Varicella Zoster Virus Flashcards
True or false: VZV is nationally notifiable?
Yes - routine.
Doctors notify chickenpox or shingles.
Labs notiify unspecified.
Which organism causes VZV?
Varicella zoster virus also known as human herpesvirus 3 (HHV3).
How is VZV transmitted?
- Airborne/droplet spread
- Direct/indirect contact with vesicular fluid.
Chickenpox high R0 3.7 to 5.0
What are the clinical features of chickenpox?
- Fever
- Malaise
- Itchy rash (papular 🡪 vesicular 🡪 scabs).
Usually mild and self-limiting. Can be severe, even fatal.
If vaccinated, breakthrough infection may only be maculopapular rash.
What are the clinical complications of chickenpox?
- Pneumonia
- Aseptic meningitis
- Encephalitis
Neonates 30% CFR without treatment.
What are the clinical features of shingles?
Dermatomal vesicular eruption, often preceded by severe pain.
Self-limiting, usually resolves within 2 weeks.
What are the clinical complications of shingles?
- Post-herpetic neuralgia (up to years)
- Disseminated zoster (visceral/CNS/pulmonary).
Which groups are high-risk for VZV?
- Immunocompromised
- Newborns
- Pregnant women
What are the case definitions for chickenpox?
Confirmed - isolation / detection / seroconversion OR clinical + epi
Probable (clinical only).
Unspecified: isolation/detection/seroconversion.
What are the case definitions for shingles?
Confirmed (isolation/detection AND clinical)
Probable (clinical only).
Unspecified: isolation/detection/seroconversion.
How is VZV diagnosed?
Usually clinical.
Swabs from lesions for PCR, genotyping.
For chickenpox distinguish vaccine/wild type strain if vaccinated 5-42 days prior to rash.
What is the incubation period for VZV?
Usually 14-16 days
Range 10-21 days
What is the infectious period for VZV?
Chickenpox: 48h prior to rash until all blisters are crusted.
Shingles: appearance of blisters until dried (7-10 days).
What is the outbreak definition of VZV?
≥2 cases of chickenpox with epi link
OR
≥2 cases of varicella in defined setting where onward transmission of chickenpox from case with shingles
How are outbreaks of VZV managed?
How is chickenpox prevented?
Vaccination
* NIPS at 18m (MMRV); second dose recommended ≥4 weeks later to reduce breakthrough, but not on NIPS.
* Non-immune adults
Which groups of adults should be vaccinated against chickenpox?
Non-immune adults, especially:
* Non-pregnant WCBA
* HCW
* Aged/disability carers
* Childcare workers
* HH contacts of immunocompromised
How is shingles prevented?
Vaccination - recommended for:
* immunocompetent adults ≥50yo
* immunocompromised people ≥18y.
Which vaccines are available to protect against shingles?
- Zostavax live attenuated (1 dose) - 70+
- Shingrix recombinant (2 doses) - 65+, FNs 50+ and immunocompromised
What resources are available for public health management of VZV?
No SoNG.
DH protocol.
How are cases of VZV managed?
Follow-up HCW/inpatients in immunosuppressive, obstetric, neonatal wards.
- Interview (Sx, location/coverage of shingles rash, detailed info re high-risk setting, other known cases)
- Treatment
- Isolation / exclusion - NP room + airborne precautions for chickenpox/ disseminated shingles; single room + droplet for shingles if uncovered. Case hygiene, isolate until blisters dried. Notify hospital IPC team, assist with response.
- Education
Who are considered close contacts of VZV cases?
- HH
- Face to face ≥5 mins
- Same room ≥1h.
Who are high-risk contacts of VZV cases?
- Infants < 1mo
- Pregnant women
- Immunosuppressed
How are contacts of VZV managed?
- Treatment - check immunity, PPX (some groups), vaccination (some groups)
- Isolation/Exlusion - isolate hospitalised susceptible contacts in hospital 8-21d after exposure (up to 28d if VZIG); exclude non-immune HCW and children with immune deficiency
- Monitor
- Educate re symptoms.
What is considered evidence of immunity against VZV?
- Serological evidence
- Reliable Hx chickenpox
- Evidence of vaccine
Who should receive prophylaxis (VZIG) against VZV?
VZIG for:
* Prem infants/BW < 1kg
* Non-immune pregnant women
* Immunosuppressed (consult with specialist clinicians for all).
Which contacts should receive post-exposure vaccination against VZV?
Susceptible HCW contacts: VZV vaccination within 5d (ideally 72h) of first exposure.
Which VZV contacts should be excluded from work or school?
- Non-immune HCWs - no patient contact 8-21 days after exposure unless vaccine given.
- Children with immune deficiency - exclude from school
Parents may voluntarily exclude non-vaccinated children.
Which contacts of VZV should be isolated?
Isolate hospitalised susceptible contacts in hospital 8-21d after exposure (up to 28d if VZIG).
What environmental management is required for VZV?
N/A
True or false: VZV is endemic in Australia?
True
What is the lifetime risk of shingles reactivation?
50% - risk increases with age
