Encephalitis in travellers: a prospective multicentre study

Abstract

Background: As the epidemiology of encephalitis varies from one country to another, international travel may be an important clue for the diagnostic workout of this puzzling disease.

Methods: We performed an ancillary study using the ENCEIF prospective cohort conducted in 62 clinical sites in France from 2016 to 2019. All cases of encephalitis in adults that fulfilled a case definition derived from the International Encephalitis Consortium were included. Travellers were defined as patients who spent at least one night in a foreign country within the last six months.

Results: Of the 494 encephalitis patients enrolled, 69 (14%) were travellers. As compared to non-travellers, they were younger (median age, 48 years [interquartile range, 36-69] vs 66 [49-76], P < 0.001), less likely to be immunocompromised: 2/69 (3%) vs 56/425 (13%), P = 0.02, and reported more arthralgia: 7/69 (10%) vs 11/425 (3%), P = 0.007. The risk of poor outcome at hospital discharge (Glasgow outcome scale ≤3), was similar for travellers and for non-travellers after adjustment (aOR 0.80 [0.36-1.80], P = 0.594). Arboviruses were the main causes of encephalitis in travellers: 15/69 (22%) vs 20/425 (5%) in non-travellers, P < 0.001, and Herpes simplex virus (HSV) was the second (9/69, 13%). Of note, in 19% (13/69) of cases, the risk of encephalitis in travellers may have been decreased with a vaccine.

Conclusion: The two primary causes of encephalitis in travellers are arboviruses and HSV. Empirical treatment of encephalitis in travellers must include acyclovir. Pre-travel advice and vaccination may decrease the risk of encephalitis in travellers.

Keywords: Encephalitis; arbovirus; herpes simplex virus; prevention; travellers.