All the four members also tested positive for the Swine Flu virus, Yadav said.
"Bilal might have contracted the infection from the PGI campus and passed it on to his family members. The director of PGI has been asked to look at the probable causes of the spread of the virus," he said.
According to him, as a precautionary measure, Bilal's neighbours were also tested but all of them were found to be safe.
However, they have been asked to remain alert and inform medical authorities in case if they had any problem, he said.
A retired Lance Naik died of H1N1 virus on January 9, while wife of a retired jawan died due to Swine Flu on January 13 in Lucknow.