Question

Chickenpox is a diseae of children and young adults caused by herpes virus 3 (varicella). It is characterized by a rash of fluid filled vesicles that eventually become crusty. The rash starts on the trunk ad spreads to the extremities. Illness usually resolves in 7-10 days, and the patient becomes immune to the disease. However, some individuals later in life (over 60 years old) develop a painful disease called shingles caused by the same virus even if they have never been reexposed to the virus. The lesions are tender, persistent vesicles that form on the skin. Propose a plausible explanation, considering the age of the shingles victim and the occurence of severe pain in this illness, for how they contracted shingles and why the lesions are painful.

Answer 1

The reason why one person could be re-affected is because once you have been in contact with the virus (varicella) this virus stays latent in the host and as being part of the family of Alfaherpesvirinae it can be re-activated, even if had been a long time since the first contact.

The exact mechanism by how the virus is re-activated it has not be elucitated but it is known that it is relates with a decrease of the celular inmunity of the host, so inmunodepressed persons (like HIV patients) are more sensitive to present the shingles, now, many elderly people development this condition because of the alteraciones of the inmune system causes by getting older, phenomenoum known as inmunosenescense, which means that their inmune system does not function propiartely making them more suscetible to develop shingles.

Now, once the virus is reactivaded affects the craneal and sip al sensory ganglia which explains the highly pain that the shingles causes to the patients mainlly in the acute phase of the disease.