Chandigarh, Sep 6 - Doctors and para-medical staff in Chandigarh have been asked to take extra precautions against swine flu after the influenza A (H1N1) virus affected some of them in government hospitals here, an official said Sunday.

Four doctors and two other staffers of the administrative department of the Postgraduate Institute of Medical Education and Research (PGIMER) and Government Hospital here in Sector 32 have tested positive in the past. Besides, the daughter of a senior doctor also got infected with H1N1.

Now new samples have been sent for testing.

'We had collected samples of throat and nasal swabs of four patients on Saturday that included three doctors (two from PGIMER and one from Sector 32 hospital).