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Toronto Notes 2019 Infections
Viral Infections
HERPES SIMPLEX
Clinical Presentation
• herpetiform(i.e.grouped)vesiclesonanerythematousbaseonskinormucousmembranes • transmittedviacontactwitheruptedvesiclesorviaasymptomaticviralshedding
• primary
■ children and young adults
■ usually asymptomatic; may have high fever, regional lymphadenopathy, malaise
■ followed by antibody formation and latency of virus in dorsal nerve root ganglion
• secondary
■ recurrent form seen in adults; much more common than primary
■ prodrome: tingling, pruritus, pain
■ triggers for recurrence: fever, excess sun exposure, physical trauma, menstruation, emotional stress,
URTI
• complications:dendriticcornealulcer,EM,herpessimplexencephalitis(infantsatrisk),HSVinfection
on AD causing Kaposi’s varicelliform eruption (eczema herpeticum)
• twobiologicallyandimmunologicallydifferentsubtypes:HSV-1andHSV-2
■ HSV-1
◆ typically “cold sores” (grouped vesicles at the mucocutaneous junction which quickly burst)
◆ recurrent on face, lips, and hard palate, but NOT on soft, non-keratinized mucous membranes
(unlike aphthous ulcers) ■ HSV-2
◆ usually sexually transmitted; incubation 2-20 d
◆ gingivostomatitis: entire buccal mucosa involved with erythema and edema of gingiva ◆ vulvovaginitis: edematous, erythematous, extremely tender, profuse vaginal discharge ◆ urethritis: watery discharge in males
◆ recurrent on vulva, vagina, penis for 5-7 d
◆ differential diagnosis of genital ulcers: Candida balanitis, chancroid, syphilitic chancres
Investigations
• TzancksmearwithGiemsastainshowsmultinucleatedgiantepithelialcells
• viralculture,electronmicroscopy,anddirectfluorescenceantibodytestofspecimentakenfromthe
base of a relatively new lesion
• serologictestingforantibodyforcurrentorpastinfectionifnecessary
Management
• HSV-1
■ treat during prodrome to prevent vesicle formation
■ topical antiviral (Zovirax®/Xerese®) cream, apply 5-6x/d x 4-7 d for facial/genital lesions
■ oral antivirals (e.g. acyclovir, famciclovir, valacyclovir) are far more effective and have an easier
dosing schedule than topicals • HSV-2
■ rupture vesicle with sterile needle if you wish to culture it
■ wet dressing with aluminum subacetate solution, Burow’s compression, or betadine solution ■ 1st episode: acyclovir 200 mg PO 5x/d x 10 d
◆ maintenance: acyclovir 400 mg PO bid
■ famciclovir and valacyclovir may be substituted and have better enteric absorption and less frequent
dosing
■ in case of herpes genitalis, look for and treat any other STIs ■ for active lesions in pregnancy, see Obstetrics, OB30
HERPES ZOSTER (SHINGLES)
Clinical Presentation
• unilateraldermatomaleruptionoccurring3-5dafterpainandparesthesiaofthatdermatome • vesicles,bullae,andpustulesonanerythematous,edematousbase
• lesionsmaybecomeeroded/ulceratedandlastdaystoweeks
• paincanbepre-herpetic,synchronouswithrash,orpost-herpetic
• severepost-herpeticneuralgiaoftenoccursinelderly
• Hutchinson’ssign:shinglesonthetipofthenosesignifiesocularinvolvement
■ shingles in this area involves the nasociliary branch of the ophthalmic branch of the trigeminal nerve (V1)
• distribution:thoracic(50%),trigeminal(10-20%),cervical(10-20%);disseminatedinHIV
Etiology
• causedbyreactivationofVZV
• riskfactors:immunosuppression,oldage,occasionallyassociatedwithhematologicmalignancy
Dermatology D29
Both HSV-1 and HSV-2 can occur on face or genitalia
Erythema Multiforme
Etiology: most often HSV or mycoplasma pneumoniae, rarely drugs
Morphology: macules/papules with central vesicles; classic bull’s-eye pattern of concentric light and dark rings (typical target lesions)
Management: symptomatic treatment (oral antihistamines, oral antacids); corticosteroids in severely ill (controversial); prophylactic oral acyclovir for 6-12 mo for HSV-associated EM with frequent recurrences
Herpes zoster typically involves a single dermatome; lesions rarely cross the midline