Influenza, also called as 'flu' is a viral infection caused by a virus named influenza virus. This virus is typically spherical in shape, with a diameter of 80 to 120 nm (Nanometer) but pleomorphism is very common for this virus. It is common for this virus to be in filamentous form and is visible under the dark ground microscope. The virus remains viable at 0-4 degree Celsius for about a week and remains viable on fomites such as towels for about two weeks. Influenza (infection) is an acute respiratory disease which occurs in sporadic, epidemic and pandemic forms.
Source: Nature Review/ Microbiology
Influenza viruses are of three types; type A, type B and type C. Type A and type B virus infects human beings, fowl, guinea pig and some other species whereas influenza virus type C infects fowl only. Avian(bird) influenza is a disease caused by infectious avian influenza type A viruses. Based on the molecular characteristics and their ability to cause disease and mortality in chickens in a laboratory settings, Influenza type A are classified as highly pathogenicity avian influenza (HPAI) or low pathogenicity avian influenza (LPAI). Type A influenza viruses can be divided into different strains and subtypes based on the structural component ( proteins) present on the surface of the virus. The two structural protein found on the surface of the virus are called hemagglutinin and neuraminidase. Based on these proteins the virus is divided into 18 different hemagglutinin subtypes(H1 through H18) and 11 different neuraminidase subtypes (N1 through N11). For example H5N1 strain designates an influenza virus A with Hemagglutinin(HA5) and Neuraminidase(NA1)
Source: Dreamstime.com
One of the interesting feature of influenza virus that fascinated me is their ability to change constantly over a period of time. These changes are of two types called ''antigenic drift'' and ''antigenic shift''.The above figure shows the structural components in an influenza virus. Antigenic drift refers to those small changes in the genes of the viruses that takes place continually when the virus multiplies. The new virus emerged after antigenic drift is closely related to the parent strains and share most of the common properties. But over a long time these changes may accumulate together and thus the newly developed virus become different than the parent strain. This creates a problem in the influenza vaccine we administer every year. Vaccines used this year may not work for next year because of the changes that takes place in influenza virus due to "antigenic drift". This is the reason why we get flu vaccine every year. On the other hand, when the protein component (hemagglutinin and neuraminidase) of the viruses change, either one or both, new influenza virus is emerged and this process is called antigenic shift. "Such a “shift” occurred in the spring of 2009, when an H1N1 virus with a new combination of genes emerged to infect people and quickly spread, causing a pandemic"(CDC). Antigenic drift takes place very often whereas antigenic shift takes place once a while.
This peculiar characteristics of influenza virus has always created questions on the effectivity of the flu vaccines. Thus, in my latter post i will be trying to find answers to the following questions:How effective are the available vaccines?
Does the available vaccines equally effective for children, adult and old peoples?
Wow, this is crazy! I think this is so interesting. It really caught my eye and it is scary to think that you could get it. I never heard of this virus before but after reading your blog it helped me understand a lot of what it is about.
ReplyDeleteSo the first thing that grabbed my attention was the title itself. Not very often do I have to use google to look up terms. Viruses are an incredible thing to dig into. Especially talking about their ability to change and adapt over time. It is something that not many people seem to grasp about viruses, and diseases in general, is that sometimes they change. Whether it is by chance that their DNA gets altered in the replication process and the new strain is now more effective at being transmitted. Or because this new strain is now resistant to the vaccinations that we have available, and can then spread with impunity because no other viruses of its kind are able to do so.
ReplyDeleteThis is quite an interesting topic that doesn’t get a whole lot of coverage, and I am looking forward to seeing how this develops.
Informative post. Thank you for providing information regarding contemporary health issue.
ReplyDeleteThis was a good post full of a lot of information but I'm not sure exactly if you're trying to persuade any type of point. I have mixed feelings about the flu shot and I don't get one because I would rather contract it and let my body fight it naturally than take a flu shot that I don't know what is in it. I am becoming more conscious about what I put in my body and I don't even like taking over the counter medications if I don't have to. I think this is an interesting post but I think your end goal is a little unclear. I wasn't sure if your were trying to persuade me to or to not get a flu shot.
ReplyDeleteGood Job!!!
ReplyDeletePersonally, i am benefited with this huge information regarding influenza virus and become cautious on health issues (personal as well as public). Looking forward your perception regarding this issues too.
Thumbs Up!!