Syndromic recognition of influenza A infection in a low prevalence community setting.
BACKGROUND
With epidemics of influenza A virus infection, people and medical professionals are all concerned about symptoms or syndromes that may indicate the infection with influenza A virus.


RESULTS
A prospective study was performed at a community clinic of a metropolitan area. Throat swab was sampled for 3-6 consecutive adult patients with new episode (<3 days) of respiratory tract infection every weekday from Dec. 8, 2005 to Mar. 31, 2006. Demographic data, relevant history, symptoms and signs were recorded. Samples were processed with multiplex real time PCR for 9 common respiratory tract pathogens and by virus culture. Throat swab samples were positive for Influenza A virus with multiplex real time PCR system in 12 of 240 patients. The 12 influenza A positive cases were with more clusters and chills than the other 228. Certain symptoms and syndromes increased the likelihood of influenza A virus infection. The syndrome of high fever plus chills plus cough, better with clustering of cases in household or workplace, is with the highest likelihood (positive likelihood ratio 95; 95% CI 12-750). Absence of both cluster and chills provides moderate evidence against the infection (negative likelihood ratio 0.51; 95% CI 0.29-0.90).


CONCLUSIONS
Syndromic recognition is not diagnostic but is useful for discriminating between influenza A infection and common cold. In addition to relevant travel history, confirmatory molecular test can be applied to subjects with high likelihood when the disease prevalence is low.
Huang
Po-Yen
PY
Division of Infectious Diseases, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan, Taiwan.
Huang
Ching-Tai
CT
Tsao
Kuo-Chien
KC
Ye
Jung-Jr
JJ
Shie
Shian-Sen
SS
Yang
Ming-Yi
MY
Leu
Hsieh-Shong
HS
Chiang
Ping-Cherng
PC
Weng
Yin-Che
YC
D000328:Adult; D019411:Clinical Laboratory Techniques; D003151:Community Health Centers / Q000706:statistics & numerical data*; D003710:Demography; D005260:Female; D006801:Humans; D009980:Influenza A virus / Q000502:physiology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D016013:Likelihood Functions; D008297:Male; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000175:diagnosis; D013624:Taiwan / Q000453:epidemiology