Japanese Encephalitis in Travelers from Non-Endemic Countries, 1973–2008

Abstract

Japanese encephalitis (JE) is a severe disease and a risk for travelers who visit JE-endemic countries. We reviewed all published JE cases in travelers from non-endemic areas from 1973 through 2008, and assessed factors related to risk of infection. There were 55 cases that occurred in citizens of 17 countries. Age range of case-patients was 1–91 years (median = 34 years). Ten (18%) persons died and 24 (44%) had mild to severe sequelae. In a detailed risk assessment of 37 case-patients, 24 (65%) had spent ≥ 1 month in JE-endemic areas, and most had factors identified that may have increased infection risk. The estimate of overall JE risk was low, < 1 case/1 million travelers to JE-endemic countries. Nonetheless, for each traveler, a careful assessment of itinerary and activities, a decision on vaccination, and information on mosquito precautions are needed to reduce the risk of this disease.

Japanese Encephalitis, Recent Perspectives on Virus Genome, Transmission, Epidemiology, Diagnosis and Prophylactic Interventions

“…The occurrence of symptomatic to asymptomatic infection ratio is 1: 25-1000 (1:300 on an average) (Saxena & Dhole, 2008). The incubation period ranges between 5 and 15 days, and symptoms are pyrexia, chillness, lethargy, muscle ache, headache, abdominal pain and vomition (Hills et al, 2010).…”

“…Vaccination of people living in endemic areas, lab personnel with a possible for JEV exposure, travellers staying for more than one month in the prevalent zone and also to travellers staying less than a month during the JE transmission season is the reliable strategy for the prevention of JE (Fischer et al, 2010). At present, inactivated mouse brain-derived (Nakayama and Beijing-1) and Vero cell-based inactivated (Beijing-1, P-3, SA 14-14-2, Kolar strain-JEV 821564XY) vaccines are available.…”

“…About 3 doses (0, 7 and 14/30 days) of vaccine along with one booster after one year and thereafter every 3 years until age 10 years are recommended (Malhotra et al, 2015). Although the vaccine is safe and effective, about 20 % of the vaccinated people may develop local adverse reactions such as pain, swelling, and redness while 10 % of people may suffer from common side effects like pyrexia, chillness, headache, rashes and myalgia (Fischer et al, 2010;Lindsey et al, 2010). Rarely, hypersensitivity due to the presence of thimerosal was reported which hampers the use of the vaccine in the rural areas, where the vaccine is immediately required (CDC, 2011).…”

Product review on the JE vaccine IXIARO

“…54 In a recent review of JE cases in travelers, a detailed risk assessment of 37 cases revealed that 35% had spent less than 1 month in JE-endemic areas and thus would not have been recommended vaccination. 55 Nonetheless IXIARO Ò provides proven protection with a favorable safety profile and outdated guidelines and recommendations should be revised according to an expert recommendation: travelers to rural areas of Asia should generally be recommended vaccination. 56 For travelers, a primary immunization regimen of 28 d can take too long to complete before departure.…”

Prevention, diagnosis, and management of Japanese encephalitis in children

“…According to the Centers for Disease Control and Prevention, USA, JE occurs in less than one case per million travelers to Asia 26 and from 1973 to 2001, only 58 cases of JE have been reported among travelers from non-endemic countries. 27 Risk is likely to be higher if the period of stay in the endemic region is longer and if involved in outdoor activities in rural areas. 28,29 Assuming an annual incidence of ten per 1,000 in the region being visited, the risk of developing the disease during a month long visit during the transmission season came to one per 5,000.…”