Background: Dengue virus (DENV) infection is increasing in prevalence and severity globally. The severity of dengue is influenced by several factors including the immune response, viral and host genetic factors.
Method: The DENV serotypes were determined in 770 serum samples from dengue immunoglobulin (Ig) M antibody positive (n = 469), dengue IgM negative (n = 185) and dengue antibody negative (n = 116) patients with suspected dengue who presented during (n = 150) or after (n = 620) the acute phase of illness during 2003−2007. Dengue antibodies were detected by enzyme-linked immunosorbent assays and DENV RNA by reverse transcriptase-polymerase chain reaction (RT-PCR) performed on serum and cell culture supernatants of C6/36 mosquito cells inoculated with acute phase serum (n = 150).
Results: Based on serological profiles, 41% of acute phase sera and 66% of post acute sera were from patients with current primary or secondary dengue, while 41% and 35% of acute and post-acute phase sera, respectively, were from patients with secondary dengue or past exposure only. Dengue virus RNA was found in 20/770 samples (2.6%). Only 1.5% (9/620) of sera collected after the acute phase of illness tested positive for DENV RNA compared with 2.6% (4/150) of sera collected during the acute phase and 7.3% of cell culture supernatants inoculated with acute phase serum (11/150, p = 0.001). All four serotypes including DENV-1 (3/20, 15%), DENV-2 (7/20, 35%), DENV-3 (3/20, 15%) and DENV-4 (7/20, 35%) were identified over the five-year period. These results also showed that DENV-1, 2 and 4 were present during 2007 and that DENV-2 and DENV- 4 were the likely causative viruses of the 2007−2008 dengue outbreak in Jamaica. The three strains of DENV-3 were isolated from infants less than three years of age with primary infection during 2006.
Conclusion: This study highlights the increasing threat of dengue and severe dengue disease to the Jamaican population. Preventative measures including laboratory surveillance and vector control should be strictly maintained at the highest level.