Background: Diagnosis of YF is an important issue particularly in countries where it is endemic. Usual serological tests include IgM antibody capture by enzyme-linked immunosorbent assay (MAC-ELISA), hemagglutination inhibition (HI), complement fixation (CF) and neutralization (N). Nevertheless, antibody detection is feasible only 5 to 6 days after the offset of symptoms and the true usefulness is by evaluation of paired samples which are not easy to obtain. On the other hand, specific diagnosis during infection period is currently done by isolation of virus in mosquito cells or by genome detection through PCR based methods, while fatal cases are confirmed with immunohistochemistry with monoclonal antibodies over well conserved fixed tissues. Although viral isolation is a very specific technique, it takes at last 7 –10 days and sensitivity decrease when few virus particles are present in the sample or when toxic biliary salts present in serum inhibit cell growth. Detection of virus in the acute phase must be specific and sensible enough to confirm the diagnosis, and then start the surveillance measurements. Methods: Twenty five human sera were processed with the QIAamp Viral RNA Minikit. Reverse Transcription (RT) was carried out following by Polymerase Chain Reaction (PCR) using specific primers designed to amplify 734 bp from the prM/E junction. Negative samples were reamplified with internal primers (nested PCR) to obtain a 692 bp fragment. Results: The expected amplification product size was obtained in 20 of 25 samples analyzed. Positive reaction was obtained in 2 samples after first reaction, while the remaining 18 were positive after performing nested PCR. Conclusion: This improved RT-PCR using primers designed in a conserved region of genome to amplify short fragments, not just ensure detection of all YFV genotypes, but also increase sensibility even in more difficult samples. Remarkable, this reaction allows rapid differential diagnosis between Dengue and Yellow Fever, which is absolutely necessary for an effective surveillance and opportune epidemiologic measures. Abstracts for SupplementInternational Journal of Infectious DiseasesVol. 14Preview Full-Text PDF Open Archive