The Department of Health warns that Dengue fever may pose a threat this summer, with 23 imported cases reported this year, a threefold increase over the six reported in the same period last year.

The department's Disease Prevention & Control Division consultant Dr Thomas Tsang said today the number of Dengue fever cases remains high in Southeast Asia, where most imported cases are sourced.

He warned that Hong Kong may see a return of local cases, following 20 such cases last year. The best prevention is to eliminate stagnant water where mosquitoes can breed.

To help in the early detection of infectious diseases, the department has been monitoring the local incidence of communicable diseases through numerous surveillance systems.

The consultation rates for influenza-like illnesses have increased since June, marking the arrival of the second high season for flu this year. The first high season was January to March.

Of the viruses isolated from patients' samples from January to May, 66.1% were found to be Type A H3N2 virus, the common strain found in Hong Kong.

In view of several institutional outbreaks in July, department staff have visited all 750 elderly homes in Hong Kong to provide infection control guidelines and promote hygiene awareness.

Food poisoning figure down 36%

Summer is also the high season for food-borne diseases, Dr Tsang said. In June and July, three local cases of cholera were reported. All patients had a history of eating raw or inadequately cooked seafood. 

Although the half yearly figure for food poisoning showed a 36% decrease from the same period last year, the public should exercise extra caution during summer.

Meanwhile, Dr Tsang said the incidence of acute conjunctivitis was low in the first half of this year. However, the department would continue to monitor the situation as there was an upsurge in August and September last year following a similar period of low incidence.

The incidence of hand, foot and mouth disease remained low this year, in contrast to the upsurge last summer.

For more details on the trends for various infectious diseases and health advice on their prevention,  visit the department's website and the Central Health Educational Unit's website.