The Centre for Health Protection on Monday said that Wong Tai Sin District doesn't have a high rate of mosquito activity, but officials would step up control efforts there after the discovery of the first locally-infected chikungunya fever case.

It announced on Sunday that an elderly woman living in Fung Tak Estate in Diamond Hill was infected, and was said to be in stable condition.

The centre's controller, Edwin Tsui, said despite the relatively lower activity rate, small amounts of mosquitoes could still transmit the disease, and officials would monitor the situation for around two weeks.

"It depends on how fast we could minimise the mosquito population [in Wong Tai Sin] this week, then the risk of infection would naturally reduce," he said on an RTHK programme.

"While we have discovered the first case, it's also possible that some hidden cases exist, but the patients do not have symptoms... or cases where individuals already have symptoms but haven't seen a doctor because they don't suspect it's chikungunya fever."

Tsui said it's possible that more cases would be discovered in the area through the authorities' active case tracing.

He noted that while Wong Tai Sin could be of higher risk, it doesn't mean that other districts are risk-free, and therefore government officials would hold a cross-departmental meeting on Monday to discuss large-scale anti-mosquito work in other districts.

Tsui called on the public to contact the centre if they suspect they have been infected, adding that an education seminar on the disease would be held at Fung Tak Estate on Monday night.

He went on to stress that serious complications and mortality rates borne out of chikungunya fever infection are relatively low, at less than one per 1,000 patients.