rare instances, these changes can lead to the vaccine-virus evolving into a form that can cause paralysis, known as a circulating vaccine-derived poliovirus, according to the World Health Organisation.
Over 10 billion doses of oral polio vaccine have been administered to nearly three billion children worldwide since 2000. In this period, a total of 24 outbreaks of circulating vaccine-derived poliovirus have occurred in 21 countries, leading to fewer than 760 cases of vaccine-derived poliovirus.
“Circulating VDPVs [vaccine-derived poliovirus] in the past have been rapidly stopped with two to three rounds of high-quality immunization campaigns,” says the World Health Organisation. 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.”
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