Severe dengue virus infection in travelers: risk factors and laboratory indicators.
BACKGROUND
Dengue fever is the most common arboviral disease in travelers. In countries where dengue virus is endemic, sequential (secondary) infections with different dengue virus serotypes are associated with disease severity. Data on severity and secondary infection rates in a population of travelers are lacking.


METHODS
Intensified surveillance of dengue fever in travelers was performed within the European Network on Surveillance of Imported Infectious Diseases. Data were collected at 14 European clinical referral centers between 2003 and 2005.


RESULTS
A total of 219 dengue virus infections imported from various regions of endemicity were reported. Serological analysis revealed a secondary immune response in 17%. Spontaneous bleeding was observed in 17 (8%) patients and was associated with increased serum alanine and aspartate aminotransferase levels and lower median platelet counts. Two (0.9%) patients fulfilled the World Health Organization (WHO) case definition for dengue hemorrhagic fever. However, 23 (11%) travelers had severe clinical manifestations (internal hemorrhage, plasma leakage, shock, or marked thrombocytopenia). A secondary immune response was significantly associated with both spontaneous bleeding and other severe clinical manifestations.


CONCLUSIONS
In travelers, severe dengue virus infections are not uncommon but may be missed if the WHO classification is strictly applied. High liver enzyme levels and low platelet counts could serve as indicators of disease severity.
Wichmann
Ole
O
Institute of Tropical Medicine, Charité University Medicine, Berlin, Germany. WichmannO@rki.de
Gascon
Joaquim
J
Schunk
Mirjam
M
Puente
Sabino
S
Siikamaki
Heli
H
Gjørup
Ida
I
Lopez-Velez
Rogelio
R
Clerinx
Joannes
J
Peyerl-Hoffmann
Gabriele
G
Sundøy
Anders
A
Genton
Blaise
B
Kern
Peter
P
Calleri
Guido
G
de Górgolas
Miguel
M
Mühlberger
Nikolai
N
Jelinek
Tomas
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D000914:Antibodies, Viral / Q000097:blood; D001774:Blood Chemical Analysis; D002648:Child; D003715:Dengue / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology*; D003716:Dengue Virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D005060:Europe / Q000453:epidemiology; D005260:Female; D005843:Geography; D006470:Hemorrhage / Q000821:virology; D006760:Hospitalization; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012307:Risk Factors; D019595:Severe Dengue / Q000453:epidemiology / Q000503:physiopathology; D014195:Travel
D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M