pablomorgan
Well-known member
In January 2006, the US Centers for Disease Control and Prevention (CDC) recommended against the use of adamantanes due to a significant increase in resistance among circulating influenza A(H3N2) viruses.1 As a result, neuraminidase inhibitors (NAIs) became the only class of antiviral agents recommended for the treatment and prophylaxis of influenza virus infections in the United States.1-2 Since their introduction in 1999, the proportion of influenza viruses resistant to NAIs among circulating influenza viruses has been low, generally less than 1% of isolates tested worldwide.3-5
However, during the 2007-2008 influenza season, increased levels of resistance to oseltamivir, 1 of the 2 licensed NAIs, were detected for the first time in the United States and worldwide.4, 6-7 In addition, early 2008-2009 influenza season surveillance data suggest that oseltamivir resistance among influenza A(H1N1) viruses will most likely be higher during the upcoming season.8 Resistance to oseltamivir was identified in only 1 influenza A virus subtype, influenza A(H1N1), and all of the identified resistant viruses have had the same mutation known to confer resistance, H274Y (N2 NA numbering) in the viral neuraminidase.6 Before the 2007-2008 influenza season, detection of oseltamivir-resistant viruses in humans had typically been reported only among persons treated with oseltamivir,9-13 and human-to-human transmission of an NAI-resistant virus had never been documented.14-15 In addition, clinical case reports and in vitro and animal studies suggested that the infectivity and replicative ability of NAI-resistant viruses were compromised.16-18 As a result, it was unknown whether resistant viruses would cause clinical illness similar to other influenza viruses.
In this study, we described patients infected with oseltamivir-resistant influenza A(H1N1) identified from influenza surveillance in the United States during the 2007-2008 influenza season and described risk factors for infection with oseltamivir-resistant viruses. In addition, we compared characteristics of patients with oseltamivir-resistant and oseltamivir-susceptible influenza A(H1N1) infection to determine whether there were any differences in demographic or epidemiological characteristics, clinical symptoms, severity of illness, or clinical outcomes.
http://jama.ama-assn.org/cgi/content/full/2009.294
However, during the 2007-2008 influenza season, increased levels of resistance to oseltamivir, 1 of the 2 licensed NAIs, were detected for the first time in the United States and worldwide.4, 6-7 In addition, early 2008-2009 influenza season surveillance data suggest that oseltamivir resistance among influenza A(H1N1) viruses will most likely be higher during the upcoming season.8 Resistance to oseltamivir was identified in only 1 influenza A virus subtype, influenza A(H1N1), and all of the identified resistant viruses have had the same mutation known to confer resistance, H274Y (N2 NA numbering) in the viral neuraminidase.6 Before the 2007-2008 influenza season, detection of oseltamivir-resistant viruses in humans had typically been reported only among persons treated with oseltamivir,9-13 and human-to-human transmission of an NAI-resistant virus had never been documented.14-15 In addition, clinical case reports and in vitro and animal studies suggested that the infectivity and replicative ability of NAI-resistant viruses were compromised.16-18 As a result, it was unknown whether resistant viruses would cause clinical illness similar to other influenza viruses.
In this study, we described patients infected with oseltamivir-resistant influenza A(H1N1) identified from influenza surveillance in the United States during the 2007-2008 influenza season and described risk factors for infection with oseltamivir-resistant viruses. In addition, we compared characteristics of patients with oseltamivir-resistant and oseltamivir-susceptible influenza A(H1N1) infection to determine whether there were any differences in demographic or epidemiological characteristics, clinical symptoms, severity of illness, or clinical outcomes.
http://jama.ama-assn.org/cgi/content/full/2009.294