Comparative study of Rapid Test with Standard Method RT-PCR for Detection of Influenza A virus infection in Suspected Cases Admitted at Khon Kaen Hospital during 2005-2007

ABSTRACT

Avian influenza (Bird flu), an acute respiratory tract infection caused by influenza virus type A. Recently reported H5N1 flu virus strain may have been transmitted directly from birds to humans. The acute respiratory distress syndrome (ARDS) caused by avian influenza H5N1 viral infection has been one of the most important reasons for patient death. To control disease outbreaks and earlier patient treatment the rapid and accurate detection are the important factors. Recently, rapid test has been widely used as a tool for the screening of avian flu because it provides rapid detection. The aim of this work was to assess the performance and effectiveness of rapid test; Clearview Exact Influenza A\&B for detection of influenza A virus in nasopharygneal swab were collected from patients with influenza-like illness admitted in Khon Kaen Hospital by using RT-PCR as the reference method. The prevalences of Influenza A positive in 50 cases measured by rapid test and RT-PCR are 23.8% and 66.7%. The Sensitivity, Specificity, Positive predictive value, Negative predictive value and Prevalence are 83.33% (95%CI 51.5-91.9), 100% (95%CI 88.4-100), 100% (95%CI 69.1-100), 93.75% (95%CI 79.2-99.2) and 28.57% (95%CI 15.7-44.6) respectively. The finding that the sensitivity of rapid test was slightly low when compared with standard method RT-PCR. There may dependent on many factors including the method of specimen collection, the test method used, geographic location, and the disease prevalence in specific localities. In addition, the important properties of diagnostic tests that need to considered are analytical sensitivity and analytical specificity.