Editor's note #4

VDU's Editor asked to comment on recent WHO statement about H7N9 severity on BBC World News' Newsday show with Rico Hizon. 

Video currently viewable at the Australian Infectious Diseases Research Centre at The University of Queensland.

New summary of H7N9 events.

The US CDC publish a wrap-up in an early release issue of Morbidity and Mortality Weekly Report.

Study supports poor H7N9 transmission - from anything!

A new paper in by J. Han et al. Emerging Microbes and Infection concludes that neither 2 vendors in an H7N9-positive poultry market visited by the H7N9-positive patient (our Case#10, also studied in recent Lancet article) nor his close contacts, were WHO RT-rtPCR positive. 

So picking up H7N9 is certainly not a frequent thing. Also supported by the few cases that have been identified considering the population in these areas that move through and interact with birds and the markets. 

Also, once you have it, transmitting H7N9 it seems to be an infrequent event.

Swapping H1N1's PA and NS into H5N1 flu helps H5N1 spread.

A new study by Hualan Chen's group at Harbin Veterinary Research Institute published in Science reveals that avian influenza A(H5N1) can acquire mammalian transmissibility if it acquires the right segments of human influenza A(H1N1). This was not a mutation study, but a whole gene segment-swapping study (creatingreassortants). 

This work was conducted in mice (for lethality studies) and guinea pigs (for transmission) and yielded different results compared to similar studies using ferret models, which did spread via aerosols or droplets.

Some have expressed their dismay at the study itself. It seemed to fly in the face of the many concerned scientists who wrote at length after similar studies, classified as 'gain of function' virus research, were described using mutations in flu genes, instead of entire gene segments. "Play" was pressed on the voluntary pause in highly pathogenic avian influenzavirus H5N1 research in Feb 2013 after a list of uber-expert flu researchers declared that sufficient time had passed, explanations, debates, reviews and revisions had occurred. 

Those scientists suitably supported and qualified to do so should get back to the bench in order to better prepare humanity for pandemic influenzas of the future. Timely. There were 3 Chinese affiliations as signatories on this article including Harbin Veterinary Research Institute's Prof Hualan Chen.

Whatever you think of this study, the outcome is a very sobering reminder of what chance could be capable of in those locations where animal and human flu viruses co-circulate. 

Fit and better-transmitting viruses can result.

How reliable are the H7N9 real-time RT-PCRs for low viral loads?

An interesting document that compares the effectiveness of some different diagnostic PCR methods for use in H7 or N9-based flu diagnosis. It seems to show that in a couple of instances H7-specific or H9-specific molecular methods will fail (1:10,000,000 is a pretty extreme dilution) to detect H7N9 at low levels while some assay fail to amplify the intended target altogether. 

This sort of assay variation is pretty commonplace when you compare different PCR designs for the same target. It's a major reason why everyone prefers to design their own assay; each are convinced there's is the best. From this document, the people behind the OFFLU (FLI-H7) assay happen to be right. 

How these data relate to viral load in the human (and animal) samples these may be/have been used on is unknown. This sort of variance may contribute to negative throat swabs in H7N9-cases subsequently proven positive using lower respiratory tract samples (e.g. sputum) in which the viral load is presumed to be higher.

OFFLU: a network of expertise on animal influenza established jointly in 2005 by the World Organisation for Animal Health (OIE) and the Food and Agriculture Organization of the United Nations (FAO) to support and coordinate global efforts to prevent, detect and control important influenzas in animals.
CNIC: Chinese National Influenza Center

That (don't call me novel) coronavirus is back!

Media reports, FluTrackers and Avian Flu Diary describe five recent deaths and two other critically ill cases under close watch in the Al-Ahasa region of the Kingdom of Saudi Arabia, linked to infection with the newly identified human coronavirus HCoV-EMC. This virus was first isolated in September 2012 from a 60M (60-year-old male) with pneumonia and renal failure in Jeddah, KSA. 

Further evidence for bats as a major source of CoVs came in a recent study in Emerging Infectious Diseases. Yang and colleagues identified a novel CoV from each of 2 bat species. 

The newly identified betacoronaviruses (betaCoVs), Bat Rp-coronavirus/Shaanxi2011 and Bat Cp-coronavirus/Yunnan2011 (rolls of the tongue doesn't it?) were not that closely related to human betaCoVs but resided in the bat verison of the SARS-like COVs.

First weekly H7N9 report from China?

A report from the Ministry of Health describes 19 cases during the period spanning from April 25th to May 1st. 

There are also 2 new deaths (total now at 26)- but no details provided for any of the cases. Stay tuned next Thursday for more.

Four reassortment events led to H7N9 emergence.

With thanks to Prof. Ross Barnard, University of Queensland for helpful contributions.

A new article just published at the Lancet describes a detailed genetic analysis of four H7N9 virus sequences, in the context of all likely contributing influenza virus sequence. The resultant virus' HA and NA genes may have been contributed by migratory birds a year prior to acquisition of internal genes from poultry influenza viruses. 

Since its emergence "several months ago", H7N9 has divided into at least two different groups (lineages). One strain (Shanghai/1) has signs of oseltamivir resistance.

Influenza virus transmission.

An interesting blog post from 2006 by Revere on some aspects of what H5N1 virulence (in terms of disease severity), transmission and preconceptions. 

Do we put too much stock in believing that recently emerged viruses eventually settle in to their new hosts, seeking a perfect balance between virus replication, transmission and host mortality? 

In other words, do viruses adapt over time so that originally severe infection outcomes (like pneumonia) become mild illnesses (like the common cold or just feeling a it crook). 

There may be some parallels to be drawn with H7N9 as we continue down its path. 

Or perhaps H7N9 has been adapting to humans for longer than we think?

A(nother) new real-time PCR-based H7N9 test.

US CDC have made available their CDC H7N9 rRT-PCR for use on suspect cases (see interim guidance for defining cases) and in combination with their existing Flu rRT-PCR Dx Panel ("r"=real-time; "Dx"=Diagnosis/Diagnostic) after FDA support through an Emergency Use Authorization.