Director of Health Dr Ronald Lam highlights notably shorter incubation period in mosquitoes, allowing virus to replicate quickly.

Case involves woman, 66, just returned from Guangdong province, while another probable patient under observation after three-country trip.

City’s five cases recorded in a week are ‘from the mainland or imported from overseas’, Eric Chan says.

Director of Health Dr Ronald Lam highlights notably shorter incubation period in mosquitoes, allowing virus to replicate quickly.

Hong Kong has recorded six imported cases since August 2, with a 31-year-old man who returned from Foshan the latest patient.