Herpes Virus Flashcards
How many herpes viruses are there?
8
Name the herpes viruses that affect humans?
Herpes simplex 1 Herpes simplex 2 varicella Zoster virus Cytomegalovirus Epstein Barr Virus Human herpes virus 6 Human herpes virus 7 Human herpes virus 8 (karposis sarcoma associated herpes virus)
How are herpes virus transmitted?
Saliva in asymptomatic and symptomatic individuals
Why are herpes virus often presented to you as a dentist?
Most can present as oral lesions
Describe herpes virus structure
Enveloped acquired from host cell
DS DNA
What are the 2 stages of herpes virus infection? describe each
Lytic infection and latent infection
Lytic - actively replicating new viruses produced causing host cell to burst and die
Latent = dormant in host cell - no active replication
Describe general life cycle of herpes simplex virus 1 and 2
- During primary infection the virus is exposed to epithelial cells where is attaches
- Capsid containing double stranded DNA is released into cytoplasm
- DS DNA moves in nucleus where new prodigy viruses are produced
- new viruses released from cell during lysis
- released in vesicles contains highly infectious fluid (also found in saliva)
- when the infection is under control from immune system some prodigy viruses will travel up sensory neurones to the spinal ganglia where they sit dormant until reactivated and they travel back to epithelial cells
Describe primary infection?
First infection with either HSV1 or 2 causing active viral replication in mucosal tissues.
Normally symptomatic but can be asymptomatic
Describe latency?
Virus sits in nerve cell bodies in spinal cord with no viral replication
Describe reactivation?
Latent virus reactivates and active viral replication in mucosal tissues resumes
At what age do most primary infections occur in UK?
Before 5
What is the seroprevalence of HSV1 and HSV2 in UK?
1 = 50-70% 2 = 10%
How is HSV spread?
Oral - close contact e.g. kissing
Genitals - sexual contact
From mother to baby
Describe oral manifestion of primary HSV infection?
a) what virus
b) symptoms - sytemically
c) symptoms - orally
d) complications
a) Most commonly HSV1 but can be HSv2
b) usually asymptomatic
c) severe gingivostomatitis
d) may require hospitalisation due to dehydration or pain
Oral reactivation of HSV1?
Cold sores - rarely intra-oral
Oral reactivation of HSV2?
Generally doesn’t reactivate
Oral reactivation of HSV
a) cause
b) triggers
c) sensation
d) duration
a) unknown
b) stress, fever, menstruation, cold, UV
c) tingling or itching
d) 5-12 days
HSV genital disease
a) primary infection
b) reactivation agent
c) primary vs reactivation severity
a) HSV1 or HSV2
b) HSV2 only
c) primary is more severe, reactivation is usually asymptomatic
Why can HSV genital disease be spread unknowingly?
Reactivation is often asymptomatic
Main complications of HSV?
Secondary bacterial infection - rash destroys epithelia so bacteria can penetrate
Corneal ulcers - loss of vision, risk of scarring
Meningitis - self limiting, HSV2, can be recurrent (mollarets meningitis)
Herpes simplex encephalitis, life-threatening, usually HSV1
Neonatal hepres simplex - life threatening
Life threatening infection in immunocompromised
What is herpetic whitlow?
Lesions on thumb or fingers due to herpes simplex virus
What type of people are susceptible to herpetic whitlow?
Thumb suckers - infected saliva penetrates skin
Occupational health hazard when correct PPE not used
How can HSV affect the eye?
Occular infection - corneal ulcers - need to be treated promptly or scarring and loss of vision
What causes neonatal infection?
Directly through birthing process - if mother infected with HSV, could be secreted in vaginal fluid and infect the baby
Or infected family ember kissing baby shortly after birth
