A Pakistani health official says a special five-day anti-polio drive is being launched in the capital of southwestern Baluchistan province after traces of polio virus were found in the sewer system.

Syed Faisal Ahmed, the coordinator for Emergency Operation Centre in Quetta, said Monday that some 400,000 children under age five will be immunized against the .

He said decision to launch the special drive was made after environmental samples in Quetta confirmed the presence of the virus. Ahmed said 1,345 teams will cover 39 local councils of the city amid tight security.

Multiple anti-polio drives enabled Pakistan to announce last year that the virus had largely eliminated.

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