Prolonged Shedding of 2009 H1N1 Influenza Virus

A recent study published in the journal, Eurosurveillance, discusses two case reports from France, in which two patients exhibited prolonged shedding of the virus 14 and 28 days after the onset of symptoms. The patients did not have immunodepression and were treated with neuraminidase inhibitors. This prolonged shedding was not associated with the emergence of the resistance mutation H275Y in that has been recorded in some cases.

Viral shedding of seasonal influenza A viruses was initially estimated to occur over a period between five and seven days. In humans experimentally infected with the 2009 H1N1 influenza virus, oseltamivir administration shortened the median duration of viral shedding from 107 to 58 hours. Prolonged shedding of seasonal influenza viruses has been demonstrated in immunocompromised patients even when treated with antiviral drugs, potentially leading to the emergence of viral resistant mutations. Similarly, most patients with pandemic H1N1 influenza infection may be shedding virus from one day before the onset of symptoms until five to seven days after the onset of symptoms. For infections with the pandemic influenza A(H1N1)v virus, prolonged viral shedding has been reported in immunocompromised patients treated with oseltamivir, in association with emergence of viral resistance to the drug.

This could have implications in regards to the spread of the disease. There is not yet a clear pattern on which groups of individuals may shed longer than others, and further studies are need to investigate this.

Source: Eurosurveillance http://eurosurveillance.org/ViewArticle.aspx?ArticleId=19434