Rhinoviruses as an underestimated cause of influenza-like illness in pregnancy during the 2009-2010 influenza pandemic.

During the 2009-2010 influenza pandemic, pregnant women were identified at high risk for severe infection. In case of influenza-like illness they were systematically treated with oseltamivir. When performed, virological diagnosis showed that some of these women were not influenza-infected. The objectives of the study were to identify viruses which could induce an influenza-like illness in pregnant women during the 2009-2010 pandemic, then to establish possible links between detected viruses and symptoms, and then characterize human rhinoviruses (HRV) strains detected in some samples. Nasal swabs from 78 pregnant women presenting with influenza-like illness and previously tested for influenza virus by RT-PCR in 2009-2010 were further assayed by multiplex RespiFinder assay and bocavirus PCR to search for 13 other viruses. Genotyping of HRV strains was carried out using partial genomic sequencing in the VP4/VP2 region. Influenza A virus infection was confirmed in 33 women (42%). Non-influenza viruses were detected in 18 additional cases (23%). Rhinoviruses were the most numerous (13%) and belonged to 9 different genotypes distributed between the 3 genogroups. When comparing symptoms observed in influenza-infected women and women infected by other viruses, shivers were more frequent in the former group (P=0.02), and expectorations in the latter (P=0.03). During the influenza pandemic 2009-2010, non-influenza viruses and mostly rhinoviruses were an underestimated cause of influenza-like illness in pregnant women. Viral diagnosis should help to stop empiric oseltamivir therapy in influenza-negative patients and antibiotic treatment in patients infected with a non-influenza virus.