Shanghai, Apr 6 (IANS/EFE): The toll from an outbreak of a new strain of bird flu in eastern China rose to six Friday with the deaths of a farmer in Zhejiang province and two other people in this metropolis.

Doctors have confirmed 13 other cases of infection with a variant of the H7N9 virus.

All 13 patients are being treated under quarantine at hospitals in Shanghai and neighbouring regions.

Only one person who was in contact with the infected people has shown any symptoms.

Authorities in Shanghai ordered the slaughter of 20,536 birds at the city's live-bird market after H7N9 was detected in a dove there.

As more cases are confirmed, experts are collecting more information and material that can provide clues about the nature of the new strain and how it is spread, Shanghai chief epidemiologist Wu Fan said in statements published by the Shanghai Daily.

The World Health Organization said a pandemic is unlikely, given that there is no evidence of person-to-person transmission of the virus.

The source of contagion could be contact with birds or mere proximity to them, WHO spokesman Gregory Hartl said in Geneva.