Jimmy has always been told that if you have chicken pox once, you will not get the disease again. he had chicken pox when he was eight, but he only had five to ten little pox blisters on his skin. as an adult, jimmy is again showing symptoms of chicken pox. using your knowledge of the human immune system, explain how this is possible.

In immunology two types of immune response are described depending on whether there is prior contact with the antigen.

• At this first contact, only lymphocytes with receptors specific to the antigen in question are stimulated and lead to the production of antibodies capable of neutralizing it. The lymphocytes capable of recognizing a specific antigen are very few and the production of antibodies - of low intensity and limited duration - is detectable only after a period of latency of several days. This is called the primary response. The specificity of the resulting seropositivity, however, makes it possible to detect contamination (seroconversion).

• Upon re-contact with an antigen that has already triggered a primary response, specific antibody production is found to increase rapidly after a short latency period. The secretion of IgG then reaches levels much higher than those observed during the primary response, while that of IgM is of the same order. This early and intense response, called secondary response, most often results in the destruction of infectious agents before any clinical sign.

• Many centuries before the discovery of microbes, it was noted that people who developed a contagious disease without death were then specifically immunized against the disease, without being protected against others.

• The ability to react appropriately to an already received stimulus supposes the existence of a memory. The immune memory is based on the existence of memory B and T lymphocytes, resulting from the clonal expansion due to the first contact with the antigen. Their lifespan is significantly higher than that of other lymphocytes and their high reactivity gives its rapid and intense character to the secondary response.

The chickenpox can reoccur in people with a weakened immune system or in individuals whose first encounter with chickenpox was mild.

Further Explanation:

Chickenpox is an infectious disease that is induced by the varicella-zoster virus (VZV). It affects babies, elderly people, and adults. It results in the formation of blisters usually on the back, face, and stomach. The people who already had chickenpox once would have antibodies for these viruses stored in the immune system. This is the reason why it cannot occur twice in any individual.

Although people with a weakened immune system are susceptible to chickenpox and may acquire the disease again. Sometimes mild rashes are misdiagnosed as chickenpox in the first instance and therefore, the actual occurrence of chickenpox in the same person is considered to be the second time.When a person is cured of chickenpox, the virus is not completely excreted out of the body but remains inactive in the nerve tissues. The reactivation of this virus may occur in the later stage of life due to stress conditions or aging of the immune system. The activation of the virus for the second time results in shingles.

The weak immune system is not able to suppress the infectious agents in the body. This might lead to the activation of the virus that cannot be kept dormant anymore. Shingles are caused by the same virus as that of chickenpox. The individual affected with shingles has infected the nerve and the skin surfaces. The symptoms for shingles are similar to that of chickenpox such as headache, fever, blister rash, pain, itching, and burning sensation. Due to the similar symptoms shingles are considered as chickenpox.

Here, in this case, due to the mild encounter of chickenpox in the first instance, Jimmy might have acquired the disease again or it might be that the first encounter was misdiagnosed as chickenpox. Jimmy might be infected with shingles as an adult which is being considered as chickenpox due to similar symptoms.

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Answer Details:

Grade: High School

Subject: Biology

Chapter: Infectious diseases

Keywords:

Chickenpox, varicella-zoster virus, shingles, immune system, antibodies, blister rash, fever, headache, itching sensation.