New Delhi, Aug 9 - Health Minister Ghulam Nabi Azad Sunday said swine flu was very contagious and those who have fallen victim to it could have passed on the virus to many others.

He told reporters that school girl Reeda Shaikh, who died Aug 3 in a Pune hospital, had visited more than one hospital for treatment and thus could have spread the virus to about 80 others.

'One small girl went from one hospital to another, then a third hospital to get treatment and then a fourth, without awareness. In the process some 80 people were infected. This girl ... transmitted the virus in the course of seeking treatment,' he said.

The 14-year-old student was India's first swine flu victim. She died Aug 3.

Azad added: 'When it comes to passengers from London or the US, they are educated and have a wide social network -- it (virus) spreads fast. One person can transmit it to 100 more, they to 1,000 people, and then 10,000 to a lakh (100,000) and then to a crore (10 billion),' Azad said.