Democratic Underground Latest Greatest Lobby Journals Search Options Help Login

Implications of the Emergence of a Novel H1 Influenza Virus (New Eng Jour Med)

Printer-friendly format Printer-friendly format
Printer-friendly format Email this thread to a friend
Printer-friendly format Bookmark this thread
This topic is archived.
Home » Discuss » Editorials & Other Articles Donate to DU
pinto Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Jun-17-09 06:54 PM
Original message
Implications of the Emergence of a Novel H1 Influenza Virus (New Eng Jour Med)
bold highlights are mine ~ pinto

Implications of the Emergence of a Novel H1 Influenza Virus
Robert B. Belshe, M.D.

In this issue of the Journal, there are two reports of recent transmissions of swine influenza viruses in humans. One group of viruses, described by Shinde et al.,1 are triple reassortants of viruses from pigs, humans, and birds, called triple-reassortant swine influenza A (H1) viruses, which have circulated in pigs for more than a decade. The other group, described by the Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team,2 is a recent reassortant of the triple-reassortant swine influenza A (H1) viruses and a Eurasian swine influenza virus, resulting in the swine-origin influenza A (H1N1) virus (S-OIV), currently being transmitted among humans.

The two groups of viruses behave very differently. Triple-reassortant swine influenza A (H1) viruses are found in pigs and may occasionally be transmitted to humans but have not spread efficiently from human to human. S-OIV, in contrast, is not currently known to be epidemic in pigs (although pigs may be infected by exposure to humans), but it is exhibiting human-to-human transmission and has spread to several countries. Both viruses are H1 hemagglutinin viruses, which appeared in humans and swine in 1918 and have subsequently evolved, in both species, into divergent H1 viruses. The current situation is not "1918 again," it is "1918 continued," in that we are still being infected with remnants of the 1918 pandemic influenza virus.

Most adults have substantial immunity to H1 variants that have circulated among humans from 1918 through 1957 and then again from 1977 through the present. Whether cross-reacting antibodies from previous H1 infections will provide protection against S-OIV is not known, but the epidemiologic features of the current S-OIV infections suggest that there may be partial protection from multiple previous influenza infections. The age range of the 642 patients with confirmed cases of S-OIV infection was 3 months to 81 years, but 60% were 18 years of age or younger. This age distribution is typical for seasonal influenza; schoolchildren are the group with the highest rates of influenza, and they spread the virus to household contacts.3 The clinical manifestations of S-OIV also were typical of seasonal influenza, with fever in 94% of patients, cough in 92%, and sore throat in 66%; in addition, however, vomiting (found in 25%) or diarrhea (found in 25%) was common. A total of 36 patients were hospitalized; of the 22 hospitalized patients for whom data were available, several had risk factors: young age (4 patients) or chronic medical conditions (9 patients) or both, or pregnancy (1 patient). The two deaths occurred in a 22-month-old child with chronic medical conditions and a 33-year-old woman who was pregnant. Several hospitalized patients had evidence of pneumonia on radiography, and some had secondary complications. The spectrum of illnesses seems very much like those of seasonal influenza.

The New England Journal of Medicine is owned, published, and copyrighted 2009 Massachusetts Medical Society. All rights reserved.

Printer Friendly | Permalink |  | Top

Home » Discuss » Editorials & Other Articles Donate to DU

Powered by DCForum+ Version 1.1 Copyright 1997-2002
Software has been extensively modified by the DU administrators

Important Notices: By participating on this discussion board, visitors agree to abide by the rules outlined on our Rules page. Messages posted on the Democratic Underground Discussion Forums are the opinions of the individuals who post them, and do not necessarily represent the opinions of Democratic Underground, LLC.

Home  |  Discussion Forums  |  Journals |  Store  |  Donate

About DU  |  Contact Us  |  Privacy Policy

Got a message for Democratic Underground? Click here to send us a message.

© 2001 - 2011 Democratic Underground, LLC