Severe pandemic (H1N1) 2009 influenza with false negative direct fluorescent antibody assay: Case series

doi:10.1016/j.jcv.2009.07.023

Journal of Clinical Virology

Volume 46, Issue 3, November 2009, Pages 279-281

https://doi.org/10.1016/j.jcv.2009.07.023 Get rights and content

Abstract

Between May and June of 2009 we observed 4 patients that presented with severe influenza-like symptoms and respiratory failure. All cases tested negative for influenza A and B by direct fluorescent antibody assay. Further investigation revealed all cases to be positive for pandemic (H1N1) 2009 influenza virus by real-time RT-PCR. This article includes a description of these cases and the characteristics associated with them.

Section snippets

Why this case series is important

On June 11th, 2009 the World Health Organization raised the alert level of novel (H1N1) influenza A virus (now re-named pandemic (H1N1) 2009 influenza virus) to phase 6, declaring the first pandemic of the 21st century.¹ To date, 94,512 cases have been confirmed worldwide with 429 fatalities.² In the United States alone, 37,246 cases have been diagnosed, 211 of which have resulted in death.³ This number may very well merely represent the tip of the iceberg as the great majority of patients with

Case 1

A 28-year-old male with history of mild intermittent asthma presented to the emergency room complaining of a 3-day history of high fevers, chills, dry cough and 1-day history of shortness of breath and rash. He worked in an office with co-workers who had upper respiratory symptoms. On presentation he was febrile to 39.2 °C, his blood presure was 101/60 mmHg, heart rate 115 beats/min, respiratory rate 29 breaths/min and oxygen saturation 68% on room air. He was noted to be in severe respiratory

Other similar and contrasting cases in the literature

Our case series might represent a phenomenon being observed in other affected regions. In Michigan, 10 patients that required intensive care unit admission, tested positive for pandemic (H1N1) 2009 influenza by RT-PCR despite a negative influenza DFA. In contrast with our patients, none of the cases had evidence of secondary bacterial pneumonia either by blood culture or broncho-alveolar lavage.⁵

Discussion

In the wake of the influenza pandemic, reliable testing is of the essence. A recent article published in this journal by Ginocchio et al. demonstrated the low sensitivity of rapid-antigen testing and viral DFA for pandemic (H1N1) 2009 influenza.⁶ Unfortunately, these are presently the most commonly used testing modalities to detect influenza. Our case series illustrates that a negative DFA result should not discourage treating physicians from pursuing molecular testing, particularly for severe

Funding

None.

Competing interests

None declared.

Ethical approval

This study was approved by the Mount Sinai School of Medicine Program for the Protection of Human Subjects

References (9)

C.C. Ginocchio et al.
Evaluation of multiple test methods for the detection of the novel 2009 influenza A (H1N1) during the New York City outbreak
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World Health Organization. Statement to the press by WHO Director-General Dr. Margaret Chan....
World Health Organization. Pandemic (H1N1) 2009—Update 58....
Centers for Disease Control and Prevention. Novel H1N1 Flu Situation Update....

There are more references available in the full text version of this article.

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Case reportSevere pandemic (H1N1) 2009 influenza with false negative direct fluorescent antibody assay: Case series