Varicella Zoster Flashcards
What kind of virus is the varicella-zoster virus, and what is the structure?
It is a herpes virus.
It is an enveloped, single stranded DNA virus.
What can this herpes virus do that others cannot?
It can be spread easily by person to person casual contact.
How is varicella-zoster virus spread?
It is spread through inhalation of respiratory droplets.
What does the varicella-zoster virus cause on first contact, and what is the presentation?
Chickenpox - vesicles on the skin that appear 14-21 days after exposure, that are usually very itchy. They may have:
- High temperature.
- Loss of appetite.
- Aches and pains.
What is the significance of not having chickenpox as a child, and what do clinicians do to prevent this?
The virus is much more severe in adults than it is in children.
If they are pregnant when they contract it, it can affect the foetus.
A vaccine is offered to those who have not contracted the virus as a child.
What is the treatment of chickenpox?
There is no specific treatment.
Supportive:
- Fluid.
- Anti-pyretics.
- Stop the child from scratching.
Can they become reinfected after having had varicella-zoster virus?
No, once they have had chickenpox, they contain the memory B-cells and antibodies to prevent the virus from being contracted again.
They can, however, have shingles later in life.
How does the adaptive immune system protect from the varicella-zoster virus?
The viral PAMPs are recognised by the PRRs on antigen presenting cells.
The APCs then process and present the viral antigens to CD4+ and CD8+ T-cells.
Cytotoxic T-cells, natural killer cells and phagocytes can then destroy the virus.
Antibody production from B-cells also occurs.
CD8+ memory and memory B-cells remain.
How can a patient get reinfected with the varicella-zoster virus?
The virus can be in the latent (dormant) phase, due to the T-cells.
The virus can then reactivate at any time.
What is the normal presentation of shingles?
There is often pain in a specific dermatome of the body.
This is then followed by a blistered, unilateral rash.
This rash can then last up to 4 weeks.
They may also have a headache, red and sore eyes, and their sight and hearing may be affected.
How can varicella-zoster virus come out of latency?
It is usually due to some form of immunosuppression, such as cancer and chemotherapy.
It can also occur in aging people as their T-cell function decreases.
How is shingles diagnosed?
It is usually diagnosed through the clinical presentation.
It can be diagnosed through PCR of the fluid within the blisters of the rash.
What is the treatment of shingles?
Acyclovir can be given on early onset of the rash to prevent replication of the virus (but not if towards the end of the 4 weeks).
Paracetamol may also be given for the pain.
Describe the appearance of a shingles rash.
A red, blistered rash that is localised to an area of the skin.
Who is the varicella-zoster virus vaccine given to?
70-79 year olds.
After the age of 79, it becomes less effective.
