Download Viral Dermatoses Xiao Sheng

Viral Dermatoses
Department of Dermatology
Xiao Sheng-Xiang
General Description
• Definition
Viral dermatoses are the cutaneous
diseases resulting from viral infections.
Classification of Viral dermatoses
• Herpesvirus group
– Herpes simplesx
– Varicella ( Chickenpox )
– Herpes Zoster
– Roseala Infantum ( Sixth disease)
– Kaposi’s sarcoma
Classification of Viral dermatoses
• Poxvirus group
Molluscum contagiosum, milker’s nodules
• Papovavirus group
Warts(common warts, Flat warts,
plantar warts, genital warts)
Classification of Viral dermatoses
• Parvovirus
Erythema infectiosum( fifth disease)
(B19 virus)
• Paramyxovirus group
Measles, rubella
Classification of Viral dermatoses
• Picornavirus group (enteroviruses)
Hand-fooot –mouth disease (coxackie
virus)
• Retroviruses
AIDS
Herpes Simplex
Etiology
• Herpes Simplex Virus ( HSV ): DNA
Virus
– Two antigenic types: HSV-1, HSV-2
HSV-1: lesions on the lips, face
HSV-2: genital herpes
Lesions anywhere may be caused by either
antigenic type.
– Transmission: Intimate contact ( direct
inoculation through traumatized skin )
– Primary infection and recurrent infection
Primary infection: first infection
After primary infection
virus migrates to the
neuronal cells in ganglion
latent infection
latent virus to reactivate by triggering factors
virus particles move on the nerve
in the epithelial cells
replicate
recurrent infection
– Triggering factors: fever, trauma, emotional
stress, menstruation
Epidemiology
• 85% of adults worldwide are seropositire for HSV-1.
Seroprevalence for HSV-2 is lower, appear at the age
of onset of sexual activity.
USA: ~23% of adults are infected with HSV-2
Developing countries: 60~95% of infection rates of
HSV-2
• Incubative or subclinical infection: 90% of all infected
Clinial manifestation
• Features of the lesion: multiple small
papules, vesicles, clusted together.
Mature lesion: grouped vesicles and / or pustules
on an erythematous edematous base
• Common site for lesions: face, lips, mouth,
neck, anogenital area
• Heal within 1-2 weeks
Diagnosis
• Clinical Diagnosis
• Laboratory Test
Tzanck smear: take a smear of cells from the base
of the skin lesion
spread the cells on a glass
slide
stain with wright or Giemsa Stain
look
for multinucleated giant cells
Non specific: HSV VZV
Accuracy rate: 60~90%
False positive rate: 3~12%
• Detection of virus antigen of the lesion
Materials:vesicular fluid ,cells from the base
of skin lesion
Methods: direct fluorescent antibody test
immunoperoxidase tchniques
• Virus culture
Emphasis
•
Serologic tests (detection of anti-HSV
antibody of the blood) are generally not
used in determining whether a skin lesion
is due to HSV infection.
•
A positive result to a serologic test
indicates only that the individual is
infected with that virus, not that the viral
infection is the cause of the current lesion.
Threatment
• Therapeutic principle
To shorten disease duration
To prevent bacterial infection
To prevent recurrence
Threatment
• Anti-HSV therapy
Primary infection:
Acyclovir: 0.2g, five times/day×7-10days
Valaciclovir: 0.3g, bid ×7-10days
Famcyclovir: 0.25g, tid ×7-10days
Recurrent infection: treatment duration 5 days
Threatment
• Severe recurrent cases
acyclovir
valacyclovir
04g bid
0.3g qid
famcyclovir 0.25g bid
4M to 1Y
Threatment
Other antiviral agents like IFN- or
applied
–
Topical therapy
1% pencyclonir cream,
1% acyclovir cream,
topical antibiotics
may be
Varicella & herpes zoster
Etiology
Varicela-zoster virus (VZV):
human herpes virus-type 3
Tranmmission:
direct contact
respiratory route
A very communicable disease
Primary infection:
varicella or subclinical infection
Virus reactivation:
herpes zoster
Cellular immunity and herpes zoster
90% cases of varicela ＜10 years of age
Clinical manifestation
• Varicella
– Skin lesion: macules →vesicles (within
24hs) →successive fresh vesicles
(within 4 days)
– Hemorrhagic, necrotic or bullous lesion
The site of lesions:
trunck, face, oral mucosa
Other symptoms:
fever (moderate )
pruritus, secondary infection
• Herpes zoster
– Features of the lesions:
Occurs unilateraly within the distribution of a cranial
or spinal sensory nerve
Skin lesions: papules, plaques of erythema, blisters
in the dermatome
– Pain associated with herpes zoster
– Disease duration: 2-3weeks in the younger,
6 weeks or more in the elderly
Diagnosis , differential diagnosis
• Herpes zoster and herpes simplex
In the early stages of herpes zoster, if the
number of lesions of zoster is limited, it can
be relatively indistinguishable from herpes
simplex.
Herpes zoster: more painfull, progress to
involve more area over 24hs
Treatment
• Varicella
Antiviral therapy
acyclovir 20mg/kg/d ×5days ,not
routinly recommended
• Topical antipruritic lotions
Herpes Zoster
• General therapy
– Restrict physical activities
– Local applications of heat
– Topical anesthetics, antipruritic lotion, topical
antiviral agents
– Vesicular stage: cool compress
• Antiviral therapy: reduce the duration of
pain
– Start preferably within the first 3 or 4 days
– Severe cases: intravenous therapy (acyclovir,
5mg/kg, tid)
• Refrence doses
– Acyclovir 0.8g 5times/day ×7 days
– Valaciclovir 1.0g tid ×7 days
– Famciclovir 0.5g tid ×7 days
• Zoster associated pain
– Drug therapy:
simple analgesics like aspirin
Tricyclic antidepresants like amitriptyline
anticonvulsants like carbamarepine
– Local anesthetics: 10% lidocain gel or patches
– Nerve blocks
Bacterial Dermatoses
Impetigo
Etiology
• 50~70% of cases: staphylococcus aurens
• The reminder: streptococcus or a
combination
• Occur frequently in children in hot, humid
weather
• Sources of infection for children: pets, dirty
fingernails, crowded housing areas
Clinical manifestation
• Nonbullous impetigo
Begins with 2-mm erythematous macules
vesicles or bullae
discharge
seropurulent
golden yellow crusts
spread by scratching and autoinoculation
• Bullous impetigo
occurs in new-born infants (4th-5th day of
life)
bullae in the face, hand and other sites
later weakness, fever or subnormal
temperature
Diarrhea
Bacteremia, pneumonia or meningitis
Diagnosis
• Clinical diagnosis
• Bacterial examination: gram stain or
culture
Treatment
• Topical agents
Rivanol ( Compound Ethacridine Solution)
2% mupirocin ointment
other topical antibiotic agents
Systemic agents
• Antibiotics
– Semisynthetic penicillin (penicillinaseresistant) like dicioxacillin
– Cephalosporin
– Erythromycine, azithromycine
– Clindamycine
Staphylococcal scalded skin syndrome
(SSSS)
A generalized, confluent, superficially
exfoliative bacterial disease, occurring in
neonated and children
Etiology
• Group 2 staphylococcus aureus, most
commonly phage type 71
• Epidermolytic exotoxin
• Infection sites: pharynx, nose, ear,
conjunctive, septicemia, cutaneous
infection
Clinical manifestations
• Abrupt fever
• Skin tenderness
• Diffuse erythema in the neck, groin, axillae
• Generalized exfoliation within hours to
days, sheets of epidermis separating
• Positive nikolsky sign
• Healing within 10 days
Diagnosis
• Laboratory findings
– Leukocyte count,neutrophil proportion
– Bacterial culture: mucous membranes ,
skin
Treatment
• Antibiotics
• Fluid therapy and general supporative
measures