viral infections of skin Flashcards
what are the viral skin manifestations listed in order from most common to least?
Herpesviruses, coxsackie virus, HPV, poxviruses, measles and rubella
what are the sources of viral skin infections?
exogenous (from the environment) or endogeneous (from disseminated infection)
how do viruses infect the skin?
through breaks in skin integrity or mucous membranes
what are the endogenous causes of viral skin infection?
viremia or reactivation from latency
define dermatitis.
inflammation of the skin
what is exanthem?
an eruptive disease (infectious rash)
define macular, papular and vesicular.
macular is a flat discoloration, papular is a raised patch, vesicular is a raised, fluid filled blister
define erythema and petechiae
erythema is redness. petechiae are tiny dark spots due to localized hemorrhage
what is pruritis?
itching
what is a pustule? what does umbilicated mean?
a vesicle filled with pus. it is umbilicated if it has a dimple in the center
what type of virus are herpesviruses? how common are they?
large enveloped DNA viruses. most people are infected with greater than three kinds
how are herpesviruses transmitted?
by secretions and mucous membranes of an infected individual with primary or recurrence of a latent infection. asymptomatic shedding also occurs
where do herpesviruses establish latency?
in neurons or lymphocytes during primary infection
describe primary HSV 1. who does it infect?
usually in childhood. lesions on mouth and face (usually above the waist)
where does HSV 1 latency occur? how is it treated and how common is it?
in dorsal root ganglia
treat with oral acyclovir
50-80% of population is infected
what are some common names of recurrent HSV1? what percentage of people have recurrence
cold sores, canker sores or fever blisters
20% of people have recurrent lesions
what triggers HSV 1 recurrence? what is the treatment?
fever, UV exposure, hormones, stress and physical trauma
treat with acyclovir, zovirax, valtrex and famvir as needed or prophylactically
which herpesviruses cause keratitis and corneal scarring? when does primary infection occur? what causes the damage?
HSV 1 and 2
primary infection occurs at birth from vaginal mucosa
caused by infiltration of T cells into the cornea
what is herpetic whitlow? how is it treated?
primary HSV 1 or 2 on nonmucosal sites. risk factor is putting bare hands into people’s mouths. treat with acyclovir
describe primary HSV 2 lesions.
extensive vesicular, pustular and erythematous lesions on penis, labia, anus and possibly oral areas. accompanied by itching, fever malaise and headache
why is antiviral treatment important for primary HSV 2 lesions?
to shorten the acute infection and prevent spread to the brain (meningial involvement indicated by malaise and headache)
describe recurrent HSV2 lesions. why is treatment important?
prodrome accompanied by vesicular lesions. frequency is variable and prophylactic antiviral can reduce recurrences and transmission.
what is the risk for perinatal and congenital infection with HSV2?
most risk during primary infection congenitally. moderate risk for perinatal infection with recurrence
what is the primary infection of vericella zoster virus? where is it latent and what is the recurrence?
chicken pox
latent in dorsal root gangial neurons and recurrs as shingles
how is varicella transmitted? describe the rash and symptoms
aerosol transmission
fever and malaise precede and accompany rash of dew drops on rose petals on face and trunk (itchy)
what are the complications of varicella?
visceral infection, dissemination to the brain, penumonitis and bacterial infection of lesions (increases in severity with age of primary infection)
how is varicella treated?
prevented with varivax (vaccine) and treated with acyclovir and foscarnet
describe herpes zoster.
prodrome followed by outbreak of vesicular, painful lesions on a single dermitome. more common in elderly and immunocompromised
how is zoster treated? what are the possible complications?
acyclovir
keratitis, retinitis, bells palsy and postherpetic neuralgia
what is herpes zoster opthalmicus? which tissue are effected? how is it treated?
shingles in the eye that can destroy the retina. effects all tissues of the eye and long lasting pain is common. treat aggressively with acyclovir and IV foscarnet
describe the VZV vaccines. what kinds are there and at what doses?
live attenuated virus
varivax- prevent varicella (80-90% effective)
zostavax prevents zoster (give >50, 50% effective)
zostavas has 14 times higher dose than varivax
what illness does epstein barr virus cause? who does it infect? what cells?
causes mononucleosis, infects most people in childhood. infects the B cells and the epithelia of the oropharynx
where is EBV latent? what recurrences does it cause?
latent in the B cells. recurrences are linked to B cell cancers especially in the immunocompromised. (oral hairy leukoplakia)
who does cytomegalovirus infect? what are the symptoms?
infects children with mononucleosis similar to EBV. There is no sore throat and there is a petechial rash and jaundice
what viruses cause roseola? what cells does it infect?
HHV6b and HHV7
infects CD4 T cells (also site of latency)
how is roseola transmitted? what are the symptoms? how is it often treated?
saliva
three day high fever followed by a faint rash on the trunk
children given antibiotics mistakenly and the rash is presumed to be an allergy to the antibiotic
what virus causes kaposis sarcoma? where is it prevalent and what cells does it infect?
HHV8
prevalent in Africa, the mediterranean population
infects B cells and endothelial cells (site of latency)
what other cancers are associated with HHV8?
body cavity based lymphomas and castleman’s disease (hyperplastic lymphadenopathy)
what is the morphology of coxsackie virus?
small, naked ssRNA virus of the enterovirus family
what are the skin manifestations of coxsackie virus?
herpangina- throat infection with red ringed blisters and ulcers on the tonsils and soft palate
hemorrhagic conjunctivitis- eye pain with red, watery eyes, light sensitivity and blurred vision
what is hand, foot and mouth disease?
presentation of coxsackie virus with painful blisters in the mouth, on the palms and soles of the feet. common in preschool aged children and their parents
how is coxsackie spread? how is it treated?
spread on hands and surfaces contaminated by feces and saliva. also aerosolized
no treatment
what is the morphology of HPV and where does it infect?
small, naked DNA virus
infects skin, genitals, cervix, anus and mucosa
how is HPV spread? how is it treated?
spread with direct contact
treat with chemical or surgical removal
prevent with gardasil
what are the three pox viruses? why are they becoming more of a problem?
molluscum contagasiosum, monkey pox and smallpox
more of a problem because the smallpox vaccine is no longer being given which protected against monkey pox
describe the appearance of molluscum contagiosum virus. where do they appear?
pearly appearing vesicle that is umbilicated without inflammation. found anywhere on the body (except face, mucosa, palms and soles) in children and on anogenital area in sexually active adults
who is commonly affected by molluscum contagiosum virus?
school aged children and HIV positive population
how is molluscum contagiosum virus treated?
with cidofovir. remove with surgery, cryotherapy or chemicals (recurs if “popped”)
where does monkey pox occur and how is it transmitted?
in west and central africa
squirrels are the natural host and it also infects monkeys. transmitted through contact, aerosol, ingestion, needles or person to person
what virus causes smallpox? what are the symptoms?
variola virus
fever, severe aching pains and prostration. umbilicated papular rash over face and extremities. death in second week
how is smallpox treated?
supportive care and vaccination. eradicated from the wild with worldwide vaccination
what virus is included in the smallpox vaccine?
vaccinia virus- mixture of variola and other poxviruses. live attenuated vaccine
what are the possible complications from smallpox vaccine?
autoinnoculation of the eyes, generalized dissemination in the body, eczema vaccinatum (contraindicated for people with eczema), and progressive vaccinia (necrosis and gangrene in immunocompromised patients) all are recoverable except the last
what is the morphology of measles virus? why does it spread so easily?
paramyxovirus enveloped with negative strand RNA
infectious during the incubation period
what are the symptoms of measles virus?
cough, conjunctivitis, fever and rash (small red spots with bluish centers in mouth called koplik’s spots)
what is the morphology of rubella virus?
togavirus, enveloped with positive strand RNA
how is rubella sperad? what are the symptoms?
aerosol spread
maculopapular rash, lymphadenopathy and arthralgia (worse if congenital)
