Respiratory viruses in airline travellers with influenza symptoms: Results of an airport screening study

BACKGROUND: There is very little known about the prevalence and distribution of respiratory viruses, other than influenza, in international air travellers and whether symptom screening would aid in the prediction of which travellers are more likely to be infected with specific respiratory viruses. OBJECTIVES: In this study, we investigate whether, the use of a respiratory symptom screening tool at the border would aid in predicting which travellers are more likely to be infected with specific respiratory viruses. STUDY DESIGN: Data were collected from travellers arriving at Christchurch International Airport, New Zealand, during the winter 2008, via a symptom questionnaire, temperature testing, and respiratory sampling. RESULTS: Respiratory viruses were detected in 342 (26.0%) of 1313 samples obtained from 2714 symptomatic travellers. The most frequently identified viruses were rhinoviruses (128), enteroviruses (77) and influenza B (48). The most frequently reported symptoms were stuffy or runny nose (60%), cough (47%), sore throat (27%) and sneezing (24%). Influenza B infections were associated with the highest number of symptoms (mean of 3.4) followed by rhinoviruses (mean of 2.2) and enteroviruses (mean of 1.9). The positive predictive value (PPV) of any symptom for any respiratory virus infection was low at 26%. CONCLUSIONS: The high prevalence of respiratory virus infections caused by viruses other than influenza in this study, many with overlapping symptotology to influenza, has important implications for any screening strategies for the prediction of influenza in airline travellers.