1. An individual can be provided immediate, short-term immunity against a pathog
ID: 3511107 • Letter: 1
Question
1. An individual can be provided immediate, short-term immunity against a pathogen or toxin by injecting them with sera containing appropriate antibodies. This is called artificial passive immunity. One example would be anti-venom used to treat snake bites. Assume an individual was bitten by a snake and treated with antivenom, then bitten again a year later by the same type of snake. Would they need another injection of anti-venom, or would they still be protected?
Explain why or why not
2. After returning from traveling abroad, a patient sees his doctor because he suspects he may have been exposed to polio during his travels. An assessment of his circulating antibodies to polio indicate that he has a very high titer of IgG antibodies against the polio virus, but a significantly lower titer of IgM antibodies against the polio virus. Explain why this individual is or is not likely to be at risk for adverse effects from exposure to polio.
Explanation / Answer
1. The individual wwould need another injection of anti-venom.
Cause - The individual has received antisera containing antibodies one year earlier. But, the artifiacial passive immunity provided would have been deceased to a minimal level. Also, we can not rely on the titre of active immunity that would have been developed by the first exposure to the snake venom. So, to minimise any risk to the life of the person, we should inject another injection of anti-venom.
2. The individual is not likely to be at risk for adverse effects from exposure to polio.
Cause- The low titre of IgM antibodies signifies that there is least chance of exposure to the polio virus in the recent time, as IgM is the first antibody to appear after exposure to the pathogen. The high titre of IgG found may be due to exposure to the virus long time ago, as IgG titre rises only after a very long time of exposure.
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