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Dengue Fever Ovitrap Index Update

Starting from October 2015, there are a total of 52 locations selected for the vector surveillance.  Two different indices, namely Area Ovitrap Index for Aedes albopictus (AOI), and Monthly Ovitrap Index for Aedes albopictus (MOI), would be enumerated.  AOI indicates the extensiveness of the distribution of Aedine mosquitoes in that particular area surveyed while the MOI is the average of all AOIs within the same month, which reflects the territory-wide situation of Aedes albopictus.

Survey of Aedes albopictus has been carrying out in Hong Kong International Airport since 1998. Starting from 2004, dengue vector surveillance work would be extended to other port areas. Two different indices, namely Port Ovitrap Index for Aedes albopictus (POI), and Port Monthly Ovitrap Index for Aedes albopictus (PMOI), would be enumerated. POI indicates the extensiveness of the distribution of Aedine mosquitoes in particular group of surveyed port areas while the PMOI is the average of all POIs within the same month, which reflects the overall situation of Aedes albopictus in port areas.

The Ovitrap Index for Aedes albopictus can be classified into 4 levels. Specific preventive and control measures will be initiated accordingly. Management of housing estates, hospitals, schools, construction sites and other venues or properties are also advised to take specific measures to contain mosquito problems in their own properties. The 4 levels of Ovitrap Index for Aedes albopictus and actions to be taken by the management are listed in the following table.

Classification Ovitrap Index for Aedes albopictus Action to be taken
Level 1 O.I. < 5%

- Closely monitor the hygienic condition to prevent breeding of mosquitoes;

- Conduct weekly inspection to identify breeding / potential breeding places and eliminate such places as far as possible.

- Public are advised to check and eliminate any possible breeding places within their premises at a frequency not less than once a week (Please go to Advice to Public for details)

Level 2 5% O.I. < 20%
Level 3 20% O.I. < 40%

- To conduct special operations in addition to the regular weekly program to eliminate all breeding / potential breeding places;

- Private pest control contractor might be employed to control the mosquito problem.  Other control measures by using larvicides or adulticides might be feasible.

Level 4 O.I. 40%

The following graph shows the comparison of Monthly Ovitrap Index for Aedes albopictus between 2016 and average of 2000 to 2015.

Monthly Ovitrap Index

  • Please click here for graphical information on the ovitrap indices for Aedes albopictus of the year from 2004 to 2016.
  • Please click here for monthly data on the ovitrap indices for Aedes albopictus of the year from 2003 to 2016.
  • Please click here for port monthly data on the ovitrap indices for Aedes albopictus of the year from 2004 to 2016.

The Monthly Ovitrap Index for Aedes albopictus for October 2017 is 2.8%.

The Monthly Ovitrap Index for Aedes albopictus for November 2017 is not yet available. Most updated ovitrap indices

The Port Monthly Ovitrap Index for Aedes albopictus for October 2017 is 0.4%.

The Port Monthly Ovitrap Index for Aedes albopictus for November 2017 is not yet available.

Area Ovitrap Index for Aedes albopictus for all the 52 locations are shown in the following maps :

Hong Kong

Islands

Kowloon

The New Territories

Port Ovitrap Index for 6 groups of port areas are shown in the following map:

Port areas

For more details, please visit our new webpage on Dengue Fever.

 

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