Varicella-zoster virus: Difference between revisions
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| − | == |
+ | ==Background== |
| − | === |
+ | ===Microbiology=== |
| − | * dsDNA virus in the Alphaherpesvirus family, related to HSV |
||
| − | * Key glycoproteins |
||
| − | ** gB II target of neutralizing antibodies like VZIg |
||
| − | ** gC gp IV not essential |
||
| − | ** gE gp I binds Fc IgG |
||
| − | ** gH gp III fusion function |
||
| − | ** gL glycosylation |
||
| + | *dsDNA virus in the ''Alphaherpesvirinae'' subfamily within the [[Herpesviridae]] family, related to HSV |
||
| − | === Epidemiology === |
||
| + | *Key glycoproteins |
||
| − | * Varicella is more late winter or spring in temperate climates, often corresponds to school year |
||
| + | **gB II target of neutralizing antibodies like VZIg |
||
| − | * Acquired by 5-10 years old in temperate climates |
||
| + | **gC gp IV not essential |
||
| − | ** In tropical climates, more susceptibility in adults |
||
| + | **gE gp I binds Fc IgG |
||
| − | * Incubation period is [[Usual incubation period::10 to 21 days]] |
||
| + | **gH gp III fusion function |
||
| − | * Infectiousness lasts from 24h before rash (around time of fever) to the final crusting |
||
| + | **gL glycosylation |
||
| − | * Transmitted airborne, respiratory secretions; ''not'' transmitted on fomites |
||
| − | === |
+ | ===Epidemiology=== |
| − | * Transmitted by respiratory route |
||
| − | * Primary viremia infects liver and RES (~14 days) |
||
| − | * Secondary viremia causes dissemination to skin |
||
| + | *Varicella is more late winter or spring in temperate climates, often corresponds to school year |
||
| − | == Clinical Manifestations == |
||
| + | *Acquired by 5-10 years old in temperate climates |
||
| + | **In tropical climates, more susceptibility in adults |
||
| + | *Incubation period is [[Usual incubation period::10 to 21 days]] |
||
| + | *Infectiousness lasts from 24h before rash (around time of fever) to the final crusting |
||
| + | *Transmitted airborne, respiratory secretions; ''not'' transmitted on fomites |
||
| + | ===Pathophysiology=== |
||
| − | === Primary infection (varicella) === |
||
| − | * Primary infection usually benign in childhood |
||
| − | * Primary infection can be severe in adolescents, adults, and immunocompromised hosts |
||
| − | * New vesicle formation stops within 4 days |
||
| − | * Presentation modified by prior vaccination |
||
| − | ** Less severe, fewer vesicles, less classic rash |
||
| − | * Vaccine-associated: can also get infected by the vaccine strain itself |
||
| + | *Transmitted by respiratory route |
||
| − | ==== Differential Diagnosis ==== |
||
| + | *Primary viremia infects liver and RES (~14 days) |
||
| − | * [[Enterovirus]] |
||
| + | *Secondary viremia causes dissemination to skin |
||
| − | * [[Staphylococcus aureus]] |
||
| − | * Drug reactions |
||
| − | * Contact dermatitits |
||
| − | * Eczema herpeticum |
||
| − | * Insect bites |
||
| + | ==Clinical Manifestations== |
||
| − | ==== Breakthrough ==== |
||
| − | * 20% of vaccinated children still acquire varicella |
||
| − | * Milder, fewer sequelae |
||
| − | === |
+ | ===Primary Infection (Varicella)=== |
| − | * SSTI: invasive GAS including nec fasc |
||
| − | * Hepatitis, especially in immunocompromised, transplant, and AIDS (can be severe) |
||
| − | * Diarrhea, pharyngitis, otitis, nephritis, transient arthritis, myocarditis, ... |
||
| − | * Neurologic |
||
| − | ** Acute cerebellar ataxia |
||
| − | ** Diffuse encephalitis |
||
| − | ** Aseptic meningitis, transverse myelitis, strokes |
||
| − | * Reye syndrome: vomiting, excitability, delirium, and coma |
||
| − | ** Secondary to varicella and concomitant aspirin |
||
| − | * Respiratory: pneumonitis can be severe |
||
| − | ** Typically develops days after rash |
||
| − | ** Consider [[Is treated by::acyclovir]] ± [[prednisone]] |
||
| + | *Primary infection usually benign in childhood |
||
| − | ==== High-risk populations ==== |
||
| + | *Primary infection can be severe in adolescents, adults, and immunocompromised hosts |
||
| − | * Pregnancy |
||
| + | *New vesicle formation stops within 4 days |
||
| − | ** Spontaneous abortions, IUFD, prematurity |
||
| + | *Presentation modified by prior vaccination |
||
| − | ** Congenital varicella syndrome |
||
| + | **Less severe, fewer vesicles, less classic rash |
||
| − | *** Highest risk <20 weeks |
||
| + | *Vaccine-associated: can also get infected by the vaccine strain itself |
||
| − | *** Cutaneous defects, cicatral scarring and limb atrophy |
||
| − | *** Microcephaly, autonomic dysfunction |
||
| − | ** If primary varicella 5 days before to 2 days after delivery, high risk of mortality |
||
| − | * Immune-compromised hosts |
||
| − | ** Can have progressive disease with prolonged lesions and multiorgan infection |
||
| + | ====Differential Diagnosis==== |
||
| − | === Herpes zoster (shingles) === |
||
| + | *[[Enterovirus]] |
||
| − | * Varicella reactivation from dorsal root ganglia |
||
| + | *[[Staphylococcus aureus]] |
||
| − | * Dermatomal |
||
| + | *Drug reactions |
||
| − | * Herpes ophthalmaticus (CN V1) |
||
| + | *Contact dermatitits |
||
| − | * Ramsay-Hunt syndrome |
||
| + | *Eczema herpeticum |
||
| − | * Post-herpetic neuralgia |
||
| + | *Insect bites |
||
| − | ==== |
+ | ====Breakthrough==== |
| + | *20% of vaccinated children still acquire varicella |
||
| − | * Rising age predict zoster as well as postherpetic neuralgia |
||
| + | *Milder, fewer sequelae |
||
| − | ** 50% by age 85 years |
||
| − | * Post-surgery |
||
| − | * [[HIV]] (even with normal CD4) |
||
| − | * Transplant (HSCT > SOT) |
||
| − | ==== |
+ | ====Sequelae==== |
| + | *[[SSTI]] caused by secondary bacterial infection with invasive [[GAS]], and can including [[necrotizing fasciitis]] |
||
| − | * May become disseminated |
||
| + | *[[Hepatitis]], especially in immunocompromised, transplant, and advanced HIV (can be severe) |
||
| − | * Can become chronic with episodic viremia |
||
| + | *[[Diarrhea]], [[pharyngitis]], [[otitis]], [[nephritis]], transient [[arthritis]], [[myocarditis]], ... |
||
| − | * Prophylaxis |
||
| + | *Neurologic |
||
| − | ** HSCT: prophylax with valacyclovir for 1+ year following transplant (longer if GVHD) |
||
| + | **Acute cerebellar ataxia |
||
| − | ** SOT: 3-6 mo after transplant and for duration of lymphodepletion |
||
| + | **Diffuse encephalitis |
||
| + | **Aseptic meningitis, transverse myelitis, strokes |
||
| + | *[[Reye syndrome]]: vomiting, excitability, delirium, and coma |
||
| + | **Secondary to varicella and concomitant aspirin |
||
| + | *Respiratory: [[pneumonitis]] can be severe |
||
| + | **Typically develops days after rash |
||
| + | **Consider [[Is treated by::acyclovir]] ± [[prednisone]] |
||
| + | ====High-Risk Populations==== |
||
| − | == Diagnosis == |
||
| + | *Certain populations are at higher risk for severe complications |
||
| − | * PCR most common, sensitive and specific, can be tissue, serum, CSF, saliva, etc |
||
| + | *Pregnancy |
||
| − | * Multinucleated giant cells on histology |
||
| + | **[[Spontaneous abortion]], [[IUFD]], [[prematurity]] |
||
| − | * Cell culture |
||
| + | **[[Congenital varicella syndrome]] |
||
| − | * Serology |
||
| + | ***Highest risk <20 weeks |
||
| + | ***Cutaneous defects, cicatral scarring and limb atrophy |
||
| + | ***Microcephaly, autonomic dysfunction |
||
| + | **If primary varicella 5 days before to 2 days after delivery, high risk of mortality |
||
| + | *Immune-compromised hosts |
||
| + | **Can have progressive disease with prolonged lesions and multiorgan infection |
||
| + | ===Herpes Zoster (Shingles)=== |
||
| − | == Management == |
||
| − | * [[Is treated by::Valacyclovir]] preferred to [[Is treated by::acyclovir]] |
||
| − | ** Main side effect of valacylovir is headache |
||
| + | *Varicella reactivation from dorsal root ganglia |
||
| − | === Normal host === |
||
| + | *Typically a dermatomal distribution |
||
| − | * '''Primary varicella''' |
||
| + | *Herpes ophthalmaticus (CN V1) |
||
| − | ** Simple VZV infection, start ASAP (<72 hours) after onset of rash if going to treat; or, don't treat |
||
| + | *Ramsay-Hunt syndrome |
||
| − | ** If higher risk or severe sequelae, more likely to treat |
||
| + | *Post-herpetic neuralgia |
||
| − | ** 5 days in normal host |
||
| − | * '''Zoster''' |
||
| − | ** Start treatment within 72 hours to reduce new lesions (doesn't affect PHN) |
||
| + | ====Risk Factors==== |
||
| − | === Immunocompromised host === |
||
| − | * '''Primary varicella''': start with IV [[Is treaed by::acyclovir]], then step down to oral [[Is treaed by::valacyclovir]] |
||
| − | * '''Zoster''': start with IV [[Is treated by::acyclovir]], then PO with close followup, until no new lesions for 2 days (minimum 7 days) |
||
| − | * '''Pregnancy''': treat zoster if more than 50 lesions |
||
| − | * '''Ophthalmic zoster''' should be treated (involve Ophtho) |
||
| − | * '''Acute retinal necrosis''': IV [[Is treaed by::acyclovir]] for 10 to 14 days, with steroids (involve Ophtho) |
||
| − | * '''Ramsay Hunt syndrome''': PO antiviral with prednisone |
||
| + | *Rising age predict zoster as well as postherpetic neuralgia |
||
| − | == Prevention == |
||
| + | **50% by age 85 years |
||
| + | *Post-surgery |
||
| + | *[[HIV]] (even with normal CD4) |
||
| + | *Transplant (HSCT > SOT) |
||
| + | ====Disseminated Zoster==== |
||
| − | === Post-exposure management === |
||
| − | * Identify contacts: very long list, includes anyone with 5 minutes of face-to-face time, adjacent rooms or beds, ... |
||
| − | ** Infectious 1-2 days before onset of rash |
||
| − | * '''Isolation''' of contacts |
||
| − | ** Exposed patients without evidence of immunity should be discharge as soon as possible |
||
| − | ** If not discharged, isolate them starting 8 days from exposure (in airborne) |
||
| − | ** Duration of isolation 21 days; if VZIg (or IVIg), extend duration of isolation to 28 days |
||
| − | ** i.e. day 8 to 21 if no VZIg, day 8 to 28 if VZIg |
||
| − | * '''Post-exposure vaccination''' |
||
| − | ** Recommended for everyone, assuming that there is no documented immunity and there is no contraindication |
||
| − | ** Within 3-5 days post-exposure |
||
| − | * '''VZIg''' (or IVIg, if VZIg not available) |
||
| − | ** Indications |
||
| − | *** Immune-compromised without evidence of immunity |
||
| − | *** Pregnant woman without evidence of immunity |
||
| − | *** Child of mother she had primary chicken pox 5 days before to 2 days after delivery |
||
| − | *** Preterm >28 days without evidence of immunity |
||
| − | *** Preterm <28 weeks gestation |
||
| − | *** HSCT who have not had their vaccine post-transplant |
||
| − | ** Start within 10 days after exposure |
||
| + | *May become disseminated in immunocompromised patients, typically after transplantation |
||
| − | === Vaccination === |
||
| + | **Involvement of visceral organs, or |
||
| + | **Multidermatomal involving 3 or more dermatomes |
||
| + | *Can become chronic with episodic viremia |
||
| + | *Prophylaxis |
||
| + | **HSCT: prophylax with [[valacyclovir]] for 1+ year following transplant (longer if GVHD) |
||
| + | **SOT: 3-6 mo after transplant and for duration of lymphodepletion |
||
| − | == |
+ | ==Diagnosis== |
| − | * Live attenuated varicella vaccine at 12 months then again at 4 to 6 years |
||
| − | * Can use for PEP if within 3 days of exposure to reduce severity and duration |
||
| − | * Live vaccine, so must be at least 12 months |
||
| − | * Two doses 90% effective, though can wane over time |
||
| − | * Adverse effects |
||
| − | ** Injection site reaction 20% |
||
| − | ** Rash with 2-5 lesions (1-3%) or generalized within 1 month (3-5%); it is infectious |
||
| − | ** Febrile seizures: MMR + VZV at 12 months has higher risk of febrile seizures |
||
| − | ** Disseminated, including meningitis |
||
| − | * See the [https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-24-varicella-chickenpox-vaccine.html Canadian Immunization Guide] |
||
| + | *PCR most common, sensitive and specific, can be tissue, serum, CSF, saliva, etc |
||
| − | ==== Zoster ==== |
||
| + | *Multinucleated giant cells on histology |
||
| − | * '''Shingrix''' (non-live recombinant; 2 doses, 6 months apart; '''more effective''') and '''Zostavax''' (live attenuated, 1 dose) |
||
| + | *Cell culture |
||
| − | ** If Zostavax, give Shingrix after 7 years as a booster |
||
| + | *Serology |
||
| − | ** If recent zoster, wait three years after an episode |
||
| − | ** Zostavax-induced immunity wanes fairly quickly while Shingrix-induced immunity appears to be much more durable |
||
| − | * Indicated in all people ≥50 years old to reduce risk of zoster and PHN |
||
| − | ** History of VZV or vaccination doesn't matter, everyone can get it |
||
| − | * See the [https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-8-herpes-zoster-(shingles)-vaccine.html Canadian Immunization Guide] |
||
| + | ==Management== |
||
| + | |||
| + | *[[Is treated by::Valacyclovir]] preferred to [[Is treated by::acyclovir]] |
||
| + | **Main side effect of valacylovir is headache |
||
| + | **Ideally started early, within 72 hours of symptom onset |
||
| + | |||
| + | ===Normal host=== |
||
| + | |||
| + | *'''Primary varicella''' |
||
| + | **Simple VZV infection, start ASAP (<72 hours) after onset of rash if going to treat; or, don't treat |
||
| + | **If higher risk or severe sequelae, more likely to treat |
||
| + | **5 days in normal host |
||
| + | *'''Zoster''' |
||
| + | **Start treatment within 72 hours to reduce new lesions (doesn't affect PHN) |
||
| + | |||
| + | ===Immunocompromised host=== |
||
| + | |||
| + | *'''Primary varicella''': start with IV [[Is treated by::acyclovir]], then step down to oral [[Is treaed by::valacyclovir]] |
||
| + | *'''Herpes zoster''': start with IV [[Is treated by::acyclovir]], then PO with close followup, until no new lesions for 2 days (minimum 7 days) |
||
| + | *'''Pregnancy''': treat zoster if more than 50 lesions |
||
| + | *'''Ophthalmic zoster''' should be treated (involve Ophtho) |
||
| + | *'''Acute retinal necrosis''': IV [[Is treated by::acyclovir]] for 10 to 14 days, with steroids (involve Ophtho) |
||
| + | *'''Ramsay Hunt syndrome''': PO [[Is treated by::acyclovir]] or [[Is treated by::valacyclovir]], with prednisone |
||
| + | *'''CNS disease''': IV [[Is treated by::acyclovir]] for 10 to 14 days |
||
| + | |||
| + | ==Prevention== |
||
| + | |||
| + | ===Infection Prevention and Control=== |
||
| + | |||
| + | *Airborne isolation required for primary varicella and disseminated zoster |
||
| + | |||
| + | ===Post-Exposure Management=== |
||
| + | |||
| + | *Identify contacts: very long list, includes anyone with 5 minutes of face-to-face time, adjacent rooms or beds, ... |
||
| + | **Infectious 1-2 days before onset of rash |
||
| + | *'''Isolation''' of contacts |
||
| + | **Exposed patients without evidence of immunity should be discharge as soon as possible |
||
| + | **If not discharged, isolate them starting 8 days from first exposure (in airborne) |
||
| + | **Duration of isolation 21 days; if VZIg (or IVIg), extend duration of isolation to 28 days |
||
| + | **i.e. day 8 to 21 if no VZIg, day 8 to 28 if VZIg |
||
| + | *'''Post-exposure vaccination''' |
||
| + | **Recommended for '''all susceptible''' exposed individuals, assuming that there is no documented immunity and there is no contraindication |
||
| + | **Within 3-5 days post-exposure to prevent disease (or any time because they need vaccination anyway) |
||
| + | *'''VZIg''' (or IVIg, if VZIg not available) |
||
| + | **Indicated ''only'' for '''susceptible''' individuals with significant '''exposure''' who are at '''high risk''' of poor outcome and have a '''contraindication''' to vaccination |
||
| + | ***That is, anyone who is already fully vaccinated or is eligible for vaccination is ineligible for VZIg |
||
| + | ***If their serostatus is unknown and can be checked within 96 hours, then do that first (except for patients with HSCT, who get immunized regardless) |
||
| + | **High risk groups include: |
||
| + | ***Neonates exposed to mother who had onset of varicella 5 days before to 2 days after delivery |
||
| + | ***Infant in NICU who is [[preterm]] <28 weeks or weighs <1000 g, regardless of maternal immunity |
||
| + | ***[[Pregnancy]] (again, only if susceptible) |
||
| + | ***Immunocompromised individuals, including [[HIV]] with CD4 <200 or <15% |
||
| + | ***[[HSCT]] who have not completed their vaccines post-transplant, regardless of prior immunity |
||
| + | **Significant contact includes: |
||
| + | ***Continuous household contact |
||
| + | ***Indoors for more than 1 hour, including same hospital room |
||
| + | ***15 minutes face-to-face contact |
||
| + | ***Touch lesions, clothes, or bedsheets |
||
| + | **Start within 4 days of exposure to prevent disease, or within 10 days of exposure to attenuate it |
||
| + | |||
| + | ===Vaccination=== |
||
| + | |||
| + | ====Varicella==== |
||
| + | |||
| + | *Live attenuated varicella vaccine at 12 months then again at 4 to 6 years |
||
| + | *Can use for PEP if within 3 days of exposure to reduce severity and duration |
||
| + | *Live vaccine, so must be at least 12 months |
||
| + | *Two doses 90% effective, though can wane over time |
||
| + | *Adverse effects |
||
| + | **Injection site reaction 20% |
||
| + | **Rash with 2-5 lesions (1-3%) or generalized within 1 month (3-5%); it is infectious |
||
| + | **Febrile seizures: MMR + VZV at 12 months has higher risk of febrile seizures |
||
| + | **Disseminated, including meningitis |
||
| + | *See the [https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-24-varicella-chickenpox-vaccine.html Canadian Immunization Guide] |
||
| + | |||
| + | ====Zoster==== |
||
| + | |||
| + | *Vaccination prevents episodes of herpes zoster (HZ) as well as decreasing post-herpetic neuralgia (PHN) |
||
| + | *Indicated in all people ≥50 years old to reduce risk of zoster and PHN |
||
| + | **History of VZV or vaccination doesn't matter, everyone should get it |
||
| + | *In Canada, preferentially use Shingrix, as it is more effective than the live vaccine |
||
| + | **If received Zostavax, wait at least 1 year before giving a booster with Shingrix |
||
| + | **If recent episode of HZ, wait at least 1 year before vaccinating |
||
| + | *See the [https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-4-active-vaccines/page-8-herpes-zoster-(shingles)-vaccine.html Canadian Immunization Guide] |
||
| + | |||
| + | {| class="wikitable" |
||
| + | ! |
||
| + | !Recombinant |
||
| + | !Live Attenuated |
||
| + | |- |
||
| + | |Brand Name |
||
| + | |Shingrix |
||
| + | |Zostavax II |
||
| + | |- |
||
| + | |Schedule |
||
| + | |2 doses, 2-6 months apart |
||
| + | |1 dose |
||
| + | |- |
||
| + | |Effectiveness |
||
| + | |>90% for HZ and PHN, and persists over time |
||
| + | |50-70% for HZ and 70% for PHL, but decreases significantly by 5 years |
||
| + | |}<br /> |
||
[[Category:Herpesviridae]] |
[[Category:Herpesviridae]] |
||
Latest revision as of 12:18, 7 January 2023
Background
Microbiology
- dsDNA virus in the Alphaherpesvirinae subfamily within the Herpesviridae family, related to HSV
- Key glycoproteins
- gB II target of neutralizing antibodies like VZIg
- gC gp IV not essential
- gE gp I binds Fc IgG
- gH gp III fusion function
- gL glycosylation
Epidemiology
- Varicella is more late winter or spring in temperate climates, often corresponds to school year
- Acquired by 5-10 years old in temperate climates
- In tropical climates, more susceptibility in adults
- Incubation period is 10 to 21 days
- Infectiousness lasts from 24h before rash (around time of fever) to the final crusting
- Transmitted airborne, respiratory secretions; not transmitted on fomites
Pathophysiology
- Transmitted by respiratory route
- Primary viremia infects liver and RES (~14 days)
- Secondary viremia causes dissemination to skin
Clinical Manifestations
Primary Infection (Varicella)
- Primary infection usually benign in childhood
- Primary infection can be severe in adolescents, adults, and immunocompromised hosts
- New vesicle formation stops within 4 days
- Presentation modified by prior vaccination
- Less severe, fewer vesicles, less classic rash
- Vaccine-associated: can also get infected by the vaccine strain itself
Differential Diagnosis
- Enterovirus
- Staphylococcus aureus
- Drug reactions
- Contact dermatitits
- Eczema herpeticum
- Insect bites
Breakthrough
- 20% of vaccinated children still acquire varicella
- Milder, fewer sequelae
Sequelae
- SSTI caused by secondary bacterial infection with invasive GAS, and can including necrotizing fasciitis
- Hepatitis, especially in immunocompromised, transplant, and advanced HIV (can be severe)
- Diarrhea, pharyngitis, otitis, nephritis, transient arthritis, myocarditis, ...
- Neurologic
- Acute cerebellar ataxia
- Diffuse encephalitis
- Aseptic meningitis, transverse myelitis, strokes
- Reye syndrome: vomiting, excitability, delirium, and coma
- Secondary to varicella and concomitant aspirin
- Respiratory: pneumonitis can be severe
- Typically develops days after rash
- Consider acyclovir ± prednisone
High-Risk Populations
- Certain populations are at higher risk for severe complications
- Pregnancy
- Spontaneous abortion, IUFD, prematurity
- Congenital varicella syndrome
- Highest risk <20 weeks
- Cutaneous defects, cicatral scarring and limb atrophy
- Microcephaly, autonomic dysfunction
- If primary varicella 5 days before to 2 days after delivery, high risk of mortality
- Immune-compromised hosts
- Can have progressive disease with prolonged lesions and multiorgan infection
Herpes Zoster (Shingles)
- Varicella reactivation from dorsal root ganglia
- Typically a dermatomal distribution
- Herpes ophthalmaticus (CN V1)
- Ramsay-Hunt syndrome
- Post-herpetic neuralgia
Risk Factors
- Rising age predict zoster as well as postherpetic neuralgia
- 50% by age 85 years
- Post-surgery
- HIV (even with normal CD4)
- Transplant (HSCT > SOT)
Disseminated Zoster
- May become disseminated in immunocompromised patients, typically after transplantation
- Involvement of visceral organs, or
- Multidermatomal involving 3 or more dermatomes
- Can become chronic with episodic viremia
- Prophylaxis
- HSCT: prophylax with valacyclovir for 1+ year following transplant (longer if GVHD)
- SOT: 3-6 mo after transplant and for duration of lymphodepletion
Diagnosis
- PCR most common, sensitive and specific, can be tissue, serum, CSF, saliva, etc
- Multinucleated giant cells on histology
- Cell culture
- Serology
Management
- Valacyclovir preferred to acyclovir
- Main side effect of valacylovir is headache
- Ideally started early, within 72 hours of symptom onset
Normal host
- Primary varicella
- Simple VZV infection, start ASAP (<72 hours) after onset of rash if going to treat; or, don't treat
- If higher risk or severe sequelae, more likely to treat
- 5 days in normal host
- Zoster
- Start treatment within 72 hours to reduce new lesions (doesn't affect PHN)
Immunocompromised host
- Primary varicella: start with IV acyclovir, then step down to oral valacyclovir
- Herpes zoster: start with IV acyclovir, then PO with close followup, until no new lesions for 2 days (minimum 7 days)
- Pregnancy: treat zoster if more than 50 lesions
- Ophthalmic zoster should be treated (involve Ophtho)
- Acute retinal necrosis: IV acyclovir for 10 to 14 days, with steroids (involve Ophtho)
- Ramsay Hunt syndrome: PO acyclovir or valacyclovir, with prednisone
- CNS disease: IV acyclovir for 10 to 14 days
Prevention
Infection Prevention and Control
- Airborne isolation required for primary varicella and disseminated zoster
Post-Exposure Management
- Identify contacts: very long list, includes anyone with 5 minutes of face-to-face time, adjacent rooms or beds, ...
- Infectious 1-2 days before onset of rash
- Isolation of contacts
- Exposed patients without evidence of immunity should be discharge as soon as possible
- If not discharged, isolate them starting 8 days from first exposure (in airborne)
- Duration of isolation 21 days; if VZIg (or IVIg), extend duration of isolation to 28 days
- i.e. day 8 to 21 if no VZIg, day 8 to 28 if VZIg
- Post-exposure vaccination
- Recommended for all susceptible exposed individuals, assuming that there is no documented immunity and there is no contraindication
- Within 3-5 days post-exposure to prevent disease (or any time because they need vaccination anyway)
- VZIg (or IVIg, if VZIg not available)
- Indicated only for susceptible individuals with significant exposure who are at high risk of poor outcome and have a contraindication to vaccination
- That is, anyone who is already fully vaccinated or is eligible for vaccination is ineligible for VZIg
- If their serostatus is unknown and can be checked within 96 hours, then do that first (except for patients with HSCT, who get immunized regardless)
- High risk groups include:
- Neonates exposed to mother who had onset of varicella 5 days before to 2 days after delivery
- Infant in NICU who is preterm <28 weeks or weighs <1000 g, regardless of maternal immunity
- Pregnancy (again, only if susceptible)
- Immunocompromised individuals, including HIV with CD4 <200 or <15%
- HSCT who have not completed their vaccines post-transplant, regardless of prior immunity
- Significant contact includes:
- Continuous household contact
- Indoors for more than 1 hour, including same hospital room
- 15 minutes face-to-face contact
- Touch lesions, clothes, or bedsheets
- Start within 4 days of exposure to prevent disease, or within 10 days of exposure to attenuate it
- Indicated only for susceptible individuals with significant exposure who are at high risk of poor outcome and have a contraindication to vaccination
Vaccination
Varicella
- Live attenuated varicella vaccine at 12 months then again at 4 to 6 years
- Can use for PEP if within 3 days of exposure to reduce severity and duration
- Live vaccine, so must be at least 12 months
- Two doses 90% effective, though can wane over time
- Adverse effects
- Injection site reaction 20%
- Rash with 2-5 lesions (1-3%) or generalized within 1 month (3-5%); it is infectious
- Febrile seizures: MMR + VZV at 12 months has higher risk of febrile seizures
- Disseminated, including meningitis
- See the Canadian Immunization Guide
Zoster
- Vaccination prevents episodes of herpes zoster (HZ) as well as decreasing post-herpetic neuralgia (PHN)
- Indicated in all people ≥50 years old to reduce risk of zoster and PHN
- History of VZV or vaccination doesn't matter, everyone should get it
- In Canada, preferentially use Shingrix, as it is more effective than the live vaccine
- If received Zostavax, wait at least 1 year before giving a booster with Shingrix
- If recent episode of HZ, wait at least 1 year before vaccinating
- See the Canadian Immunization Guide
| Recombinant | Live Attenuated | |
|---|---|---|
| Brand Name | Shingrix | Zostavax II |
| Schedule | 2 doses, 2-6 months apart | 1 dose |
| Effectiveness | >90% for HZ and PHN, and persists over time | 50-70% for HZ and 70% for PHL, but decreases significantly by 5 years |
