Abstract

Introduction: The specific diagnosis of influenza A infection makes it possible to control its spread, decreases the unnecessary use of antibiotics, clinical procedures and laboratory test, and allows early recognition of outbreaks. Different technologies are currently available in Chile for this purpose. Objective: The study presented here compares the sensitivity for influenza A virus detection of immunocromatography (RIDT), direct fluorescent antibodies-DFA and DFA with cytocentrifugation against the gold standard, RT-PCR. Material and Methods: In 175 nasal swab samples influenza A RIDT and RT-PCR were performed. Another 1689 nasal swab samples were tested by DFA and RT-PCR for influenza A. Finally, 29 nasal swab samples confirmed as Influenza A positive by RT-PCR were tested by DFA with cytocentrifugation. Results: The RIDT, DFA and DFA + cytocentrifugation sensitivity was 47,3%, 57,2% and 72,4%, respectively. Discussion and Conclusion: Their lower cost and faster turnaround time when compared to PCR make RIDT and DFA the tests of choice in diagnostic laboratories in Chile. However, their low sensitivity and NPV, especially during low season, makes more sensitive diagnostic tools necessary to confirm the results. In our study cytocentrifugation increased DFA sensitivity from 57% to 72%.