Abuja, Aug 15 (IANS): A case of the Circulating Vaccine-Derived Poliovirus (VDPV) type 2 was detected in Nigeria's northern state of Adamawa, marking the re-emergence of the disease, local authorities said.

The new case was detected a year after the World Health Organization (WHO) declared Nigeria a polio-free nation, reports Xinhua news agency.

Abdullahi Isa, health and human services commissioner in Adamawa, who confirmed the new case during the flag-off of a first-round outbreak response immunisation against polio in the state, did not say when exactly the case was detected.

Isa described the VDPV as "a strain of the weakened poliovirus that was initially included in Oral Polio Vaccine (OPV) that has changed over time and behaves more like the wild or naturally occurring virus".

The new case, which has resurfaced, makes the outbreak of the transmitted virus possible, he said.

"The resurface of the poliovirus type 2 necessitated the immediate flag-off of the first round outbreak response for the OPV," Isa said.

About 800 health personnel have been trained as vaccinators in the ongoing immunisation campaign against poliovirus in Adamawa, with support from WHO and the Unicef, among others.

Around 1 million children below five years old are targeted in the outbreak response vaccination campaign across the state.

"WHO is working hand in hand with the state government to ensure total eradication of the virus and to ensure every eligible child is vaccinated against polio," said Iyobosa Igbinovia, the WHO coordinator in Adamawa.