Toddler's rare bird flu worries experts
The results of further viral tests on a two-year-old boy who was infected by avian flu in Guangdong have health experts worried as there is no vaccination so far to stop the particular strain from circulating among poultry.
The boy, who came to Hong Kong from Guangdong, was confirmed to have caught bird flu last week. He remains in serious condition in the paediatric intensive care unit at Princess Margaret Hospital.
Further viral tests yesterday confirmed that the H5 gene of the virus sample taken from the boy belonged to the 22.214.171.124 clade, the Centre for Health Protection (CHP) said.
Dr Lo Wing-lok, a microbiologist, said this was a relatively new strain discovered on the mainland two years ago.
'The mainland is very worried about 126.96.36.199 ... The vaccination now used on poultry is not wholly effective against this type,' he said.
Lo said the current vaccine could suppress flu symptoms on birds so that even infected birds appeared healthy. 'But the virus is still circulating among the 'healthy' poultry,' he said.
But based on his past experience, he said it would be difficult for the strain to mutate and spread widely among humans.
'It would need to mutate many times to be able to circulate among humans. But it is widely circulating among chickens. So the chance for human infection [from birds] will be higher,' he said.
Lo said researchers in the mainland and Hong Kong were developing and testing new vaccines but the process would take time. He estimated that the virus would continue to spread among poultry and that the situation could deteriorate before a new vaccine was available.
The CHP said the 188.8.131.52 clade was the same as samples from wild birds detected last year and this year, and the imported human infection case in late 2010.