Hepatitis A virus infections in travelers, 1988-2004.
BACKGROUND
Uncertainty exists about the current risk of hepatitis A virus infection in nonimmune travelers to destinations with high or intermediate risk of transmission. We analyzed recent epidemiological data on imported hepatitis A to determine region-specific attack rates and incidences.


METHODS
Surveillance data on hepatitis A virus infections diagnosed during 1988-2004 were evaluated on the basis of notification by laboratories, additional reports of physicians, and traveler's statistics. This study focuses on international travelers with hepatitis A virus infection detected after their return to Switzerland.


RESULTS
The rate of imported hepatitis A virus infections decreased 75% from 1988 to 2004 and accounted overall for 42% of all hepatitis A cases reported in Switzerland. The actual incidence of hepatitis A in travelers to countries of high or intermediate risk of transmission was 3.0-11.0 per 100,000 person-months abroad for all travelers and 6.0-28.0 per 100,000 for those presumed to be nonimmune. The actual proportion of those visiting friends and relatives among patients with hepatitis A has increased to 28.2%, with children aged 0-14 years predominating. Reductions in the incidence by hepatitis A vaccination were estimated to vary between 35.0% and 61.8% for different destinations.


CONCLUSIONS
The risk of hepatitis A virus infections has decreased by a factor of 10-50-fold over time, compared with findings from older studies. The risk, however, remains very considerable at many destinations, including frequently visited places, such as Mexico. Children of immigrants are a high-risk population. Strategies are needed to reach those at highest risk.
Mutsch
Margot
M
Division of Epidemiology and Prevention of Communicable Diseases, World Health Organization Collaborating Centre for Travelers' Health, Institute of Social and Preventive Medicine, University of Zurich, Zurich, Switzerland. muetsch@ifspm.unizh.ch
Spicher
Virginie Masserey
VM
Gut
Christoph
C
Steffen
Robert
R
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003906:Developing Countries; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control / Q000635:transmission; D022362:Hepatitis A Vaccines / Q000008:administration & dosage; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012306:Risk; D018709:Statistics, Nonparametric; D013557:Switzerland / Q000453:epidemiology; D014195:Travel
D022362:Hepatitis A Vaccines