Scarlet fever is characterized by a sore throat, fever, and strawberry-red tongue. (Kronawitter/Wikipedia commons)

With more than 400 cases of the disease this year, including the death of a six-year-old last month, officials are warning of an outbreak of scarlet fever in the special administrative region. A five-year-old boy may also have died from the infection, which is spread by coughing and sneezing.

Scarily, scientists in Hong Kong say the bacteria may be spreading more quickly than normal due to a genetic mutation, BBC reports.

Once a major cause of death, scarlet fever can now be effectively treated with antibiotics. But this new strain of scarlet fever appears to be resistant to those antibiotics, according to Channel News Asia.

Scarlet fever happens every year in the region. This year infections have also gone up by nearly five times in China, and three times in Macau, with nearly all infections affecting children under 10.

Hong Kong has been particularly nervous about infectious diseases since the 2003 SARS outbreak, which killed 300 people in the city and a 500 more around the world.