Health authorities voiced concern after four cases of dengue fever were reported in the city in just one day.
At 5 p.m. on Tuesday, the Department of Health’s Centre for Health Protection (CHP) confirmed the first local case of dengue fever this year, involving a 17-year-old boy living in Highland Park in Kwai Chung.
This was followed by three other cases involving patients in their 70s and 80s, which the CHP confirmed at 9:30 p.m.
CHP controller Dr. Wong Ka-hing said the center is highly concerned about the unprecedented and unusual situation in which so many dengue fever cases emerged in such a short period of time, i.e., between Aug. 2 and 8, the Hong Kong Economic Journal reports.
Wong said it is not known if the four cases shared the same source, but the patients live in different places and had not been to a common area shortly before they were infected.
He said it would take two to four weeks to determine if there is an outbreak.
In the first case, the boy started to developed fever, sore throat and muscle and joint pains on Aug. 7 before he was admitted to Hong Kong Baptist Hospital on Aug. 12. He skin rashes on his left lower limb after admission.
Investigation revealed the boy, who is now in stable condition, had no travel history during the incubation period but frequently went to Sai Tso Wan Recreation Ground in Lam Tin to play baseball.
He said there were a lot of mosquitoes at the site, although he could not recall having had any mosquito bites.
Lee Ming-wai, pest control officer-in-charge at the Food and Environmental Hygiene Department (FEHD), said an ovitrap index showed signs of Aedes albopictus, the mosquito that carries the dengue fever virus, in the vicinity of the Highland Park as well as in Sai Tso Wan.
Lee urged the public to take steps to clear any water accumulation near their homes where mosquitoes could breed.
Those who contracted dengue fever on the same day included a 78-year-old man living in Kwai Shing West Estate in Kwai Tsing District, an 84-year-old woman living on Hill Side Road in Cheung Chau and a 76-year-old woman living in Tsui Chuk Garden in Wong Tai Sin, the CHP said.
The four patients’ companions at home were also put under medical surveillance, although they have remained asymptomatic.
A CHP spokesman said it is working closely with the FEHD to assess the situation and prevent any possible spread of the disease. The Leisure and Cultural Services Department, the Home Affairs Department and Hong Kong Baseball Association have also been informed of the cases.
The FEHD is devoting two months to strengthening mosquito preventive and control work in areas within 500 meters from the residences of the patients and the places they visited during the incubation period.
Dengue fever is an acute mosquito-borne infection caused by the dengue virus. It is clinically characterized by high fever, severe headache, pain behind the eyes, muscle and joint pain, nausea, vomiting, swollen lymph nodes and rashes.
Those infected may or may not manifest symptoms, while some may only have mild symptoms such as fever.
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