Controller of the Centre for Health Protection Thomas Tsang (left) and Tse Hung-hing, a representative of the Hong Kong Medical Association, show media an illustration of strawberry tongue, a symptom of scarlet fever, on Monday. Edmond Tang / China Daily

University scientists discover mutation of potentially deadly virus fuels record outbreak

Scientists at the University of Hong Kong have warned that the strain of scarlet fever that has already killed two children and infected dozens of others has mutated and become more contagious.

"This (mutation) may nicely explain the 'unusual' large outbreak of the scarlet fever in Hong Kong recently," Thomas Tsang, director of the Centre for Health Protection (CHP) said on Monday.

He added that the Chinese mainland and Macao also face widespread outbreaks of the disease.

The strain has already shown resistant to several antibiotics normally used to treat the disease.

The scientists, confronted with a record 419 cases so far this year and the newly developed resistance to antibiotics, began to suspect that genetic mutation may be responsible.

The research led them to a unique genome fragment reflecting a genetic recombination of Group A Streptococcus pyogenes, the virus which causes scarlet fever.

The scientists believe this mutation may have contributed to the increase in transmissibility of the strain, and may account for the fact that the number of cases of scarlet fever is multiply higher than the number recorded last year.

The researchers added the findings provide important genetic information for tracking the spread of the new strain.

"With 100 cases in May and 142 cases in June, we believe the high incidence of the disease will continue for months in this summer," noted Tsang.

The current outbreak has already claimed the lives of a 15-year-old boy and a 7-year-old girl.

They are the first recorded deaths from the disease in Hong Kong over the past decade.

Dr Tse Hung-hing from Hong Kong Medical Association suggested the doctors use penicillin group of antibiotics instead of erythromycin for treatment.

He also advised parents to take children to the hospital as early as possible when the patients present the clinical symptoms of scarlet fever, including fever, sandpaper rash, sore throat and strawberry tongue.

However, he also pointed out there's no need for panic.

Usually the fever can be controlled within 48 hours with antibiotics if the patient gets the proper treatment in the early phase.

In total 90 percent of the cases reported have occurred outside schools and kindergartens, and no consideration has been given to starting the summer holidays ahead of schedule, said Tse.

The CHP said it will enhance cooperation with the schools and kindergartens to avoid a larger-scale outbreak, and work closely with the related departments on the mainland and Macao to tackle the problem.

Scarlet fever bacteria are transmitted through either the respiratory tract or through direct contact with infected respiratory secretions. Usually children aged 2-10 are most susceptible.

China Daily

(HK Edition 06/21/2011 page1)