Hong Kong’s Aedes albopictus mosquito index falls further in October
Hong Kong’s monthly Aedes albopictus mosquito index dropped to 2.9 per cent in October, with all 62 monitored areas below the 20 per cent alert level. The Food and Environmental Hygiene Department attributed the decline to intensified control measures and weather, and will maintain enhanced operatio
The Food and Environmental Hygiene Department announced on 12 November 2026 that the territory-wide monthly Gravid Trap Index for Aedes albopictus – the mosquito species that transmits dengue and chikungunya – fell to 2.9 per cent in October, a Grade 1 level indicating low mosquito distribution. All 62 surveillance areas recorded district indices below the 20 per cent alert level. The department said the drop resulted from sustained anti-mosquito efforts by government departments and stakeholders, and possibly from weather factors.
The monthly Density Index for Aedes albopictus stood at 1.1 in October, meaning traps that caught mosquitoes contained an average of 1.1 adult mosquitoes, indicating low adult mosquito numbers overall.
A department spokesman said that since August 2025, enhanced mosquito control work – previously triggered only when a district index reached 20 per cent (Grade 3) – has been expanded to when the index reaches between 10 and 20 per cent (Grade 2). With indices continuing to fall, the department will maintain this arrangement until further notice. The spokesman noted that imported mosquito-borne diseases and secondary transmission risks remain, as neighbouring areas continue to report dengue and chikungunya cases.
Starting November 2026, the department will revert to releasing the monthly index, density data and prevention information through a single monthly press release and social media, rather than issuing separate announcements for each district. The department will continue to post updated district indices on its website.
Although autumn has arrived, the spokesman warned that warm weather and intermittent rain still favour mosquito breeding. The department continues to carry out control measures across districts, including removing breeding sites, applying larvicide, fogging to kill adult mosquitoes, and setting traps. It also conducts site inspections, provides technical support, and runs public education campaigns.
The department’s third territory-wide anti-mosquito campaign ended on 23 October 2026, covering residential areas, schools, construction sites, public housing estates, hospitals, illegal farmland, waterfront cargo areas, border checkpoints, typhoon shelters and ferry piers. The first and second phases of a citywide campaign began on 25 March and 30 April 2026, with work continuing. The department urged private property managers to join the citywide effort.
Residents are advised to eliminate standing water weekly, change vase water and scrub flower-pot bases, properly dispose of containers, keep drains clear, and fill depressions to prevent water pooling. Those travelling to Southeast Asian countries should be aware of local disease risks and seek medical advice if feeling unwell upon return.
