Comparison of three methods of collecting nasal specimens for respiratory virus analysis

Abstract

Background: Nasopharyngeal aspiration (NPA) is used widely in the collection of nasal specimens for respiratory virus diagnosis. The method has limitations in relation to technical expertise, patient anxiety, and apparatus dependence. Nasal washing (NW) offers an alternative approach. Objective: To identify the merits of two different NW methods in comparison with NPA. Design: Two hundred children with acute respiratory infection (ARI) were randomised to receive one of three collection devices: (i) standard NPA, (ii) NW using a 30ml earsyringe bulb (NWb), or (iii) NW using a 5ml syringe (NWs) with a shortened (9cm) 8FG tube. Assessment focused on ease of procedure, acceptability to parent and child, and adequacy of epithelial cell yield for immunofluorescence testing. A short questionnaire was delivered. Setting: Paediatric Ward of Kilifi District Hospital, (KDH) Kilifi, Kenya. Subjects: Any child admitted with ARI between 5th November 2001 and 24th January 2002. Results: Children recruited into NPA, NWb and NWs procedures numbered 62, 76 and 62, respectively (median age of 8 months). A higher proportion of children receiving NWb did not cry (43%) compared to those receiving NPA (13%) (OR 5.18; 95% CI 2.17-12.4). Whereas 66% of mothers were comfortable with NPA procedure, the proportion for NWs was 40% (OR 0.341; 0.163-0.714). Acceptability to the operator was marginally lower for NWs than NPA (79% vs 92%, OR 0.324, 0.107-0.974). For other observations there were no differences between the procedures; these were length of procedure (98% <5mins), the acceptable time interval for repeating a procedure (64% <1 week), comparison with blood collection (77% preferred the nasal specimen) and slides with 20 or more epithelial cells (overall 82%). Conclusion: Nasal washing methods provide simple and effective alternatives to NPA, with the NWb being the more acceptable, and have merits for use in resource poor and home settings.