Hong Kong stands a 'very high' chance of seeing an outbreak of dengue fever unless it puts effective disease-control measures in place, an expert from the World Health Organisation warned yesterday. The warning follows the confirmation of 14 dengue fever cases and 19 suspected cases in Macau on Wednesday. Extermination of mosquitoes began in the enclave yesterday. The caution also came as health authorities disclosed that an eighth SAR person this year had come down with the fever. The 47-year-old woman, who fell ill in the middle of the month, had travelled to a Southeast Asian country, a spokeswoman for the Health Department said. All eight cases have been classified as imported, with patients mostly travelling to Southeast Asia during the incubation period. All have recovered. SAR authorities also announced an expanded mosquito-extermination programme to begin today and last until November 3. Disease surveillance and public education, particularly at ferry terminals and border-control points, will be enhanced. 'Chances are very high [of a local spread],' said Dr Kevin Palmer, the World Health Organisation's authority on dengue fever for the Western Pacific region, which includes the mainland. 'You are in the middle of an area of dengue-fever epidemics. It is a big city, with people coming in and out and a potential for breeding areas for mosquitoes . . . I'd put Hong Kong in a high category of risk for dengue,' Dr Palmer said, adding the Government had to carry out mosquito control. Dr Tse Lai-yin, chairwoman of the Hong Kong Government's Inter-departmental Co-ordinating Committee on Dengue Fever, said yesterday she would not rule out the possibility of the fever spreading locally, although she said the SAR had been lucky so far in keeping it out. Dengue fever produces pain in the limbs and back in its early stages and sometimes fatal internal and external bleeding in more serious cases. Since 1994, three to 15 cases have been reported in Hong Kong each year - all imported, Dr Tse said. Dr Ho Yuk-yin, of the Food and Environmental Hygiene Department, said dengue-carrying mosquitoes were abundant in the territory. 'So far, we have been successful [in controlling local transmission] and there are no local cases,' Dr Ho said.