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Published on: December 29, 2015
Japanese encephalitis virus genotype III from mosquitoes in Tarlac, Philippines
Wilfredo E Aure1,2, Yusuke Sayama3, Mariko Saito-Obata3,4
1Department of Medical Entomology, Research Institute for Tropical Medicine, Filinvest Corporate City, Alabang, Muntinlupa City, Metro Manila, Philippines, 1781.
Objectives:
The aim of this study was to investigate the presence of Japanese encephalitis virus (JEV) in a rice-farming community in the Philippines and to determine its implications regarding the epidemiology of viral encephalitides in the Asia-Pacific Region.
Methods:
Mosquitoes were collected monthly from animal-baited traps close to flooded rice fields in two barangays (villages) in the Municipality of San Jose, Tarlac Province in Luzon, from May 2009 to July 2010. Virus was detected by nested reverse transcription PCR. Phylogenetic analysis of the amplified virus envelope gene was done using the maximum-likelihood method.
Results:
A total of 28 700 known vector mosquitoes were collected, namely Culex vishnui, Culex fuscocephala, Culex tritaeniorhynchus, and Culex gelidus. JEV genotype III was detected in C. tritaeniorhynchus, belonging to the same genotype but form a different clade from those reported in the 1980s and in 2020 in this country.
Conclusions:
Japanese encephalitis is associated with rice cultivation and the presence of infected mosquitoes in Tarlac, Philippines. It remains to be seen whether the observed genetic shift of genotype III to genotype I in Asia will in time have an impact on the epidemiology of Japanese encephalitis in the Philippines. For long-term disease control, regular surveillance and Japanese encephalitis immunization in children and travelers in high risk areas are recommended.
Insights
Japanese encephalitis virus (JEV) was detected in mosquitoes in a Philippine rice-farming community. This highlights the need for ongoing surveillance and vaccination to control JEV, especially considering potential genetic shifts.
Area of Science:
- Medical Entomology
- Virology
- Epidemiology
Background:
- Japanese encephalitis (JE) is a significant cause of viral encephalitis in the Asia-Pacific region.
- Rice cultivation is a known risk factor for JE transmission due to its association with mosquito vectors.
Purpose of the Study:
- To investigate the presence of Japanese encephalitis virus (JEV) in a Philippine rice-farming community.
- To assess the implications of JEV findings on the epidemiology of viral encephalitides in the Asia-Pacific.
Main Methods:
- Mosquitoes were collected monthly from May 2009 to July 2010 in Tarlac Province, Philippines.
- Virus detection was performed using nested reverse transcription PCR.
- Phylogenetic analysis of the virus envelope gene was conducted using the maximum-likelihood method.
Main Results:
- Over 28,700 mosquitoes, including *Culex vishnui*, *Cx. fuscocephala*, *Cx. tritaeniorhynchus*, and *Cx. gelidus*, were collected.
- Japanese encephalitis virus (JEV) genotype III was identified in *Cx. tritaeniorhynchus*.
- The detected JEV genotype III formed a distinct clade compared to previous strains in the Philippines.
Conclusions:
- Japanese encephalitis is linked to rice farming and infected mosquitoes in Tarlac, Philippines.
- The potential impact of a genetic shift from JEV genotype III to genotype I on Philippine epidemiology requires further monitoring.
- Long-term control strategies should include regular surveillance and JEV immunization for at-risk populations.
