Oct 31, 2011 (CIDRAP News) – In a study of respiratory tissue samples from patients who died from undiagnosed respiratory illnesses during the 2009 H1N1 pandemic, more than half were negative for the virus, shedding light on a host of other diseases that often had similar clinical signs.

Researchers from the US Centers for Disease Control and Prevention’s (CDC’s) Infectious Diseases Pathology Branch analyzed tissue specimens from 450 patients that they received from Apr 29, 2009, through May 5, 2010. Their findings appear in the November issue of Emerging Infectious Diseases.

To explore other respiratory diseases that patients died from during the pandemic, they focused most of their analysis on the 250 samples (56%) that were negative for the 2009 H1N1 virus after real-time reverse transcription polymerase chain reaction (rRT-PCR) testing. Patients ranged in age from 8 days to 81 years. Of 164 with available medical information, 127 (77%) had one or more underlying medical conditions.

People who died from other respiratory diseases were more likely than H1N1 patients to be young and less likely to be obese or have asthma. Fever, cough, and shortness of breath were also less common.

The group analyzed the negative 2009 H1N1 samples further, including use of special histochemical stains, immunohistochemical tests, and molecular assays. They found at least one etiologic agent in 69 (28%) of the 250 specimens. Bacterial pathogens were found in 44 patients, with Staphylococcus aureus and Streptococcus pneumoniae most common.

Viral agents were found in the specimens of 26 patients, and most were seasonal or unsubtypable influenza A viruses. Others included respiratory syncytial virus and adenovirus. The pathology team found multiple fungal pathogens in samples from two patients. Continued:


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