ABSTRACT
We conducted a prospective study to measure dengue virus (DENV) antibody seroconversion in travelers to dengue-endemic areas. Travelers seen in the Boston Area Travel Medicine Network planning to visit dengue-endemic countries for ≥ 2 weeks were enrolled from 2009 to 2010. Pre- and post-travel blood samples and questionnaires were collected. Post-travel sera were tested for anti-DENV IgG by indirect IgG enzyme-linked immunosorbent assay (ELISA) and anti-DENV IgM by capture IgM ELISA. Participants with positive post-travel anti-DENV IgG or IgM were tested for pre-travel anti-DENV IgG and IgM; they were excluded from the seroconversion calculation if either pre-travel anti-DENV IgG or IgM were positive. Paired sera and questionnaires were collected for 62% (589/955) of enrolled travelers. Most participants were 19-64 years of age, female, and white. The most common purposes of travel were tourism and visiting friends and relatives; most trips were to Asia or Africa. Median length of travel was 21 days. DENV antibody seroconversion by either anti-DENV IgM or IgG ELISA was 2.9-6.8%; lower range percent excluded potential false-positive anti-DENV IgG due to receipt of yellow fever or Japanese encephalitis vaccines at enrollment; upper range percent excluded proven false-positive anti-DENV IgM. Eighteen percent of those with seroconversion reported dengue-like symptoms. Seroconversion was documented for travel to Africa as well as countries and regions known to be highly dengue endemic (India, Brazil, southeast Asia). Given widespread risk of dengue, travel medicine counseling should include information on risk of dengue in endemic areas and advice on preventing insect bites and seeking prompt medical attention for febrile illness.
Subject(s)
Dengue Virus/immunology , Dengue/blood , Seroconversion , Adolescent , Adult , Africa , Aged , Antibodies, Viral/blood , Asia , Brazil , Child , Child, Preschool , Dengue/immunology , Dengue Virus/isolation & purification , Enzyme-Linked Immunosorbent Assay , Female , Humans , Immunoglobulin G/blood , Immunoglobulin M/blood , India , Male , Middle Aged , Prospective Studies , Retrospective Studies , Surveys and Questionnaires , Travel , Vaccination , Yellow Fever/blood , Yellow Fever/immunology , Yellow Fever Vaccine/administration & dosage , Young AdultABSTRACT
We describe travelers who were evaluated pre-travel to Brazil from March 2008 through July 2010 in the Boston area. Of 599 Brazil travelers, 71%, 58%, and 50% received vaccines for yellow fever (YF), typhoid, and hepatitis A, respectively. Fewer received influenza and hepatitis B vaccines (14%, 11%). A total of 60% traveled during Brazil's peak influenza season, and one fourth visited during peak dengue transmission. The 2014 World Cup and 2016 Olympics include events throughout Brazil. Travelers should seek pre-travel assessment including YF and malaria risk; travelers should be vaccinated against influenza, be up to date on other routine vaccines, and be prepared to protect themselves against mosquitoes.