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The importance of influenza diagnosis
Travel Medicine and Infectious Disease (2015) 13, 353e354
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevierhealth.com/journals/tmid
EDITORIAL
The importance of influenza diagnosis Influenza is one of the major infectious diseases in many aspects; global occurrence, pandemic potential and a broad interface between humans and animals i.e. the One Health perspective. The short incubation period and the non-specific symptoms make it a differential diagnosis to a number other infectious diseases. Considered often as a benign disease compared to malaria, septicemia and typhoid fever it tends to be an “all-others-ruled-out-diagnosis” sometimes of less interest to the busy clinician. Still we know that influenza is responsible for abundant hospitalizations and deaths every year [1]. Vaccination within six months of exposition and with a vaccine corresponding to the strain that infects the patient prevents severe disease and death. Correct and swift diagnosis is crucial in preventing further spread at institutions where older or immunocompromised individuals are cared for, but also to avoid unnecessary use of antibiotics and to be able to prescribe antivirals when truly indicated. Travelers returning from tropical areas, where influenza viruses are circulating all year around, and from temperate areas with ongoing seasonal influenza, are spreading the disease effectively further around the globe [2]. It is also well known that influenza must be considered as a differential diagnosis in returning febrile travelers during all seasons and despite lack of respiratory symptoms [3,4]. In this issue of Travel Medicine and Infectious Diseases, Berthod et al. have published a study with the aim to investigate whether physicians are able to identify febrile travelers with influenza on the basis of clinical assessment and to evaluate the usefulness of influenza rapid antigen test (iRDT) for management of the patients [5]. There are limitations of this study, of which one is that the inclusion criteria is not valid for travel related influenza. In the study, illness should occur within 14 days of returning from abroad but given the incubation time of influenza, 1e4 days, the above criteria includes therefore also non-travel related influenza cases. Since the aim of the study is to evaluate clinical assessment of influenza and iRDT the results can, however, be valid for both travel and non-travel related influenza cases. Also, as stated by the authors, the study is not designed to estimated influenza incidence in travelers but reflects instead a daily clinical situation in a busy practice where travel
http://dx.doi.org/10.1016/j.tmaid.2015.09.004 1477-8939/ª 2015 Elsevier Ltd. All rights reserved.
related diagnosis have to be considered at the same time as non-travel related. The sample size of 100 patients of different ages, duration of symptoms, comorbidities and sex is not enough to provide firm conclusions. Also the recruitment period of four years and different viral strains, including the pandemic of 2009/10, as well as different clinicians assessing the patients contributes to the heterogenicity of the study-material. But, taken the limitations into account, the findings add to the discussion of if, when, and how to use iRDT. In the study the iRDT used had a sensitivity of 20% in that particular setting and was therefore not recommended as diagnostic tools by the authors. Other studies have shown that the sensitivity of iRDT was variable but rather low (20e70%) and depending on the setting, prevalence in the population, viral load and age of the patients [6]. A rapid diagnostic PCR-based tool for with higher sensitivity would be highly valuable for both clinicians and patients in order to prevent unnecessary antibiotics and to give antivirals when indicated. Furthermore, by confirming the diagnosis when hospitalization is needed it is easier to prevent nosocomial spreading by isolating the patient from others.
References [1] Thompson WW, Weintraub E, Dhankhar P, Cheng PY, Brammer L, Meltzer MI, et al. Estimates of US influenzaassociated deaths made using four different methods. Influenza Other Respir Viruses 2009;3:37e49. [2] Bedford T, Riley S, Barr IG, Broor S, Chadha M, Cox NJ, et al. Global circulation patterns of seasonal influenza viruses vary with antigenic drift. Nature 2015 Jul 9;523(7559):217e20. [3] Askling HH, Lesko B, Vene S, Berndtson A, Bjo ¨rkman P, Bla ¨ckberg J, et al. Serologic analysis of returned travelers with fever, Sweden. Emerg Infect Dis 2009 Nov;15(11):1805e8. [4] Mutsch M, Tavernini M, Marx A, Gregory V, Lin YP, Hay AJ, et al. Influenza virus infection in travelers to tropical and subtropical countries. Clin Infect Dis 2005 May 1;40(9):1282e7. [5] Berthod D, Genton B, Hatz C, Blum J, de Vallie `re S. Ability of physicians to diagnose influenza and usefulness of a rapid influenza antigen test in febrile returning travelers: a randomized controlled trial. Travel Med Infect Dis 2015;13(5): 394e9. http://dx.doi.org/10.1016/j.tmaid.2015.08.001.
354 [6] Chartrand C, Leeflang MM, Minion J, Brewer T, Pai M. Accuracy of rapid influenza diagnostic tests: a meta-analysis. Ann Intern Med 2012 Apr 3;156(7):500e11.
H.H. Askling* Department of Communicable Diseases Control and Prevention (Smittskydd Stockholm), Box 1753, SE 11891 Stockholm, Sweden
Editorial Department of Medicine, Unit for Infectious Diseases, Solna, Karolinska Institutet, 17176 Stockholm, Sweden *Department of Communicable Diseases Control and Prevention (Smittskydd Stockholm), Box 1753, SE 11891 Stockholm, Sweden. E-mail address: [email protected] 14 September 2015
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevierhealth.com/journals/tmid
EDITORIAL
The importance of influenza diagnosis Influenza is one of the major infectious diseases in many aspects; global occurrence, pandemic potential and a broad interface between humans and animals i.e. the One Health perspective. The short incubation period and the non-specific symptoms make it a differential diagnosis to a number other infectious diseases. Considered often as a benign disease compared to malaria, septicemia and typhoid fever it tends to be an “all-others-ruled-out-diagnosis” sometimes of less interest to the busy clinician. Still we know that influenza is responsible for abundant hospitalizations and deaths every year [1]. Vaccination within six months of exposition and with a vaccine corresponding to the strain that infects the patient prevents severe disease and death. Correct and swift diagnosis is crucial in preventing further spread at institutions where older or immunocompromised individuals are cared for, but also to avoid unnecessary use of antibiotics and to be able to prescribe antivirals when truly indicated. Travelers returning from tropical areas, where influenza viruses are circulating all year around, and from temperate areas with ongoing seasonal influenza, are spreading the disease effectively further around the globe [2]. It is also well known that influenza must be considered as a differential diagnosis in returning febrile travelers during all seasons and despite lack of respiratory symptoms [3,4]. In this issue of Travel Medicine and Infectious Diseases, Berthod et al. have published a study with the aim to investigate whether physicians are able to identify febrile travelers with influenza on the basis of clinical assessment and to evaluate the usefulness of influenza rapid antigen test (iRDT) for management of the patients [5]. There are limitations of this study, of which one is that the inclusion criteria is not valid for travel related influenza. In the study, illness should occur within 14 days of returning from abroad but given the incubation time of influenza, 1e4 days, the above criteria includes therefore also non-travel related influenza cases. Since the aim of the study is to evaluate clinical assessment of influenza and iRDT the results can, however, be valid for both travel and non-travel related influenza cases. Also, as stated by the authors, the study is not designed to estimated influenza incidence in travelers but reflects instead a daily clinical situation in a busy practice where travel
http://dx.doi.org/10.1016/j.tmaid.2015.09.004 1477-8939/ª 2015 Elsevier Ltd. All rights reserved.
related diagnosis have to be considered at the same time as non-travel related. The sample size of 100 patients of different ages, duration of symptoms, comorbidities and sex is not enough to provide firm conclusions. Also the recruitment period of four years and different viral strains, including the pandemic of 2009/10, as well as different clinicians assessing the patients contributes to the heterogenicity of the study-material. But, taken the limitations into account, the findings add to the discussion of if, when, and how to use iRDT. In the study the iRDT used had a sensitivity of 20% in that particular setting and was therefore not recommended as diagnostic tools by the authors. Other studies have shown that the sensitivity of iRDT was variable but rather low (20e70%) and depending on the setting, prevalence in the population, viral load and age of the patients [6]. A rapid diagnostic PCR-based tool for with higher sensitivity would be highly valuable for both clinicians and patients in order to prevent unnecessary antibiotics and to give antivirals when indicated. Furthermore, by confirming the diagnosis when hospitalization is needed it is easier to prevent nosocomial spreading by isolating the patient from others.
References [1] Thompson WW, Weintraub E, Dhankhar P, Cheng PY, Brammer L, Meltzer MI, et al. Estimates of US influenzaassociated deaths made using four different methods. Influenza Other Respir Viruses 2009;3:37e49. [2] Bedford T, Riley S, Barr IG, Broor S, Chadha M, Cox NJ, et al. Global circulation patterns of seasonal influenza viruses vary with antigenic drift. Nature 2015 Jul 9;523(7559):217e20. [3] Askling HH, Lesko B, Vene S, Berndtson A, Bjo ¨rkman P, Bla ¨ckberg J, et al. Serologic analysis of returned travelers with fever, Sweden. Emerg Infect Dis 2009 Nov;15(11):1805e8. [4] Mutsch M, Tavernini M, Marx A, Gregory V, Lin YP, Hay AJ, et al. Influenza virus infection in travelers to tropical and subtropical countries. Clin Infect Dis 2005 May 1;40(9):1282e7. [5] Berthod D, Genton B, Hatz C, Blum J, de Vallie `re S. Ability of physicians to diagnose influenza and usefulness of a rapid influenza antigen test in febrile returning travelers: a randomized controlled trial. Travel Med Infect Dis 2015;13(5): 394e9. http://dx.doi.org/10.1016/j.tmaid.2015.08.001.
354 [6] Chartrand C, Leeflang MM, Minion J, Brewer T, Pai M. Accuracy of rapid influenza diagnostic tests: a meta-analysis. Ann Intern Med 2012 Apr 3;156(7):500e11.
H.H. Askling* Department of Communicable Diseases Control and Prevention (Smittskydd Stockholm), Box 1753, SE 11891 Stockholm, Sweden
Editorial Department of Medicine, Unit for Infectious Diseases, Solna, Karolinska Institutet, 17176 Stockholm, Sweden *Department of Communicable Diseases Control and Prevention (Smittskydd Stockholm), Box 1753, SE 11891 Stockholm, Sweden. E-mail address: [email protected] 14 September 2015