varicella zoster Flashcards
What is the eclipse phase?
period from virus entry to when new infectious virions are released
What is the incubation period?
the interval between exposure and the appearance of a sign of infection
What is the prodrome?
non-specific symptoms which appear before more specific features
What is Ro?
Reproductive number, average number of secondary cases arising from one case (in totally susceptible population)
What is the name of the family which varicella zoster belongs to?
herpesviridae
What are some features of the herpesviridae family?
large double stranded dna genome, icosahedral capsid, lipid envelope derived from host cell bearing virus encoded glycoproteins, highly species specific
Which herpes virus subfamily contains HSV-1, HSV-2 and VSV?
alphaherpesviridae
Which herpes virus is genital and which is oral?
HSV-1 = oral, HSV-2 = genital
What are the betaherpesvirinae?
subfamily that only cause illness in immunocompromised hosts or fetuses, eg CMV
Name two gammaherpesvirinae, associated with malignancy
epstein-barr, human herpesvirus 8
What is the difference between latent and lytic infection?
Lytic: host cells are productively infected, new virions made
Latent: after primary infection, virus persist in cells, no new virions made
Which antibody indicates herpesviridae infection?
IgG +ve
Name two antiviral agents that inhibit DNA polymerase and control productive herpes infections (cannot eradicate latent)
aciclovir
ganciclovir
Where is VSV latent infection found?
dorsal root or cranial nerve ganglia
How does reactivation of VSV occur?
virus travels down sensory nerves, produces painful vesicle in dermatome
What is the incubation period of varicella?
10 - 21 days
What is the prodrome of varicella?
fever, pharyngitis, malaise
Complete this:
Macule–> papule –>……..–> pustule –> …..
vesicle, , crusts
What are some complications of varicella?
haemorrhagic varicella (bleed into lesions, found in immunocompromised), pneumonia (adults), acute cerebellar ataxia (children), encephalitis, secondary bacterial infection
What is the difference between an exanthem and enanthem?
an exanthem is a rash on the outside of the body, an enanthem is on the inside of the body, e.g mucus membranes
Which antibodies persist after VZV infection>
VZV IgG and IgA
Which immune cells control latent VZV
t cells
What are some clinical features of zoster?
unilateral, 1-2 dermatomes involved
what are some potential complications of zoster?
involvement of eye (opthalmic division of trigeminal nerve) leading to acute retinal necrosis, post-herpetc neuralgia, vasculopathy, meningitis, meningoencephalitis, myelopathy, cerebellitis
