Chinese health officials reported Tuesday that there are four new cases of bird flu. In a notice on its website, the health bureau of eastern Jiangsu reports that three women and one man are critically ill with the H7N9 virus.  The World Health Organization says this new strain of bird flu is not transmitted between humans.

The new form of bird flu, H7N9, killed two residents in Shanghai, according to reports from China's official news agency Sunday. The two male victims both contracted the H7N9 bird flu strain in February and died in March after becoming critically ill.

About the new illnesses, WHO representative in China Dr. Michael O'Leary said Monday, "At this point, these three are isolated cases with no evidence of human-to-human transmission."

Chinese officials are warning people about the deadly bird flu outbreak with advice published in the Oriental Morning Post that says, "Wash your hands, and cover your nose and mouth when coughing or sneezing. And avoid eating or contact with dead and diseased livestock."

Dead, diseased pig carcasses were floating in Shanghai's Huangpu River since early March and concern about the safety of the water was a concern for locals. Many Chinese microblogs known as "weibos" suspect that the dead pigs are the cause of the bird flu outbreak.

Nothing was officially confirmed, but over 11,000 pigs were recently removed from the river, which is the source of the city's water supply. Other reports are that the number was high as 16,000 pig carcasses. Officials never said exactly what it was that infected the pigs that were then cast into the river by local farmers. O'Leary from the WHO said that the origin of bird flu outbreak is currently being probed by the WHO, and the dead pig carcasses are part of the overall investigation.