Trends in the patterns of IgM and IgG antibodies in febrile persons with suspected dengue in Barbados, an English-speaking Caribbean country, 2006–2013

Long-term seroprevalence studies of dengue have provided a measure of the degree of endemicity and future trends in disease prevalence and severity. In this study, we describe the seroprevalence of dengue antibodies in febrile persons with suspected acute dengue in Barbados. It is a retrospective population-based study of all febrile persons with suspected dengue from 2006 to 2013. All of the cases had IgM and IgG antibodies in the blood sample drawn between days 3 and 5 of their illness. Among the 8296 cases that were tested for IgM antibodies, 3037 [36.6%] had recent dengue infection. In the age groups <5 years, 5-20 years and >20 years, 23.3%, 39.6% and 35.5% had acute infection, respectively. Of the 7227 cases with documented IgG results, 5473 [75.7%] were positive and had a past infection. In the age groups <5 years, 5-20 years and >20 years, 31.2%, 65.2% and 86.6%, respectively, had a past infection [IgG positive]. During the first 5 years of life, 10-20% of febrile persons investigated for dengue had a positive IgM and a negative IgG titer, between 5 and 10% had a positive IgM and IgG titer, 5% had a positive IgG and a negative IgM titer, and between 45% and 65% had a negative IgM and a negative IgG titer. Throughout the study period, between 12% and 20% of febrile persons failed to show any evidence of current or previous dengue. In the age groups <5 years, 5-20 years and >20 years, 45.0%, 18.8% and 7.2%, respectively, had no evidence of recent or past dengue [both IgM and IgG negative]. Between 37% and 59% of the febrile persons had serological evidence of past dengue in the absence of any current dengue. In conclusion, the pattern of IgG antibodies in this study was comparable to those in countries known to be hyperendemic for dengue. The age of infection is likely to shift to younger adults and children who are more likely to have severe dengue in the future