Avian Flu Diary: CIDRAP: NEJM Articles On The Pathogenesis and Distribution Of H1N1 in Mexico

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Maryn McKenna, writing tonight for CIDRAP (Center For Infectious Disease Research And Policy) News, brings us an overview of two NEJM (New England Journal of Medicine) articles published today on the the H1N1 pandemic virus.

We’ve been waiting for clinical details to emerge, particularly regarding patients with bad outcomes or severe symptoms. What we learn today reinforces information we’ve only gotten in drips and drabs:

That while most people recover without incident, the H1N1 virus can cause serious respiratory illness and multi-organ failure in some patients – even those without previously existing medical conditions.

Here are the opening paragraphs to Maryn’s article. Follow the links to read it in it's entirety.

Novel H1N1 flu can cause severe respiratory illness

Maryn McKenna Contributing Writer

Jun 29, 2009 (CIDRAP News) – Novel H1N1 influenza can cause severe respiratory illness, profound lung damage, and death even in patients with no underlying conditions to make them vulnerable, a team of physicians from Mexico report in a rush article published online today by the New England Journal of Medicine (NEJM).

The analysis of 18 patients hospitalized with H1N1 (swine) flu at the National Institute of Respiratory Diseases (INER) in Mexico during the pandemic's earliest days reveals that fewer than half had underlying medical conditions, but more than half needed mechanical ventilation within a day of admission. Seven of the 18 died.

In a companion article, also published in advance online today, a multi-national team from Mexico and the United States document the age distribution of the first month of the H1N1 pandemic in Mexico, where the disease appears to have struck first, and confirm its unusual pattern of severe pneumonia among younger patients. Matching the pattern to those of earlier pandemics, the team speculates on the "biologic plausibility of partial protection" in older people exposed to mid-20^th century strains of seasonal flu.

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Perez-Padilla R, de la Rosa-Zamboni D, Ponce de Leon S et al. Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico. N Engl J Med 2009 (published online Jun 29) [Full text]

Chowell D, Bertozzi S, Arantxa Colchero M et al. Severe respiratory disease concurrent with the circulation of H1N1 influenza. N Engl J Med 2009 (published online Jun 29) [Full text]

In a separate article, Lisa Schnirring of CIDRAP brings us a look at two more NEJM articles on the evolutionary path that the H1N1 virus has taken since it first appeared in 1918.

Experts look for clues in 1918 pandemic virus family tree

Lisa Schnirring Staff Writer

Jun 29, 2009 (CIDRAP News) – To outside observers, the novel H1N1 virus spreading quickly to every corner of the globe must seem like it came out of nowhere, but the organism is a fourth generation of the 1918 pandemic virus and comes from an H1N1 family tree that is colorful and complex, according to two historical reviews that appear today in the New England Journal of Medicine (NEJM).

Understanding the history of swine influenza viruses, particularly their contribution to the 1918 pandemic virus, underscores the need to better comprehend zoonotic viruses as well as the dynamics of human pandemic viruses that can arise from them, the authors report in an early online NEJM edition.

The world is still in a "pandemic era" that began in 1918, wrote three experts from the National Institute of Allergy and Infectious Diseases (NIAID), senior investigator David Morens, MD, medical epidemiologist Jeffery Taubenberger, MD, PhD, and NIAID director Anthony Fauci, MD.

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