Prevalence of anti-dengue immunoglobulin G antibodies among American Red Cross blood donors in Puerto Rico, 2006.

BACKGROUND

Dengue is endemic in Puerto Rico and causes periodic outbreaks involving thousands of persons. Seroprevalence studies among blood donors can provide useful data on the immune status of the adult population. The objective of this study was to determine the prevalence of anti-dengue immunoglobulin (Ig)G antibodies in a random sample of blood donors to the American Red Cross (ARC) in Puerto Rico.

STUDY DESIGN AND METHODS

Three-hundred randomly selected blood donations collected by the ARC from February 1 to March 31, 2006, were tested using an anti-dengue IgG enzyme-linked immunosorbent assay. One-third of the positive specimens were randomly selected and tested by a microneutralization test (MNT) to determine the serotypes of previous dengue infections.

RESULTS

Most (84%) blood donors were male, and the mean age was 44.6 years (range, 18-80 years). The prevalence (95% confidence interval) of anti-dengue IgG antibodies was 92% (89%-95%). Of the 92 specimens tested by the MNT, reactivity to all four dengue serotypes was observed and 96% were secondary infections. The predominant serotype with the highest neutralization titers, as identified by at least a fourfold higher titer compared to any other serotype tested, was identified in 32 specimens; the most common predominant serotypes identified by the MNT were DENV-3 and DENV-2 (63%). Recent infection with DENV-1 was detected but, in 2005, routine surveillance did not detect any cases of this serotype.

CONCLUSION

Supplementary serologic testing of donated blood can potentially provide information on the silent circulation or introduction of dengue serotypes.