The monthly average ovitrap index fell to 7.4% in November, down from 13.7% in October, the Food & Environmental Hygiene Department says.

Ovitrap indices reflect the prevalence of Aedes albopictus, a mosquito vector for Dengue fever transmission.

Of the 38 areas surveyed, 37 recorded positive indices, ranging from 1.9% to 19.3%. But none entered the alert zone of 20% to 40%.

The three areas with the highest indices were Cheung Sha Wan (19.3%), Diamond Hill (16.4%) and Chai Wan West (15.1%).

The index for port areas fell to 0.5% from 0.8%.