Tuesday, April 16, 2013

H7N9- Follw up post

     The last weeks block buster news on H7N9 is still the most important news. Its everywhere on the web. For Scientific publishers like Nature news and Science news, that's the most important flash news. Even news papers, magazines, everywhere it is up. (Oh, by the way microbiology blogs too!!!). The sudden data build up, and opinions in publication, in the last week around the globe has made me give a thought again. Perhaps, I need to write some follow up.
Fig 1: Schematic diagram of novel
influenza A(H7N9) virus generation.
    For people who haven't yet read my previous post (Link), need to read it up first. As of on 15 April 2013, WHO data (Link), 60 patients have been laboratory-confirmed with influenza A(H7N9) virus in China which includes 13 deaths. Almost all possible contacts are being strictly quarantined. There are no new cases confirmed, with officials reporting a controlled situation. A heavy inspection of 1,127 restaurants, 95 poultry farms, 16 supermarkets and 30 other related companies has been evaluated with not much of a finding. Source.

    A very detailed genetic analysis has been reported by Kageyama etal, and by comparing as many possible from the database. As I mentioned in my previous post, an important mutation is T160A substitution in H3 loop, leading to a loss of glycosylation site, results in increased virus binding to human-type receptors. The second point is all studied genomes shows deletion at positions 69–73 of the NA stalk region. Based on the data, it is most likely that, this new assortent is possibly a mix, as shown by the author in Fig 1.

     So, with that background, I want to revisist  a question that i asked last time. So the main question is, "Is this the pandemic strain?".

     The most important feature that could be attributed to a pandemic strain in influenza is almost unchallengably, the agility to transmit and move around too fast. First case being reported on March and its now more than a 40 days have passed since, with a few confirmed cases. Data is still lacking. If there's a data on seroconversion we would have better projection. If we are to see a large number of people with antibodies, but no apparent infection that means this virus is spreading, but the clinical apparency is low. If we are to find low seroconversion, then arguably, we are talking of a possible pandemic strain. To date, there is no documented evidence of any sustained human-to-human spread of the H7N9 virus. Lipsitch says, "It's too soon to say how big a threat H7N9 poses because we don't know how many animals of which species have it, how genetically diverse it is, or what the geographic extent is, It looks as though it will be at least as challenging as H5N1."

     Whatever the case maybe, it is not as bad as the H1N1 was. And the most important question currently faced is what is the source and reservoir. Taej Mundkur comments “There is very little specific information on the source of this particular virus strain, its ecology or reservoir, and it is premature to be hypothesizing on the vectors”. Source

    That brings me to an important point. Most people are worried of eating poultry meat. Though, I personally am a pure vegetarian and dont recommend eating meat, I dont see it to be unsafe. As far as the facts are known, hygeinc and good cooking practices can kill the viral particles if present and hence shouldnt be problem. And for people who are working with poultry industry, (especially imported meat), possibly need to be watched.

ResearchBlogging.orgKageyama T, Fujisaki S, Takashita E, Xu H, Yamada S, Uchida Y, Neumann G, Saito T, Kawaoka Y, Tashiro M (2013). Genetic analysis of novel avian A(H7N9) influenza viruses isolated from patients in China, February to April 2013 Eurosurveillance, 18 (15)

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