Dual H1N1/H3N2 flu infections in Cambodia in 2009 raise concern

[Shiloh]

Source: http://www.google.com/hostednews/afp...1471df02dc.dd1

Dual flu infections in Cambodia raise concern

(AFP) ? 2 hours ago

WASHINGTON ? A rare case of people being infected with both swine and seasonal flu has been documented in Cambodia, raising concern about the possibility of a potent combination strain, said a study out Wednesday.

The unusual diagnoses were made in a 23-year-old teacher and one of his young male students, who had H1N1 and a human season flu H3N2 at the same time, said the findings in the American Journal of Tropical Medicine and Hygiene.

Neither patient was hospitalized and their illnesses did not appear any more severe than in typical patients who are afflicted with a single strain.

The cases date back to 2009, the year the pandemic H1N1 flu emerged, and do not pose a current threat, but rather remind experts of the dangers that a strain such as H5N1 bird flu could mix with human flu and sicken millions...

[Giuseppe]

Re: Dual H1N1/H3N2 flu infections in Cambodia in 2009 raise concern

Since both A(H1N1)pdm09 and human seasonal A(H3N2) strains are circulating in world population, it is difficult that a new reassortant containing one or two of the surface glycoproteins could represent a health risk of great magnitude because widespread immunity against the two viruses into the population.

There is not a way to predict whether A(H1N1)pdm09 will reassort with A(H5N1) avian influenza virus or another animal origin subtype and additionally whether this putative new reassortant may retain donor virulence or will result in severe or life-threatening illness in humans.

(IOH)

[Giuseppe]

Re: Dual H1N1/H3N2 flu infections in Cambodia in 2009 raise concern

[Source: American Journal of Tropical Medicine and Hygiene, full text: (LINK). Abstract, edited.]

Dual Infection of Novel Influenza Viruses A/H1N1 and A/H3N2 in a Cluster of Cambodian Patients

• Christopher A. Myers, Matthew R. Kasper, Chadwick Y. Yasuda, Chin Savuth, David J. Spiro, Rebecca Halpin, Dennis J. Faix, Robert Coon, Shannon D. Putnam, Thomas F. Wierzba and Patrick J. Blair*

Author Affiliations

Naval Health Research Center, San Diego, California; US Naval Medical Research Unit No. 2, Phnom Penh, Kingdom of Cambodia; National Institute of Public Health, Ministry of Health, Phnom Penh, Kingdom of Cambodia; J. Craig Venter Institute, Rockville, Maryland


Author Notes

• Authors' addresses: Christopher A. Myers, Dennis J. Faix, and Robert Coon, Naval Health Research Center, San Diego, CA, E-mails: Chris.Myers2@med.navy.mil, dennis.faix@med.navy.mil, and robert.coon@med.navy.mil. Matthew R. Kasper, Chadwick Y. Yasuda, Shannon D. Putnam, and Thomas F. Wierzba, US Naval Medical Research Unit No. 2, Phnom Penh, Kingdom of Cambodia, E-mails: Matthew.Kasper@med.navy.mil, Chad@namru2.org.kh, shan.putnam@med.navy.mil, and twierzba@IVI.int. Chin Savuth, National Institute of Public Health, Ministry of Health, Phnom Penh, Kingdom of Cambodia, E-mail: savuth_chin@yahoo.com. David J. Spiro and Rebecca Halpin, J. Craig Venter Institute, Rockville, MD, E-mails: david.spiro@nih.gov and rhalpin@jcvi.org. Patrick J. Blair, Naval Health Research Center, San Diego, CA and US Naval Medical Research Unit No. 2, Phnom Penh, Kingdom of Cambodia, E-mail: patrick.blair@med.navy.mil.

1. ↵*Address correspondence to Patrick J. Blair, Department of Respiratory Diseases, Naval Health Research Center, 140 Sylvester Road, San Diego, CA 92106. E-mail: patrick.blair@med.navy.mil

Abstract.



During the early months of 2009, a novel influenza A/H1N1 virus (pH1N1) emerged in Mexico and quickly spread across the globe. In October 2009, a 23-year-old male residing in central Cambodia was diagnosed with pH1N1. Subsequently, a cluster of four influenza-like illness cases developed involving three children who resided in his home and the children's school teacher. Base composition analysis of internal genes using reverse transcriptase polymerase chain reaction and electrospray ionization mass spectrometry revealed that specimens from two of the secondary victims were coinfected with influenza A/H3N2 and pH1N1. Phylogenetic analysis of the hemagglutinin genes from these isolated viruses showed that they were closely related to existing pH1N1 and A/H3N2 viruses circulating in the region. Genetic recombination was not evident within plaque-purified viral isolates on full genome sequencing. This incident confirms dual influenza virus infections and highlights the risk of zoonotic and seasonal influenza viruses to coinfect and possibly, reassort where they cocirculate.


Disclaimer: The views expressed in this article are of the authors and do not reflect the official policy or position of the Department of the Navy, the Department of Defense, or the US Government.


Footnotes

• Financial support: This work was funded in part by grants from the US Department of Defense Armed Forces Health Surveillance Center division of the Global Emerging Infections Surveillance and Response System (AFHSC/GEIS) and the US Defense Advanced Research Projects Agency, (DARPA) under work unit number 60941. A portion of this project was funded by the National Institute of Allergy and Infectious Diseases, National Institute of Health, Department of Health and Human Services under contract number HHSN272200900007C.

• Received February 16, 2011.
• Accepted June 6, 2011.

• ?The American Society of Tropical Medicine and Hygiene

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[Vibrant62]

Re: Dual H1N1/H3N2 flu infections in Cambodia in 2009 raise concern

Some grounds for concern about such a reassortment were highlighted in this study.

http://www.flutrackers.com/forum/showthread.php?t=166945&highlight=h3n2+h1n1+reassortment

However, I agree that it is less likely that a virulent form would emerge if comprised of virus genes to which there is a high level of underlying human immunity; the greater concern would be if this occurred with a novel swine genes or other non-human variant as part of the mix.

[alert]

Re: Dual H1N1/H3N2 flu infections in Cambodia in 2009 raise concern

I'm not sure why this is big news now. We already have a report of a similar case in Toronto in which a reassortment actually occurred:

http://www.flutrackers.com/forum/showthread.php?p=411660

And we also have several reports from Arabic language sources in Egypt of a possibly large number of such cases (and post #39 of the following thread quotes a CDC official as saying that as many as 5% of all flu infections are actually dual infections):

http://www.flutrackers.com/forum/showthread.php?t=123673

[Laidback Al]

Re: Dual H1N1/H3N2 flu infections in Cambodia in 2009 raise concern

I'm not sure why this is big news now. We already have a report of a similar case in Toronto in which a reassortment actually occurred:

http://www.flutrackers.com/forum/showthread.php?p=411660

And we also have several reports from Arabic language sources in Egypt of a possibly large number of such cases (and post #39 of the following thread quotes a CDC official as saying that as many as 5% of all flu infections are actually dual infections):

http://www.flutrackers.com/forum/sho...d.php?t=123673

I think it is worth reminding everyone that there are a number of different ways a novel influenza virus can reassort (in humans and animals) to produce a pandemic strain.