1. Immunization of travelers against japanese encephalitis Dr Catherine Goujon Centre médical de l’Institut Pasteur

2. Immunization of travelers against japanese encephalitis

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1. The disease
Arthropod borne virus genus Flavivirus transmitted by mosquito of Culex species with nocturnal activity Transmission occurs in rural areas with rice cultivation and flood irrigation.
Anthropozoonosis

4. Immunization of travelers against japanese encephalitis
2. Epidemiology
The most common cause of viral encephalitis in Asia*
Incidence : 68 000 cases/year, i.e. 8,2 /100  à deceases per year Predominance : children < 15 years old.
*WHO Fact sheet No 386 December 2015

5. Immunization of travelers against japanese encephalitis
2. Epidemiology*
Seasonal transmission in temperate areas : peaks in summer and fall ;
Seasonal transmission in sub tropical areas, varies with monsoon rain and irrigation practices ;
Year-round transmission in tropical areas. *

6. Immunization of travelers against japanese encephalitis
3. Clinical features
Frequently asymptomatic ;
Severe encephalopathy : 1 case / 250 ;
case-fatality rate : 40% à 60% ;
permanent neurologic and psychiatric sequelae : case /3 ;
No specific treatment.
4. Prevention
Protection against mosquito bites ;
Vaccination.

7. Immunization of travelers against japanese encephalitis
5. Estimated risk of infection for a non immunised traveler
Very low : from 1/ to 1/5000 per week of stay, (79 cases notified from 1973 to 2015 among non immunized travelers or expatriates - CDC Yellow Book), but unpredictable.
Japanese encephalitis in a Danish short-term traveler to Cambodia. J Travel Med. 2011;18(6): Fatal Japanese encephalitis in a Danish tourist visiting Bali for 12 days. Scand J Infect Dis. 1996;28(2):189.

8. Immunization of travelers against japanese encephalitis
6. Indications of vaccination among traveler
French Health recommendations for travelers
Stay (whatever duration) with outside exposure in an endemic region, particularly in rural areas ;
Expatriation in a country located in a virus circulation area ;
Any other situation estimated at risk by the medical practitionner.

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7. Vaccines
Table of JE Vaccines Appendix 4 -
Background paper on japanese encephalitis vaccies
Prepared by the SAGE Working Group on Japanese encephalitis vaccine October 1, 2014

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7.2. Ixiaro® vaccine
Classic schedule adults, children  2 months of age :
2 doses at day 0 and day 28 (1/2 dose < 3 years of age) ;
- 1st booster 12 to 24 months after primary dose, before new exposure to JE virus (12 months in case of continuous exposure) ;
2nd booster adults years of age : 10 years later (based on data of long term seroprotection).
Accelerated schedule adults years of age :
2 doses at day 0 and day 7.

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7.3. Ixiaro® accelerated schedule
Phase III study :
217 subjects years old : doses at day 0 and day rabies vaccine ;
56 controls : classic schedule day 0-day 28.
Seroconversion rate and 28 days after 2nd injection : similar with both schedules.
Seroconversion rate and antibody titers stayed high as long as 12 mois after 1st immunisation with both schedules.
Jelinek T, Burchard GD, Dieckmann S, Buhler S, Paulke-Korinek M, Nothdurft HD, et al. Short-Term immunogenicity and safety of an accelerated preexposure prophylaxis regimen with Japanese encephalitis vaccine in combination with a rabies vaccine: a phase III, multicenter, observer-blind study. J Travel Med Jul-Aug;22(4):225–31.

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7.3. Accelerated schedule
Not approved for other age categories :
adults > 65 years of age, children < 18 years of age, since
- no study on accelerated schedule ;
- no data on long term seroprotection.
It would be desirable however that last minute-travelers of these age categories may be immunized as well against Japanese encephalitis, when they are visiting endemic areas.

13. Thank you for your attention