Japanese encephalitis (JE), a mosquito-borne viral disease in humans and animals, is a major public health problem in east and southeastern Asia. People get JE by the bite of mosquitoes infected with the virus. Mosquitoes become infected when feeding on infected animals, in most cases domestic pigs and wild birds, and then transmit the disease to humans and other animals during the feeding process. Sporadic cases of JE occurred locally very infrequently in past decades.
The vectors responsible for the transmission of JE are mainly Culex mosquitoes including Culex tritaeniorhynchus, Culex gelidus and Culex fuscocephala. In China and many endemic areas in Asia, Culex tritaeniorhynchus is the principal vector. This species feeds outdoors beginning at dusk and during evening hours until dawn. Larvae are mostly found in flooded rice fields, water-lodged abandoned fields, marshes and small stable collections of water around cultivated fields. The other two species are also known to occur in Hong Kong. Their local favourable breeding habitats are weedy grounds with moderate degree of pollution for Culex gelidus and water storage pits, irrigation ditches and rice fields for Culex fuscocephala.
FEHD had carried out a territory-wide survey on Japanese Encephalitis vector in 2005 to update the information on their distribution. Adult trappings were conducted in areas within 2km radius from pig farms, slaughter houses and sites with aggregation of migratory birds. Larval surveys were also conducted in illegal cultivation and vacant sites.
The following map shows the findings of Japanese Encephalitis vector in October 2005
Please click here for information on the findings of Japanese Encephalitis vector since October 2004.
1. Source reduction / Elimination of breeding place