Effectiveness of border screening for detecting influenza in arriving airline travelers.

OBJECTIVES: We measured symptom and influenza prevalence, and the effectiveness of symptom and temperature screening for identifying influenza, in arriving international airline travelers. METHODS: This cross-sectional study collected data from travelers to Christchurch International Airport, New Zealand, in winter 2008, via a health questionnaire, temperature testing, and respiratory sampling. RESULTS: Forms were returned by 15 976 (68%) travelers. Of these, 17% reported at least 1 influenza symptom, with runny or blocked nose (10%) and cough (8%) most common. Respiratory specimens were obtained from 3769 travelers. Estimated prevalence of influenza was 1.1% (4% among symptomatic, 0.2% among asymptomatic). The sensitivity of screening criteria ranged from 84% for "any symptom" to 3% for a fever of 37.8 °C or greater. The positive predictive value was low for all criteria. CONCLUSIONS: Border screening using self-reported symptoms and temperature testing has limitations for preventing pandemic influenza from entering a country. Using "any symptom" or cough would lead to many uninfected people being investigated, yet some infected people would remain undetected. If more specific criteria such as fever were used, most infected people would enter the country despite screening.

[Effectiveness of border screening for detecting Influenza in arriving airline travelers]. / Eficacia de la detección sistemática de la gripe en las fronteras en los viajeros que llegan por vía aérea.

OBJECTIVES: We measured symptom and influenza prevalence, and the effectiveness of symptom and temperature screening for identifying influenza, in arriving international airline travelers. METHODS: This cross-sectional study collected data from travelers to Christchurch International Airport, New Zealand, in winter 2008, via a health questionnaire, temperature testing, and respiratory sampling. RESULTS: Forms were returned by 15 976 (68%) travelers. Of these, 17% reported at least 1 influenza symptom, with runny or blocked nose (10%) and cough (8%) most common. Respiratory specimens were obtained from 3769 travelers. Estimated prevalence of influenza was 1.1% (4% among symptomatic, 0.2% among asymptomatic). The sensitivity of screening criteria ranged from 84% for "any symptom" to 3% for a fever of 37.8 ºC or greater. The positive predictive value was low for all criteria. CONCLUSIONS: Border screening using self-reported symptoms and temperature testing has limitations for preventing pandemic influenza from entering a country. Using "any symptom" or cough would lead to many uninfected people being investigated, yet some infected people would remain undetected. If more specific criteria such as fever were used, most infected people would enter the country despite screening.

Effectiveness of border screening for detecting influenza in arriving airline travelers.

OBJECTIVES: We measured symptom and influenza prevalence, and the effectiveness of symptom and temperature screening for identifying influenza, in arriving international airline travelers. METHODS: This cross-sectional study collected data from travelers to Christchurch International Airport, New Zealand, in winter 2008, via a health questionnaire, temperature testing, and respiratory sampling. RESULTS: Forms were returned by 15 976 (68%) travelers. Of these, 17% reported at least 1 influenza symptom, with runny or blocked nose (10%) and cough (8%) most common. Respiratory specimens were obtained from 3769 travelers. Estimated prevalence of influenza was 1.1% (4% among symptomatic, 0.2% among asymptomatic). The sensitivity of screening criteria ranged from 84% for "any symptom" to 3% for a fever of 37.8 °C or greater. The positive predictive value was low for all criteria. CONCLUSIONS: Border screening using self-reported symptoms and temperature testing has limitations for preventing pandemic influenza from entering a country. Using "any symptom" or cough would lead to many uninfected people being investigated, yet some infected people would remain undetected. If more specific criteria such as fever were used, most infected people would enter the country despite screening.

Screening for influenza infection in international airline travelers.

We sought the collaboration of an international airline and border control agencies to study the feasibility of entry screening to identify airline travelers at increased risk of influenza infection. Although extensive and lengthy negotiations were required, we successfully developed a multisector collaboration and demonstrated the logistical feasibility of our screening protocol. We also determined the staffing levels required for a larger study to estimate the prevalence of influenza in international airline travelers.

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.

Thermal image scanning for influenza border screening: results of an airport screening study.

BACKGROUND: Infrared thermal image scanners (ITIS) appear an attractive option for the mass screening of travellers for influenza, but there are no published data on their performance in airports. METHODS: ITIS was used to measure cutaneous temperature in 1275 airline travellers who had agreed to tympanic temperature measurement and respiratory sampling. The prediction by ITIS of tympanic temperature (37.8°C and 37.5°C) and of influenza infection was assessed using Receiver Operating Characteristic (ROC) curves and estimated sensitivity, specificity and positive predictive value (PPV). FINDINGS: Using front of face ITIS for prediction of tympanic temperature ≥37.8°C, the area under the ROC curve was 0.86 (95%CI 0.75-0.97) and setting sensitivity at 86% gave specificity of 71%. The PPV in this population of travellers, of whom 0.5% were febrile using this definition, was 1.5%. We identified influenza virus infection in 30 travellers (3 Type A and 27 Type B). For ITIS prediction of influenza infection the area under the ROC curve was 0.66 (0.56-0.75), a sensitivity of 87% gave specificity of 39%, and PPV of 2.8%. None of the 30 influenza-positive travellers had tympanic temperature ≥37.8°C at screening (95%CI 0% to 12%); three had no influenza symptoms. CONCLUSION: ITIS performed moderately well in detecting fever but in this study, during a seasonal epidemic of predominantly influenza type B, the proportion of influenza-infected travellers who were febrile was low and ITIS were not much better than chance at identifying travellers likely to be influenza-infected. Although febrile illness is more common in influenza A infections than influenza B infections, many influenza A infections are afebrile. Our findings therefore suggest that ITIS is unlikely to be effective for entry screening of travellers to detect influenza infection with the intention of preventing entry of the virus into a country.

Eficacia de la detección sistemática de la gripe en las fronteras en los viajeros que llegan por vía aérea / Effectiveness of border screening for detecting Influenza in arriving airline travelers

OBJETIVOS: Se midieron los síntomas y la prevalencia de la gripe (también llamada influenza), así como la eficacia del mecanismo de detección sistemática basado en los síntomas y la temperatura para diagnosticar la gripe en viajeros internacionales que llegaban por vía aérea. MÉTODOS: El presente estudio transversal recopiló datos de viajeros que llegaron al aeropuerto internacional de Christchurch (Nueva Zelandia) en el invierno del 2008 mediante un cuestionario de salud, medición de la temperatura y toma de muestras de las vías respiratorias. RESULTADOS: De los viajeros, 15 976 (68%) entregaron los formularios completos. De ellos, 17% notificaron al menos un síntoma de gripe; los síntomas más comunes fueron rinorrea o congestión nasal (10%) y tos (8%). Se tomaron muestras de las vías respiratorias de 3 769 viajeros. La prevalencia estimada de la gripe fue de 1,1% (4% en las personas sintomáticas, 0,2% en las asintomáticas). La sensibilidad de los criterios de detección varió de 84% para "cualquier síntoma" a 3% para la fiebre de 37,8 ºC o mayor. El valor predictivo positivo fue bajo para todos los criterios. CONCLUSIONES: El método de detección sistemática en las fronteras mediante la autonotificación de síntomas y la toma de la temperatura presenta limitaciones para impedir que una gripe pandémica entre en un país. Basarse en criterios como "cualquier síntoma" o la tos haría que se investigara a varias personas no infectadas, mientras que algunas personas infectadas pasarían inadvertidas. Si se usaran criterios más específicos como la fiebre, la mayoría de las personas infectadas entrarían en el país a pesar del mecanismo de detección.

ABSTRACT OBJECTIVES: We measured symptom and influenza prevalence, and the effectiveness of symptom and temperature screening for identifying influenza, in arriving international airline travelers. METHODS: This cross-sectional study collected data from travelers to Christchurch International Airport, New Zealand, in winter 2008, via a health questionnaire, temperature testing, and respiratory sampling. RESULTS: Forms were returned by 15 976 (68%) travelers. Of these, 17% reported at least 1 influenza symptom, with runny or blocked nose (10%) and cough (8%) most common. Respiratory specimens were obtained from 3769 travelers. Estimated prevalence of influenza was 1.1% (4% among symptomatic, 0.2% among asymptomatic). The sensitivity of screening criteria ranged from 84% for "any symptom" to 3% for a fever of 37.8 ºC or greater. The positive predictive value was low for all criteria. CONCLUSIONS: Border screening using self-reported symptoms and temperature testing has limitations for preventing pandemic influenza from entering a country. Using "any symptom" or cough would lead to many uninfected people being investigated, yet some infected people would remain undetected. If more specific criteria such as fever were used, most infected people would enter the country despite screening.