Recognising risk factors associated with JE
The risk of JE infection is present from the moment a traveller enters an area where the disease is endemic. Notably, over a third of reported JE cases occur in travellers on short trips, lasting less than one month.1,2

Global warming poses an increasing threat to public health, including a heightened risk of mosquito-borne diseases like JE. Rising temperatures create more favourable breeding conditions for mosquitoes, potentially expanding their geographic range and increasing their activity.3 In temperate areas of Asia, JEV is transmitted mostly during the warm season, whereas in the tropics and subtropics, transmission can occur year-round but often intensifies during the rainy season.4
While JE is traditionally associated with rural environments, evidence suggests that transmission is also occurring in urban areas of Southeast Asia. This highlights the importance of considering vaccination for travellers whose itineraries include both rural and urban destinations.5,6 Travellers with flexible or unplanned itineraries may also be at higher risk of JE, particularly if their activities could lead to increased exposure to mosquitoes.7
Vaccination: a critical defence against JE
Vaccination is strongly recommended for individuals travelling to areas where JE is endemic. This includes people relocating to these areas, long-term travellers (one month or longer), and shorter-term travellers whose itineraries and activities place them at a higher risk of exposure to infected mosquitoes (e.g. spending time in rice fields or close to pig farms).8
Pharmacists are vital in educating travellers about JE and emphasising the significance of vaccination. This includes providing clear and concise information about the disease, its transmission, risk factors, and the potential benefits and risks of vaccination. It is crucial to discuss all of this with travellers to help them make informed decisions about vaccination. While the overall risk of JE infection is relatively low, the potential for severe complications and long-term disabilities underscores the importance of preventive measures.9
References
- Buhl MR, et al. J Travel Med. 2009;16:217–219.
- Pavli A, et al. J Infect Dev Ctries. 2015;9:917-924.
- Tian HY, et al. Environ Int. 2015;79:17-24.
- World Health Organization. Japanese encephalitis. August 2024. Available at: www.who.int. Accessed December 2024.
- Murty US, et al. J Vector Borne Dis. 2010;47:26-32.
- Lindahl JF, et al. PLoS Negl Trop Dis.2013;7:e2153.
- Centers for Disease Control and Prevention. Yellow Book 2024. Section 5 Travel-Associated Infections & Diseases. May 2023. Available at: wwwnc.cdc.gov. Accessed December 2024.
- UK Health Security Agency (UKHSA). Chapter 20: Japanese encephalitis. February 2024. Available at: travelhealthpro.org.uk. Accessed December 2024.
- Centers for Disease Control and Prevention. Japanese encephalitis vaccine: Recommendations of the Advisory Committee on Immunization Practices. MMWR Morb Mortal Wkly Rep 2019;68(2):1–33. Available at: www.cdc.gov. Accessed December 2024.
Adverse events should be reported.
Reporting forms and information can be found at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. Adverse events should also be reported to the Valneva UK Ltd Medical Information department on Tel: 01506 446608 or via email: safety@valneva.com
Reporting forms and information can be found at www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. Adverse events should also be reported to the Valneva UK Ltd Medical Information department on Tel: 01506 446608 or via email: safety@valneva.com