2009 Pandemic Influenza A/H1N1 Viral Infection: Clinical and Pulmonary Pathological Findings in 34 Fatalities
CG Deshpande, JR Gill, ZM Sheng, SF Ely, DG Guinee, MB Beasly, J Suh, DJ Mollura, DM Morens, M Bray, JK Taubenberger, WD Travis. Univ of Pennsylvania, Philadelphia, PA; New York Univ School of Medicine, New York, NY; NIAID/NIH, Bethesda, MD; Virginia Mason Med Ctr, Seattle, WA; Mount Sinai Med Ctr, New York, NY; Stony Brook Univ Med Ctr, Stony Brook, NY; MSKCC, New York, NY
Background: In June 2009, World Health Organization (WHO) declared an influenza pandemic due to a novel swine-origin influenza A/H1N1 virus. By September 25, 2009, WHO reported 43,771 confirmed infections with 593 deaths in United States. We describe 34 deaths with confirmed influenza A/H1N1 virus infection investigated by New York City Office of Chief Medical Examiner and consultation service of a co-author.
Design: Autopsies were performed on all decedents. Clinical information was obtained from medical records and/or medicolegal investigation. Nasopharyngeal and tracheal swabs were analyzed for H1N1 viral RNA by real-time reverse-transcriptase polymerase chain reaction (rRT-PCR). Histopathologic and microbiologic evaluation was performed using H&E, B&H tissue Gram and GMS stains. Formalin fixed, paraffin embedded (FFPE) autopsy tissue sections were analyzed for influenza A virus matrix gene and H1N1 hemagglutinin gene by rRT-PCR. H1N1 viral antigen tissue localization was detected by immunohistochemistry (IHC).
Results: Majority (62%) of these decedents were 25-49 years of age. Tracheitis, bronchiolitis and diffuse alveolar damage (74%) were noted in most. Influenza viral antigen was observed by IHC, most commonly in the epithelium of tracheobronchial tree, but in some, also in alveolar epithelial cells, submucosal glands and macrophages. Histologic and microbiologic evidence of bacterial pneumonia was detected in 55% (most commonly streptococcus pneumoniae). Frequent symptoms were fever>38°C (94%), cough (91%) or dyspnea (73%). Comorbidities included obesity (72%), cardiorespiratory diseases, immunosuppressed states and diabetes mellitus with 91% having one or more.
Conclusions: Pulmonary pathological findings in fatal disease caused by the novel pandemic influenza virus are similar to those identified in past pandemics. Bacterial co-infections of the respiratory tract are common. Pre-existing obesity, cardiorespiratory disease and other comorbidites were present in majority.
Tuesday, March 23, 2010 2:30 PM
Platform Session: Section F, Tuesday Afternoon