HONG KONG - Hong Kong's health authority said Tuesday that the 2-year-old boy confirmed with Influenza A (H5N1) infection on Saturday is currently receiving intensive care at Princess Margaret Hospital and his condition remained serious.

According to the health department's investigation, the H5 gene of the isolate belonged to clade 2.3.2.1, which is the same clade as the isolates from wild birds detected in 2011 and 2012 and in the imported human infection case in late 2010.

So far, all the genes characterized belong to avian origin and there is no evidence of resistance to the antiviral agent oseltamivir (Tamiflu).

The department has kept some 80 contacts under medical surveillance. Nasopharyngeal aspirates taken from the parents and the five contacts who have reported respiratory symptoms tested negative for Influenza A (H5N1).

The boy developed fever and runny nose on May 23 in Guangdong. He came to Hong Kong on May 26 and sought medical attention from a private medical clinic in Mong Kok. He developed febrile convulsion and was taken to the Accident and Emergency Department of Caritas Medical Center on May 28.