Anonymous asked in HealthDiseases & ConditionsInfectious Diseases · 1 decade ago

Immunity to West Nile Virus?

Once someone has had the illness, West Nile Virus, are we immune to a second infection, or can you keep getting it every time you are bitten by an infected mosquito? Thanks.

9 Answers

  • 1 decade ago
    Favorite Answer

    You are never guaranteed lifelong immunity form an infection you have recovered from. The immunity is usually temporary which is the rational behind getting booster shots for many vaccines. While it is highly unlikely to get the same infection back to back, it is not so uncommon to get the same infection more than once in a lifetime. Here is part of an answer I gave to a similar question regarding whether viruses can infect twice:

    "While it is often more difficult to contract the same infection, yes, you can contract the same pathogen twice

    The reason it is more difficult to contract an certain infection for a second time is because the immune system has memory. When you first are infected, your immune system takes several days producing cells that are uniquely specific to that pathogen and subsequently destroy the infection (hopefully!). After the infection, a fair amount of these cells (and their products) stick around in the body and are called memory cells. If the same pathogen enters the body again, the immune system does have to worry about taking so much time to produce new cells since you already have a large number lying around from the first infection

    However, the cells that stay in the body after infection have a limited life span in most cases. If a long enough period of time goes by, most of these cells may die off. If you were then to be infected, you would be starting again from scratch and you would get sick. This is the reason you get booster shots for a lot of vaccines. Vaccines work by creating the same sort of memory described above, but without the hassle of actually having to get sick! However, as mentioned, the protection eventually runs out, and you have to get a booster to get the level of memory cells up again."

  • hemond
    Lv 4
    4 years ago

    West Nile Virus Immunity

  • Anonymous
    5 years ago

    It depends, have they had the shot before? If they have had the shot before they recommend getting the vacination every year. If the horse has never had the vaccine and has been through two seasons of West Nile odds are they have been exposed and have natural immunity to it. What concerns me about the drug is the lack of valid testing. If you take 100 horses and shoot them full of West Nile, they figure only 30% will get it. Of that 30% (33 horses) maybe 50% will show clinical signs. Out of those 16 horses, maybe 4 will be so affected they have to be put down. Maybe. Still seems pretty bad right? In testing the vaccine, they draw blood after they give the vaccine. The vaccine should produce a measurable amount of antibodies to the virus (IGM). But they have never been able to do that. A horse that gets the virus naturally will develop antibodies. A horse that gets the vaccine - no matter how many times - will never show an increase in antibodies. So how can they run a controlled test? There is no way that they can. They can't tell if the vaccine worked. And since not every horse that comes in contact with the virus actually contracts it, you can't tell what horses still had the virus but did not get sick. So as a result you get a bunch of drug companies that are banking in on a drug that probably doesn't do much. If only about 5% actually die from West Nile naturally, then it makes sense that the vaccine protects 95% of the horses that get it. If anyone remembers the BS that came with the Potomac Horse Fever vaccine you know that the drug companies aren't above telling a lie to make some money. They like to use lines like, "It isn't perfect, but it is the best thing we have at the moment."

  • 5 years ago

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    Honestly I would look at the area you live in and judge the conditions. Some areas of the country have much higher rates of infection then others, and some places have yet to have a single case reported. that being said.. Prevenile's web site is a bit misleading. It claims a 12 month duration from a single injection and 100 % protection. But if you read further the 100% protection isn't to west nile, Its to viremia and fever that the protection extends. 95% protection to west nile and it takes a minimum of 28 days to build the immunity, the study info did not mention how many horses were tested, nor how many had actual immunity at 28 days latter in their data and info it states that only 89 % were protected at 12 months. Another major point of worry is this in "cutting edge technology" IE brand new. They are using Chimera Live virus's. A chimera is a blending of two different strands of DNA or two different virus strings to create a entirely different being. Supposedly this is what causes the increased immune response of this vaccine. All their science aside, virus's being what they are and prone to mutate at the drop of a hat, I would be weary of giving a already bad virus any reason at all to mutate into something far worse. And injecting this Live monster into a living body does Not sound wise at all.. Some times Science and technology forgets to ask the two most basic questions No matter what it is your thinking ask yourself Can we do it? and if the answer is Yes, then ask yourself Should we do it? then think hard on it.

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  • 4 years ago


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  • 6 years ago

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    Immunity to West Nile Virus?

    Once someone has had the illness, West Nile Virus, are we immune to a second infection, or can you keep getting it every time you are bitten by an infected mosquito? Thanks.

    Source(s): immunity west nile virus:
  • 1 decade ago

    Once you've had West Nile, you're assumed to have lifeling immunity. It's possible, however, that many years later, that your immunity level could decrease..

  • 4 years ago

    I was told by the health dept that my blood test indicated that I have had west nile more than once. who knows.

  • 1 decade ago

    their is not enough evidence to prove this so try not to get bit or have a blood transfusions!!!!!

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