Are throat swabs an acceptable specimen type for influenza testing?
Proper sample collection is vital to obtaining accurate results. It has been reported in the literature and shown in studies conducted by companies that throat swabs are the poorest specimen type for influenza testing.1,2
The adequacy of samples being tested should be carefully monitored before performing rapid tests and should be factored into interpretation of results.
Why is the design of TRU RSV® incorporating two monoclonal antibodies better than assays using just one?
Of the two monoclonal antibodies in TRU RSV®
, one is directed against a viral surface antigen and the second against nucleoprotein.3
Using multiple monoclonal antibodies directed at different viral targets improves test sensitivity.
Do you have information about the frequency of dual flu A and flu B infections?
Dual infections with other respiratory viruses have been estimated in fewer than 5% of the total number of cases. Mixed infections usually include RSV and adenovirus, or influenza A or B with one of the parainfluenza viruses. There are a few publications reporting simultaneous infection by two different strains of influenza viruses in human beings, although it is highly unlikely.4–7
Why are most rapid RSV test kits not validated for use with adults?
Adults infected with RSV shed less virus for a shorter period of time than do children.8–10
Therefore, it is often difficult to get an adequate sample from adult patients. Also, adults have drier mucosa than do children with RSV infection, thus making a less hospitable environment for survival of the virus.
1. FDA medical devices page. Food and Drug Administration Website. Available at: http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/TipsandArticlesonDeviceSafety/ucm109432.htm . Accessed August 7, 2009.
2. Covalciuc KA, Webb KH, Carlson CA. Comparison of four clinical specimen types for detection of influenza A and B viruses by optical immunoassay (FLU OIA Test) and cell culture methods. J Clin Microbiol. 1999;37:3971–3974.
3. Kim HW, Wyatt RG, Fernie BF, et al. Respiratory syncytial virus detection by immunofluorescence in nasal secretions with monoclonal antibodies against selected surface and internal proteins. J Clin Microbiol. 1983;18:1399–1404.
4. Fonseca K, Tarrant M, Lams S, Li Y. Dual infection with influenza A and B viruses. Pediatr Infect Dis J. 2002;12:795–796.
5. Toda, S, Okamoto R, Nishida T, et al. Isolation of influenza A/H3 and B viruses from an influenza patient: confirmation of co-infection by two influenza viruses. Jpn J Infect Dis. 2006;59:142–143.
6. Shimada S, Sadamasu K, Shinkai T, et al. Virological analysis of a case of dual infection by influenza A (H3N2) and B virus. Jpn J Infect Dis. 2006;59:67–68.
7. Falchi A, Arena C, Andreoletti L, et al. Dual infections by influenza A/H3N2 and B viruses and by influenza A/H3N2 and A/H1N1 viruses during winter 2007, Corsica Island, France. J Clin Virol. 2008;41:148–151.
8. Casiano-Colón AE, Hulbert BB, Mayer TK, Falsey AR. Lack of sensitivity of rapid antigen tests for the diagnosis of respiratory syncytial virus infection in adults. J Clin Virol. 2003;28:169–174.
9. Falsey AR, Walsh EE. Viral pneumonia in older adults. Clin Infect Dis. 2006;42:518–524.
10. Falsey AR, Walsh EE. Respiratory syncytial virus infection in adults. J Clin Microbiol. 2000;13:371–384.