The Department of Health has launched an investigation after the death of a 14-year-old girl from scarlet fever yesterday. This follows a 10-fold increase last year in the number of children struck down by the potentially fatal bacteria.
Another victim - an 11-year-old boy who attends St Joseph's Primary School in Wan Chai - was in stable condition in the intensive care unit at Pamela Youde Nethersole Eastern Hospital in Chai Wan. He was transferred two days after being admitted to a private hospital on January 15.
St Joseph's school has closed for the Lunar New Year holiday, while St Paul's Secondary School in Happy Valley, which the girl attended, will close today - one day earlier than usual - to prevent an outbreak.
The schools would be thoroughly disinfected, health officials said.
A microbiologist believes a mutation that might make the bacteria more infectious may be the reason for the unusual outbreak in recent months.
'It is rare to find scarlet fever attacking children above the age of 10,' said Dr Thomas Tsang Ho-fai, the controller of the Centre for Health Protection, who announced the investigation yesterday.
He said more than 90 per cent of cases occurred in children below the age of 10.
'We will also look into the DNA composition of the bacteria to see whether there has been a mutation to make it more drug resistant or fatal,' Tsang said.
The girl who died developed flu symptoms including a fever and a runny nose on January 6. She had gone to three private doctors but her condition deteriorated and she was sent to Eastern Hospital.
Tsang said the department would also look into whether a delay in treatment contributed to her death.
The girl's mother and younger brother also developed slight flu symptoms, Tsang said.
The number of scarlet fever cases had seen an almost 10-fold surge, jumping from 128 cases in 2010 to 1,534 last year. Of those, 14 cases required intensive care and two subsequently died of the bacteria, while no deaths were recorded in the previous two years.
The number of infections peaked last summer, with 407 infected in June and 297 infected in July. After the summer the number of cases fell below 100 each month, Tsang said. But in December and January, cases rose again, with 150 and 83 being confirmed so far - a level above normal.
'Winter is another normal peak season for the bacteria, but we are worried that the total number of cases this year may also hit a high, with two serious cases already,' Tsang said.
He reminded parents to stay alert to any symptoms emerging in their child, which include developing a distinctive strawberry-like tongue with a red and bumpy appearance, as well as normal flu symptoms such as fever and a sore throat.
Another microbiologist, Dr Lo Wing-lok, said: 'The death rate for scarlet fever is around 1 to 2 per cent, and it has not been a very fatal rate. But with the large number of infections, the risk of serious cases occurring also increases.'