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Rapid Molecular Detection and Differentiation of Influenza Viruses A and B
Published on: January 30, 2017
Influenza-like illness criteria were poorly related to laboratory-confirmed influenza in a sentinel surveillance
José María Navarro-Marí1, Mercedes Pérez-Ruiz, Purificación Cantudo-Muñoz
1Servicio de Microbiología, Hospital Universitario Virgen de las Nieves, Granada, Spain. josem.navarro.sspa@juntadeandalucia.es
Objective:
To analyze the most related clinical data for influenza and the utility of influenza-like illness criteria as the clinical threshold for sampling in an influenza sentinel surveillance over a 3-year period.
Methods:
Sentinel physicians collected throat specimens and data from outpatients with acute respiratory infection (< or = 72 hours duration). Laboratory-confirmed influenza infection was compared with independent symptoms and the influenza-like illness criteria, as defined by the Classification Committee of the World Organization of Family Doctors.
Results:
From 1934 patients, 359 (18.56%) yielded positive results for influenza viruses. Only 199 (55.4%) of laboratory-confirmed cases fulfilled clinical criteria of influenza-like illness: positive and negative predictive value (PPV and NPV) of 0.36 and 0.88, respectively. Fever, cough, and rhinorrhea individually correlated with influenza infections (PPV: 0.30, 0.20, and 0.20, respectively; NPV: 0.92, 0.87, and 0.85, respectively). Multivariate analysis demonstrated that the correlation of influenza infection with the presence of fever and cough was similar to the correlation between influenza infection and influenza-like illness criteria (odds ratio 2.24 vs. 2.71, respectively).
Conclusion:
Influenza-like illness criteria are poorly related to laboratory-confirmed influenza. For early detection of influenza viruses in surveillance systems, a less restrictive clinical criterion (specifically, acute respiratory infection) perhaps should be followed.
Insights
Influenza-like illness criteria are not reliable for detecting influenza. A broader definition of acute respiratory infection may improve surveillance for early influenza virus detection.
Area of Science:
- Epidemiology
- Infectious Diseases
- Public Health Surveillance
Background:
- Influenza surveillance relies on accurate clinical case definitions.
- Influenza-like illness (ILI) criteria are commonly used but their utility requires evaluation.
Purpose of the Study:
- To analyze clinical data related to influenza.
- To assess the effectiveness of influenza-like illness criteria in sentinel surveillance.
Main Methods:
- Outpatients with acute respiratory infection provided throat specimens and data.
- Laboratory-confirmed influenza cases were compared against symptoms and ILI criteria.
Main Results:
- 18.56% of patients tested positive for influenza.
- Only 55.4% of confirmed influenza cases met ILI criteria (PPV 0.36, NPV 0.88).
- Fever and cough showed moderate correlation with influenza, similar to ILI criteria.
Conclusions:
- Influenza-like illness criteria show poor correlation with laboratory-confirmed influenza.
- A less restrictive criterion, such as acute respiratory infection, may enhance early influenza detection in surveillance.
