Fast track — ArticlesH1N1 2009 influenza virus infection during pregnancy in the USA
Introduction
Pandemic H1N1 2009 influenza virus infection has been identified as the cause of a widespread outbreak of febrile respiratory infection in the USA1 and worldwide.2 Although the severity of this illness has ranged from mild to severe, little has been reported about how this outbreak has affected pregnant women.3, 4 During both seasonal influenza epidemics5, 6 and previous pandemics,7, 8, 9 pregnant women have increased morbidity and mortality from influenza infection compared with women who are not pregnant. In the present outbreak beginning April, 2009, the second documented death from pandemic H1N1 virus infection in the USA was in a healthy pregnant woman.3 Because of concerns about the severity of disease during pregnancy, the US Centers for Disease Control and Prevention (CDC) implemented enhanced surveillance for pandemic H1N1 influenza virus infections in pregnant women in the USA. This report summarises the cases of infection with pandemic H1N1 influenza virus in pregnant women that have been reported to the CDC during the first month of the outbreak (April 15–May 18, 2009) and deaths associated with this virus during the first 2 months of the outbreak (April 15–June 16, 2009).
Section snippets
Setting
On April 15 and 17, 2009, CDC identified a novel influenza A virus of swine origin in two children in two different counties in California. The children did not have any epidemiological links to each other, and neither had recent exposure to pigs. In response, CDC implemented enhanced surveillance for novel influenza A virus infection.
Pandemic H1N1 is diagnosed from respiratory specimens with a real-time reverse-transcriptase PCR testing assay that was developed at the CDC.1 Initially, CDC
Results
From April 15 to May 18, 2009, CDC received reports of 31 pregnant women with confirmed pandemic H1N1 virus infection and of three pregnant women meeting the definition as a probable case. The women were reported from 13 states: Arizona (n=4), California (13), Colorado (3), Delaware (2), Georgia (1), Iowa (1), Kentucky (1), Massachusetts (1), Michigan (3), Oklahoma (1), Pennsylvania (1), Texas (2), and Washington state (1). They ranged in age from 15–42 years (median 26). Nearly half of the
Discussion
This study summarises the cases of pregnant women with pandemic H1N1 virus infection in the USA and shows that this virus can cause serious illness in healthy pregnant women. Before the present outbreak, published work of influenza virus of swine origin in pregnant women was limited to a single case in 1988: a 32-year-old previously healthy pregnant woman at 36 weeks' gestation was infected with a swine influenza virus, contracted through exposure to pigs, and later died of complications
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