View source for Acute herpes zoster

==Background==
[[File:Dermatoms alt.png|thumb|Sensory dermatomes by spinal level.]]
*Also known as shingles
*Caused by [[varicella zoster virus]] (VZV; also known as Human Herpes Virus 3) causing [[Varicella]] (chicken pox) and later zoster (shingles) 
*Virus is dormant in dorsal root ganglion and reactivates causing characteristic vesiculopapular rash in dermatomal distribution 
*Occurs once immunity to virus declines (elderly, immunosuppressed, post transplant, HIV)

===Prevention===
*Patient is contagious until lesions are crusted over 
*Consider varicella-zoster immunoglobulin to immunosupressed, pregnant, neonate contacts
*Zoster vaccination if >60

{{Herpes viruses}}

==Clinical Features==
[[File:Zoster.jpeg|thumb|Herpes Zoster]]
[[File:Shingles.jpg|thumb|Herpes Zoster]]
*Prodrome: [[Headache]], [[Weakness|malaise]], photophobia 
*Antecedent [[pruritus]], [[paresthesia]], pain to dermatome 2-3 days prior to rash 
*Maculopapular [[rash]] (see below) progresses to vesicles, may coalesce to bullae, in dermatomal distribution lasting 10-15 days 
*Does not cross midline 
*Typically affects chest/face
*Lumbar and sacral dermatomes may display skin sparing between the feet and groin
*V3 involvement can present initially as dental pain
[[File:Herpes Zoster.jpg|thumb]]

==Differential Diagnosis==
{{Bullous rashes DDX}}
{{VZV types}}

==Evaluation==
===Workup===
*Generally a clinical diagnosis
*May consider viral Culture, antigen, PCR of vesicle fluid

===Evaluation===
*Confirm that the patient does not have:
**[[Herpes zoster ophthalmicus]] 
**[[Herpes zoster oticus]] (Ramsay Hunt syndrome)
*Consider further evaluation for immunocompromized state (may be initial presentation of [[HIV]]) if:
**Disseminated
***For skin, disseminated is defined as more than 20 lesions outside the primary and adjacent dermatomes<ref>Bolognia, J. L., Schaffer, J. V., & Cerroni, L. (n.d.). Dermatology: 2-Volume Set. Elsevier.3 or more dermatomes affected.</ref>
***Can also disseminate to other organs including liver, lung, and brain.
**Atypical illness/severe disease 
*In immunocompromised patients consider further evaluation for:
**Pneumonitis
**[[Hepatitis]]
**[[Encephalitis]]

==Management==
===[[Analgesia]]===
*Analgesia is very important and should be prescribed along with an antiviral
*Consider [[lidocaine]] patch, [[NSAIDS]], oral [[opioids]], or [[gabapentin]]
*[[Diphenhydramine]] and [[ranitidine]] for itch/pain

===[[Antivirals]]===
*Reduces risk/duration of [[postherpetic neuralgia]] with dosing based on immune status and time course of disease
*Not effective in treating postherpetic neuralgia once it has developed
'''Immunocompetent patients:'''
*[[Acyclovir]] 800mg PO 5x/day x 7d if <72hr of onset of rash or >72hr if new vesicles present/developing<ref>Cohen, J. Herpes Zoster. N Engl J Med 2013; 369:255-263. DOI: 10.1056/NEJMcp1302674</ref> 
*[[Valacyclovir]] (can also be given but is generally more expensive than acyclovir)
**1g PO q8hrs (CrCl normal)
**1g PO q12hrs (CrCl 30-49 mL/min)
**1g PO q24hrs (CrCl 10-29 mL/min(
**500mg q24hrs PO (CrCl < 10ml/min)
'''Immunosuppressed patients:'''
*Antiviral therapy should be given regardless of the time of onset of rash 
*[[Acyclovir]] 10mg/kg IV q8h OR 800mg PO 5x/day x 7d or [[Foscarnet]] for acyclovir-resistant VZV, disseminated zoster, CNS involvement, ophthalmic involvement, advanced AIDS, or recent transplant
*Isolation precautions
**Disseminated zoster requires airborne precautions

===[[Glucocorticoids]]===
*Steroids ''not'' shown to be beneficial<ref>He L, Zhang D, Zhou M, Zhu C. Corticosteroids for preventing postherpetic neuralgia. Cochrane Database Syst Rev. 2008.</ref>

==Disposition==
*Admit for disseminated VZ, CNS involvement, severely immunosuppressed
*Healing of lesions may take 4 or more weeks<ref>Sampathkumar P, et al. Herpes zoster (shingles) and postherpetic neuralgia. Mayo Clin Proc. 2009; 84(3):274–280.</ref>

==Complications==
*[[Postherpetic neuralgia]] (risk increases with age)
*[[Cellulitis]]
*[[Impetigo]]
*[[Necrotizing Fasciitis]]
*[[SIADH]]

==See Also==
*[[Postherpetic neuralgia]]
*[[Herpes zoster ophthalmicus]]
*[[Herpes zoster oticus]] (Ramsay Hunt syndrome)
*[[Generalized rashes]]

==References==
<references/>

[[Category:ID]]