Molecular diagnosis of dengue by reverse transcriptase-polymerase chain reaction: a new tool for rapid diagnosis of dengue infection in the Caribbean

The techniques of reverse transcriptase polymerase chain reaction (RT-PCR) and subsequent PCR were employed in the analysis of serum samples from a range of patients from CAREC member countries (CMCs). Results were compared with those from viral isolation and immunofluorescence. In the second part of the study, ten serum samples were stored for one week under four sets of conditions: 20 degree C, 4 degree C, 25 degree C, and thawed (20 degree C) and frozen (-20 degree C) daily. After one week of each treatment the samples were analysed by RT-PCR and PCR. The results from PCR correlated 100 percent with results from viral isolation (VI) and fluorescent antibody (FA) detection. Where the date of onset of fever was reported, all PCR positive samples originated from sera collected within five days of this date. Frozen, refrigerated and repeated freeze thawed samples gave consistent positive results by RT-PCR. After storage at 25 degree C, however, half the dengue-positive samples were negative by RT-PCR. The results indicate the sensitivity and reliability of this rapid technique, its applicability in the Caribbean, and an idea of its limitations under certain conditions of serum collection and storage.(AU)