Dengue Virus Seroconversion in Travelers to Dengue-Endemic Areas

Abstract

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 dengueendemic 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. BACKGROUND

Seroprevalence of Hepatitis E Among Boston Area Travelers, 2009–2010

“…The second was a dengue seroconversion study with an enrollment period of January 2009 to September 2010. 17 To be eligible for enrollment in the seroconversion study, participants must have indicated that they would be available to return for follow-up after travel.…”

The older traveller

“…DHF and DSS usually affect children living in endemic areas and infrequently adults, especially travellers [41]. In the study performed by Rowe et al [42], 4.4% of the 6989 cases were found in patients aged 60 or older, although in other studies the prevalence of dengue in patients older than 65 years ranged between 4.2% and 8.7% [43,44]. Although the number of cases in the elderly is relatively low, a Taiwanese study showed that 69.9% of all patients hospitalised for dengue and 85.3% of dengue patients admitted to intensive care units were over 60 [45].…”

Risk of Dengue in Travelers: Implications for Dengue Vaccination

“…Prospective studies are better suited to determine the attack rate than sentinel surveillance. A dengue antibody seroconversion study in travelers with a median length of travel of 21 days seen in the Boston Area Travel Medicine Network found a seroconversion rate by either anti-DENV IgM or IgG ELISA between 2.9 and 6.8% [34]. Eighteen percent of those with seroconversion reported dengue-like symptoms.…”

“…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) [34]. In Swedish travelers, an increasing trend of dengue infections over time was found for most destinations [35•].…”