Anew strain of bird flu has surfaced in China and it has health officials alarmed. While the death toll has reached double digits, the real cause of concern is the fact that it was previously not known to affect humans. Health officials in China and elsewhere are closely monitoring hospitals and clinics, as well as the close contacts of confirmed cases.

Surveillance is critical, not only of people, but also of poultry to trace the source of the outbreak and identify its vectors, as well as isolate the strain and prepare a vaccine.

The new flu comes from the H7N9 virus, a variant that has long been in pigeons but has never been found in humans. Apparently, the virus has mutated and now affects mammals. Thus far, Chinese health authorities report it has infected at least 84 people in the cities of Shanghai and Beijing plus four Chinese provinces, killing 17 people over the last two months, all in eastern China.