Hong Kong authorities confirmed four local cases of dengue fever on Tuesday and said there was a risk of a major outbreak.
The Department of Health’s Centre for Health Protection (CHP) urged the public to maintain strict environmental hygiene, mosquito control and personal protective measures both locally and during travel.
CHP Controller Wong Ka-hing said on Tuesday that it was “unusual and unprecedented” for four local cases to be confirmed in a single day.
“The most important thing is we have to be cautious about an outbreak,” Wong said. “In neighbouring places, there had been major outbreaks of locally transmitted dengue fever, which could happen [here].”
The patients include a 17-year-old male, a 78-year-old male, an 84-year-old female and a 76-year-old female. They developed symptoms of the mosquito-borne disease on August 7 and 8 and sought medical help afterwards.
Three of them had not travelled abroad during the incubation period of the disease. One patient displayed symptoms while she was in Japan, but her case was determined to be a local one. They also live in different neighbourhoods and had no activity in common, the CHP said.
One of the patients recalled playing baseball frequently at Sai Tso Wan Recreation Ground in Lam Tin, where there were a lot of mosquitos, he said. Another patient recalled being bitten by mosquitos after swimming at Clear Water Bay Second Beach.
The CHP urged anyone with dengue fever symptoms to call their hotline on 2125 1122 if they had been in the vicinity of Sai Tso Wan Recreation Ground, Highland Park, Kwai Shing West Estate, Clear Water Bay Second Beach, Hill Side Road, Tsui Chuk Garden, Fung Wong San Tsuen or Lion Rock Park.
Wong said that locally contracted cases of dengue fever are uncommon in Hong Kong, with zero to four cases recorded per year over the past few years.
As for imported cases, 55 cases had been recorded in 2018, including 25 from Thailand, 10 from the Philippines and seven from Cambodia.
According to the World Health Organization, dengue fever is a severe, flu-like illness that affects infants, young children and adults, but seldom causes death.
Dengue may involve a high fever accompanied by two of the following symptoms: severe headache, pain behind the eyes, muscle and joint pains, nausea, vomiting, swollen glands or rash, the WHO said.
“We are working closely with the Food and Environmental Hygiene Department to assess and prevent any possible spread of infection. The FEHD’s vector investigations, surveillance and control will follow,” a CHP spokesperson said.
“The Leisure and Cultural Services Department, Home Affairs Department and Hong Kong Baseball Association have also been informed for follow-up. Epidemiological investigations are ongoing,” the spokesperson added.