Jama 2009;302:73 (zoster); Nejm 2002;347:340; 2000;342:635 (zoster); Ann IM 1999;130:922

Cause:Varicella, a herpesvirus

Pathophys:Same organism causes 1st chickenpox, and later shingles (Nejm 1984;311:1362)

Zoster: more common in the elderly and pts w HIV and cancer but not a si of occult malignancy; 10-20% of all persons will have in lifetime

Cpox: <10% repeat infections, probably quite rare (Jama 1997;278:1520); dramatic drop in US mortality after 10 yr of universal childhood vaccination (Nejm 2005;352:450)

Sx:

Cpox: 14-d incubation period; fever, centrifugal rash (on face and trunk 1st, then extremities)

Zoster: shingles rash; pain often, may precede and sometimes rash never appears

Si:

Cpox: fever <102°F (38.8°C); herpetic rash various ages, trunk 1st and worst. New lesions appear for 4 d

Zoster: classic herpetic lesions in dermatome distribution w hyperesthesia and pain; cranial and other neuropathies

Cpox worse w incr age, so adolescents and adults suffer more than children

Cpox:

• Anterior horn cell myelitis
• Encephalitis leading to cerebellar ataxia
• Pneumonia, esp in adults
• Group A ß-strep cellulitis and toxic shock
• Reye's syndrome (Reye's syndrome)
• Rare congenital abnormalities if infected in 1st trimester, 1/11 (Nejm 1986;314:1542)
• Embryopathy, rate is 2% if infected between weeks 8 and 20 (Nejm 1994;330:901); in pregnancy, 85% of women are immune even if don't recall having had the disease

Zoster:

• Secondary bacterial infections
• Dissemination
• Chronic postherpetic neuralgias and neuropathies (Nejm 1996;335:32); incidence incr w age, 27% at age 55 yr, 47% at 60 yr, 73% at 70 yr; as is duration, so over age 70 yr lasts >1 yr in 50%; British study found over age 69 yr w 3-mo prevalence = 20%, 12-mo preval = 10%, while under age 60 yr w 3-mo prev = 2%, 12-mo prev = <1% (Bmj 2000;321:794)
• Guillain-Barré
• Encephalitis/myelitis
• Keratitis, heals well unlike simplex
• Cerebrovasculitis presenting as TIA/CVA (Nejm 2002;347:1500) wk to mos after an episode of zoster; reversible w iv acyclovir

Lab:

Path:Skin bx or very nonspecific (HSV and VZV) Tzanck prep shows intranuclear inclusions and giant cells, enhanced by direct immunofluorescent staining assay

Serol: Antibody level to determine past immunity

Rx:

Preventive:

• Cpox: Vaccine, live attenuated (Varivax-MSD) (Med Let 1995;37:55) 0.5 cc sc × 1 for age 1-12 yr, × 2, 1-2 mo apart if age >13 yr (Mmwr 1995;44:264); must keep frozen until reconstituted, then used w/i 30 min; 100% effective, 86% in field use (Nejm 2001;344:955) vs only 45% against all disease, though 86% against mod-severe disease w significant attenuation of protection >3 yr out (Jama 2004;191:851; Nejm 2002;347:1909), or 84% effective from 95% in 1st year, though cases milder; more failures if RAD (Jama 1997;278:1495); safe (Jama 2000;284:1271); may decr later Zoster incidence (Jama 1997;278:1529; Nejm 1989;320:892; 1988;318:573). Avoid in immunocompromised and pregnant pts
• Isolation, children may return to day care or school as soon as lesions are crusted (Nejm 1991;325:1577)
• Zoster: V ZIG (varicella-zoster immune globulin) 125 U/10 kg im; expensive; use if immunosuppressed and exposed, perhaps useful in exposed healthy adult
• VZV zoster live vaccine for adults over 60 yr halves incidence and decreases postherpetic neuralgia × 66% when given at age 60 yr but diminished efficacy with age, so by 80 yr NNT for incidence is 17 and reduced neuralgia is 31 (Jama 2011;305:160, Nejm 2007;356:1338; 2005;352:2271, 2344 vs Ann IM 2006;145:317, 386)

of disease:

• Cpox:
• Acyclovir (Zovirax) 800 mg or 20 mg/kg po qid × 5 d ameliorates course modestly (Ann IM 1992;117:358; Nejm 1991;325:1539) if started in 1st 24 h but costs $32/d; or 800 mg 5×/d × 7 d (Med Let 1994;36:87) speeds healing × 2 d, costs $125
• Famciclovir (Famvir) (Med Let 1994;36:87) 500 mg po tid × 7 d, similar in all respects including cost of $130/wk
• Valcyclovir (Antiviral Antibiotics)
• Foscarnet iv q 8 h for disseminated disease in AIDS patients (Ann IM 1991;115:19)
• Zoster: Wet soaks when wet, then topical steroids when dry; antivirals may prevent postherpetic neuralgia? (no—Br Med J 1989;289:431; vs do over age 50 yr—J Fam Pract 2000;49:255; or over age 60 yr—Bmj 2000;321:794); but dual rx w steroids and acyclovir × 3 wk does speed healing and comfort? (Nejm 1994;330:896 vs Ann IM 1996;125:376)
• Famciclovir 500 mg po tid × 7 d within 3 d of rash onset speeds healing and decreases neuralgia duration (Ann IM 1995;123:89), use over age 50 yr or if severe or immunocompromised; or
• Valacyclovir (Valtrex) 1 gm po tid × 7 d (Med Let 1996;38:3); an acyclovir precursor; decr zoster neuralgia even better than acyclovir
• Acyclovir (Ann IM 1987;107:859) iv or po 10 mg/kg q 8 h for severe local, eg, eye, or disseminated, or at onset in immunocompromised host. 800 mg 5×/d × 7-10 d speeds healing and decreases acute neuralgia and neuritis (Am J Med 1988;85[2a]:84)
• Pregabalin (Lyrica) 75-150 mg bid or tid, up to 600 mg daily dose; needs renal dosing (J Am Acad Dermatol 2007;57:S136)
• Prednisone 60 mg 0 over days/weeks, if over 50 yr, esp if involves head, to speed healing along w above; no decr in neuralgia
• Amitriptyline 10-25 mg po qd × 3 mo decr postherpetic neuralgia

of zoster neuralgia (Jags 2007;55:1176; Nejm 1996;335:32) (see also Pain, Chronic, Rx):

• Desipramine 100 mg po daily
• Pregabalin (Lyrica) 75-150 mg bid or tid, up to 600 mg daily
• Gabapentin (Neurontin) (Jama 1998;280:1837) 300-1200 mg po tid
• Oxycodone or other opioid po
• Lidocaine patch 5% (Lidoderm) × 12 h qd; or gel or cream topically
• Steroid injections (Arch Neurol 1986;143:836)
• Dilantin and/or carbamazepin
• TENS
• Phenothiazines
• Nerve block, intrathecal steroid injections (Nejm 2000;343:1514) q 1 wk up to 4 in persistent debilitating disease dramatically helps >80%
• Capsaicin topical cream OTC qid 0.075% (use in diabetic neuropathy—Arch IM 1991;151:2225), questionable benefit (Med Let 1992;34:61); OTC costs $27/oz