The recent death of 11 months old Indian baby, in Maharashtra state, afflicted from vaccine-derived polio led to speculations of another round of polio outbreak in the country.
India completed two years without any case of polio on January 13, 2013—marking an unprecedented progress for a developing country that accounted for almost half the world’s polio cases in 2009. The disease usually affects children under five.
The Indian Health Ministry, clearing away the doubts of any such outbreak, said in a press statement that the main cause of the boy’s death was brain infection, who was admitted at a government hospital on May 7, after a month-long illness. The boy succumbed on June 22.
Vaccine-derived polio virus (VDPV) is extremely rare, and detected in children with immunodeficiency or in populations with low levels of immunization.
“The most important strategy for prevention of emergence of VDPVs is achieving and maintaining high routine immunization coverage with OPV [Oral Polio Vaccine] doses among infants,” said Secretary Keshav Desiraju from the Indian Department of Health and Family Welfare, in the official statement.
The OPV contains a live, weakened vaccine-virus. After vaccination, the weakened vaccine-virus replicates in the intestine and enters into the bloodstream, triggering a protective immune response in the child. The virus is excreted for a certain time, eventually providing immunity to the nearby population; but some of the vaccine-virus may undergo genetic alterations, eventually becoming even more fatal.
VDPVs are different from wild polioviruses and India has not reported any case of polio due to a wild poliovirus since January 2011.
The health ministry said that the detection of VDPVs will not impact the polio eradication certification process. The pre-requisites for polio free certification of a region includes absence of wild poliovirus in all countries of the region for three consecutive years, presence of certification standard surveillance, and the completion of laboratory containment activities.
“Though India has not reported any case of polio for over two years, an importation of wild polio virus remains the larger threat to the children in India, especially in view of close proximity to polio endemic Pakistan and Afghanistan,” said Dr. Nata Menabde, World Health Organization representative, in the press release.