Viral Co-Morbidity as a Factor Effecting Acute Respiratory Distress Syndrome in H1N1 Influenza Cases Requiring Intensive Care Treatment

Abstract

The 2009 H1N1 pandemic caused severe disease around the world. H1N1 caused disease in younger, healthier people than typically observed for seasonal influenza. Another difference between H1N1 and the seasonal variant is that H1N1-infected patients presented with high rates of diarrhea. It is currently unclear whether the diarrhea is caused by the H1N1 virus directly, or by some secondary pathogen. Co-infection between H1N1 and a second pathogen could lead to a more severe clinical course due to a synergistic pathologic effect, leading to worse outcomes. Screening of fecal and respiratory samples of ICU patients with laboratory-confirmed H1N1 showed that 9 patients out of 15 (60%) had a positive result for adenovirus. ICU patients were divided into an H1N1 alone group or an H1N1/adenovirus co-infection group, and after a retrospective chart review, these groups were compared with respect to a number of characteristics. In addition, 2 pairs of matched acute and convalescent sera were examined by immunoelectron microscopy for seroconversion with respect to adenovirus, and both samples showed a significant increase in titre. The two groups were compared in terms of demographics, complaints of diarrhea, nausea, and vomiting on initial presentation, course in hospital, time course of illness, co-morbidities, complications, and mortality. There were no significant differences between the groups. However, given the limited availability of fecal, respiratory, and blood samples for adenovirus testing, we suspect that a number of adenovirus cases were missed. Identification of these cases could potentially alter the results of our analysis. In conclusion, patients with H1N1 alone and H1N1/adenovirus co-infection are similar in demographics, clinical course, and outcomes.