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Friday, August 12, 2016, 01:02

Health Dept warns of increase threat of mosquito-borne diseases

By Sylvia Chang

HONG KONG - In the next two months Hong Kong will be under greater threat of outbreaks of mosquito-borne diseases, including dengue fever, Japanese encephalitis and Zika virus infection, the Health Department warned on Thursday.

More people are coming to visit Hong Kong during the summer vacation and residents will return from the Olympics in Brazil where Zika and dengue fever are prevalent.

Because of this the city risks importing mosquito-borne diseases, said Leung Ting-hung, chairman of the Interdepartmental Coordinating Committee on Mosquito-borne Diseases.

Leung, who is also controller of the Centre for Health Protection (CHP), urged the public to take more measures to prevent infections.

Since mid-July Hong Kong has recorded this year’s first cases of dengue fever and Japanese encephalitis, both of which are suspected to be locally acquired, he said.

Four imported cases were confirmed during the past week. The patients had traveled to the Philippines, Bangladesh and Indonesia during the incubation period. So far the city has recorded 72 imported dengue fever cases this year.

Meanwhile, the city’s detective system, Oviposition Trap (Ovitrap), has identified the first Japanese encephalitis positive sample of local Culex quinquefasciatus, a Japanese encephalitis vector mosquito. The system also has confirmed the rising number of Aedes albopictus, a mosquito transmitting dengue fever virus.

The latest index of Ovitrap shows that seven areas in the city have reached the alert level. This indicates that infestation of Aedes albopictus has exceeded one fifth of the area surveyed.

These areas include Tuen Mun North, Tin Hau, Yuen Chau Kok, Kai Tak North, Deep Water Bay and Repulse Bay, Tsim Sha Tsui East and Ngau Chi Wan.

The usual annual anti-mosquito campaign will focus on education and training. Hong Kong will also conduct an “intensive mosquito prevention and control exercise” from August to October, said Lee Ming-wai, the pest control officer in-charge from the Food and Environmental Hygiene Department.

Heavy rainfall and abnormally hot weather will hit the city in the coming weeks. This will create more ditches favorable for mosquitoes to breed. Such places exist in cans, discarded tires, tree holes, rock pools and bamboo ends.

Local experience shows that dengue fever and Japanese encephalitis patients had visited parks, work sites, housing estates, villages and rural areas. The government suggested the public avoid frequent visits to these places.

The mosquito is one of the deadliest creatures in the world. Every year, millions of deaths are caused by the spread of mosquito-borne diseases. Dengue fever, Japanese encephalitis and Zika are only three of these diseases.

A patient infected by dengue fever or Japanese encephalitis will suffer fever, headaches, pains in the muscles and joints, a loss of appetite, and in severe cases circulatory failure, shock and even death. Symptoms usually start three to 14 days after being infected.

However, a Zika-infected patient may not have apparent symptoms. Sixty percent of patients do not have fever. The incubation period can last 19 days.

The CHP’s Leung said 10 clinics of the Hospital Authority have been reserved for residents who will return from trips to Brazil. He urged them to find out if infectious diseases were suspected.

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