|A.||Viral culture of nasopharyngeal specimen|
Influenza A enzyme immunoassay antigen detection on throat specimen
Influenza A direct fluorescent antibody on nasopharyngeal specimen
Influenza A IgG serology on acute serum
Ans: C, Influenza A direct fluorescent antibody on nasopharyngeal specimen
The rapid antigen tests commercially available for identification of influenza A or B have variable sensitivity and specificity compared to viral culture.
The direct fluorescent antibody is more sensitive than the rapid antigen tests, and its sensitivity is high (90%) when compared with culture.
Serologic testing with acute and convalescent serum can identify children with influenza not detected by other methods but is not helpful for rapid diagnosis. According to the Centers for Disease Control and Prevention, “During periods when influenza activity is high and influenza viruses are circulating among persons in the community, the positive predictive value of a test result is high”