The Telangana government on Tuesday declared a “global emergency” after an active strain of wild polio virus (P2 strain) was detected in samples of sewage water in the state capital Hyderabad.

Over two lakh vaccines have been air-lifted from Geneva, Switzerland after the virus was detected. More than three lakh children in the city and Ranga Reddy district will be vaccinated as a “preventive measure” from Wednesday onwards.

The virus (vaccine derived polio virus type-II) was found in the lab tests conducted on samples of water collected from Amberpet sewage treatment plant on May 17, during a routine surveillance of 30 samples collected from various parts of Hyderabad.

About 3,50,000 children, aged six weeks to three years, will be vaccinated in the weeklong campaign, which will start on Monday, said Rajeshwar Tiwari, Principal Secretary (Health) of the state government. “The government decided to conduct a special campaign against polio here and in parts of Ranga Reddy district from June 20 to June 26,” Mr. Tiwari added.

In 2014, India was declared polio-free by the World Health Organisation (WHO). Since January 2014, India has reported at least four occurrences of vaccine-derived polio but here have been no cases of infection from the wild polio virus since January 2012. However, the Vaccine Derived Polio Virus (VDPV) strain must be contained because neighboring and West Asian countries, which are well connected with Hyderabad, continue to see new cases.