The authorities have launched an anti-mosquito operation on Cheung Chau after a second dengue fever case was confirmed on the outlying island.

It is the 16th reported local case this year – all of which have emerged over the past week.

The latest patient, a 52-year-old male with an underlying illness, lives on Tsan Tuen Road and works in Lai Chi Kok. He recalled receiving a mosquito bite on Fa Peng Road on Cheung Chau.

mosquitos Cheung Chau

During the incubation period, the patient travelled to Dongguan in Guangdong for a day trip. He was hospitalised on Saturday and his condition remains stable.

The patient’s blood sample tested positive for dengue virus serotype 3, which was different from the other 15 patients who tested positive for dengue virus serotype 1.

“We are not 100 per cent sure if the source of infection was Cheung Chau,” said Dr Wong Ka-hing, controller of the Centre for Health Protection. “If the source of infection for the latest patient was also Cheung Chau – which is quite likely – it means that there may be more than one source of infection on Cheung Chau.”

Second case

It is the second case detected on Cheung Chau after another was reported last Tuesday. The first case, an 84-year-old female patient also with underlying illnesses, lives on Hill Side Road on Cheung Chau.

However, she had no travel history during the incubation period. She mainly stayed at home and did not recall attracting any mosquito bites.

Investigations showed that the genetic sequences of the virus in the first Cheung Chau case differed from the others. It means that there could be three different sources of infection, two of which could be in Cheung Chau.

mosquitos Cheung Chau

Wong said that symptoms were usually mild for people who were infected with dengue fever for the first time, but it could turn much more serious for second infections, where haemorrhaging can occur.

Last Friday, the authorities decided to close Lion Rock Park in Wong Tai Sin for a month after several people who worked at – or visited – the park were infected with dengue.

There was only one local case of the disease last year. There were four in 2016 and two in 2015.

Secretary for Food and Health Sophia Chan shortened her holiday to handle the situation.

Chan has notified the chief secretary that she will now return on August 29 after a work trip to Conghua, Guangdong between August 27 and 28. She was originally due to return on September 5.

Kris Cheng is a Hong Kong journalist with an interest in local politics. His work has been featured in Washington Post, Public Radio International, Hong Kong Economic Times and others. He has a BSSc in Sociology from the Chinese University of Hong Kong. Kris is HKFP's Editorial Director.