Unit 2 - Viral Infections of the Skin Flashcards
what are causes of non-infectious rashes?
- allergies
- cancer
- injury
- autoimmune
what are causes of infectious rashes? what must you then ask?
- bacterial
- fungal
- protozoan
- viral
must ask if this is treatable, and if not what the prognosis is
ranked from most to least common, what are viral causes of rashes?
- Herpesvirus
- Coxsackie virus
- Human papilloma virus
- Poxvirus
- Measles
- Rubella
ranked from most to least common, what are herpes viral causes of rashes?
- herpes simplex virus type 1 and 2
- varicella zoster virus
- Epstein-Barr virus
- Cytomegalovirus
- Roseola virus
- Kaposi’s sarcoma herpesvirus
ranked from most to least common, what are poxviral causes of rashes?
- Molluscum contagiosum virus
- Monkeypox virus
- Variola virus
- Vaccinia virus
what are exogenous sources of viral skin infections?
from outside
- infection at site of a lesion
- breaks in skin integrity (cuts, insect bites, pimples, etc.)
- mucous membranes
what are endogenous sources of viral skin infections?
from within (disseminated infection)
- viremia: spread through blood, lymph, or nervous system
- reactivation from latency (herpesvirus reactivate from neurons or lymphocytes)
how are rashes categorized?
by color, contents, and shape
what is the definition of dermatitis?
inflammation of the skin, non-infectious
what is the definition of exanthem?
an eruptive disease, infectious rash
what is the definition of macular/macule?
flat, discolored patch
what is the definition of vesicular/vesicle?
raised, fluid-filled blister
what is the definition of papular/papule?
raised, discolored rash
what is the definition of erythema(tous)?
redness
what is the definition of petechial/petechiae?
tiny dark spots due to localized hemorrhage
what is the definition of pruritis/pruritic?
itchy
what is the definition of pustular/pustule?
vesicle filled with pus
what is the definition of umbilicated?
pustule with dimple (umbilicus) in center
herpesvirus
- structure
- primary infection
- latency
- recurrence
large, enveloped DNA virus (8 different species)
- primary infection is first exposure and disease
- latency in neurons or lymphocytes
- recurrence with or without symptoms
- most people are infected with >3 kinds
connection between primary and recurrent herpesvirus infections
- exposure/transmission via secretions in membranes
- primary disease (first infection) in children; severe to mild
- latency (in neurons or lymphocytes, with asymptomatic shedding)
- reactivation (recurrent disease in adults, often to never)
how can herpesvirus be transmitted?
secretions (saliva, breastmilk) and mucous membranes (oral, genital)
-can be from infected person with primary infection, or recurrence of latent infection
when can asymptomatic shedding occur?
at any time, even during latency and recurrence
-this can transmit to naive person
describe primary herpes simplex virus type 1 clinically? how it’s spread?
stomatitis
- usually occurs in childhood (50-80% of population is seropositive)
- spread by close contact with active lesions or asymptomatic shedding
- lesions on mouth, face, nose, eyes, etc.
- latency in dorsal root ganglia neurons
- HSV-1 infections are usually above the waist, but can be genital
treatment of HSV-1? recurrent HSV-1?
primary: oral acyclovir, zovirax or derivatives
recurrent: acyclovir, zovirax, valtrex, famvir
- use as needed for outbreaks or prophylaxis to prevent recurrences
describe recurrent HSV-1? causes?
herpes labialis (cold sores)
- 20% of seropositive people have recurrent lesions on lips, eyes, or inside mouth
- recurrence triggered by fever, UV exposure, hormones, stress, physical trauma
- lesions are contagious; secretions can spread virus without symptoms
what is HSV keratitis and corneal scarring?
primary infection of the eye occuring at birth from vaginal mucosa
- caused by HSV-1/2 recurrence
- chronic HSV keratitis can cause corneal scarring and vision loss
- disease is mediated by infiltration of T-cells that destroy the cornea
treatment of HSV keratitis/corneal scarring?
antivirals are important to prevent corneal transplant
-corneal transplant may be needed if damaged too much
describe herpetic whitlow?
primary HSV-1/2 of non-mucosal sites, acquired by direct contact (such as putting bare hands in other’s mouths)
- susceptible: dentists, hospital workers (decreased from glove use), wrestlers
- recurrences at unusual sites: hands, legs, back
what is treatment and prevention for herpetic whitlow?
treat: acyclovir and derivatives
prevent: gloves
explain primary genital herpes (HSV-2)
extensive vesicular, pustular, or erythematous lesions on penis, labia, anus (oral/ocular possible)
- pain, itching, fever, malaise, headache
- -usually but not always below waist
what is treatment for primary HSV-2? recurrent?
primary: antiviral treatment important to shorten acute infection, prevent spread to brain
recurrent: prophylactic antiviral treatment can reduce recurrence and thus transmission
can you have HSV-1 and HSV-2?
yes, double infections are very common
what has the highest risk for congenital infections (mother to fetus)?
HSV-2 primary genital herpes
-recurrent genital herpes has moderate risk for perinatal infection
explain HSV-2 recurrent genital herpes?
prodrome: itching, tingling at lesion site a day before outbreak
- vesicular lesions appear on labia, penis, anus, mouth, etc.
- lesions are contagious, but shedding and transmission CAN OCCUR WITHOUT SYMPTOMS
- frequency of recurrences is highly individual; ranges from never to monthly
explain primary varicella-zoster virus?
chicken pox
- aerosol transmission is highly contagious
- 1-2 week incubation period (contagiousness, fever, malaise precede rash)
- latency in dorsal root ganglia neurons
- severity increases with age
what is the only herpes virus transmittable through the air?
chickenpox; primary varicella-zoster virus
how is the chicken pox rash distinctive?
“dew drops on rose petals”
- few to hundreds on face/trunk
- lesions are itchy, vesicular, and form scabs that may scar
what is treatment, prevention, and complications of chicken pox?
prevent: Varivax vaccine
treat: acyclovir, Foscarnet
complications: visceral infection, dissemination to brain, pneumonitis, bacterial infection of lesions
what is shingles?
recurrence of VZV
- prodrome: burning, itching, tingling
- outbreak occurs along a single dermatome
- vesicular lesions are extremely painful, pruritic
- more common in elderly and immunocompromised
what is treatment and complications of shingles?
treat: acyclovir and derivatives
complication: keratitis, retinitis, Bell’s palsy, postherpetic neuralgia
what is herpes zoster ophthalmicus? treatment?
HZO; approximately 30% of zoster outbreaks affect the face
- zoster in the eye can destroy retina, rapidly leading to blindness
- all tissues of eye can be infected and damaged
- long-lasting pain is common
- aggressive treatment
explain VZV vaccines?
live, attenuated virus (Oka/Merck strain)
- Varivax to prevent varicella (ages 1-60 is 80-90% effective)
- Zostavax to prevent zoster (ages >50 is 50% effective)
- -at 14x higher dose than Varivax
- ACIP recommends getting both
what is oral hairy leukoplakia?
EBV recurrence causing epithelial overgrowth on tongue
- nonpainful hairy of reathery lesions on tongue or buccal mucosa
- associated with HIV infection, transplantation, chemotherapy, etc.
explain cytomegalovirus primary infection?
primary CMV infection is usually asymptomatic and acquired in childhood
- very similar to infectious mononucleosis from EBV)
- differentiate b/c CMV has petechial rash and jaundice, while EBV has sore throat
what is exanthem subitum? transmission? clinical signs?
roseola caused by HHV6b/7 (no known disease linked to HHV6a)
- HHV infects CD4+ T-cells, site of latency
- transmitted by saliva
- by age 2, >90% of children have had roseola twice
- has 3-day illness of high fever, followed by faint rash on trunk
why is roseola sometimes misdiagnosed?
many infants mistakenly given antibiotics for suspected infection
-since the rash comes after the third day, it’s attributed to a drug allergy instead of roseola
explain Kaposi’s sarcoma herpesvirus primary infection
no known disease
- prevalent in African, Mediterranean, homosexual populations
- evidence of sexual transmission
- found in B-cells and endothelial cells (probable site of latency)
what is linked to HHV8/KSHV?
- Kaposi’s sarcoma
- body cavity-based lymphomas
- Castleman’s disease
- hyperplastic lymphadenopathy
what is Coxsackie virus virology? the types of clinical effects?
large family of small, naked, ssRNA viruses (Enteroviridae –> poliovirus, others that cause GI infections, neuromuscular disease, encephalitis, meningitis)
-skin manifestations and hand, foot, and mouth disease
skin manifestations of Coxsackie virus?
- herpangina - throat infection causes red-ringed blisters and ulcers on tonsils and soft palate
- hemorrhagic conjunctivitis - begins as eye pain, then red, watery eyes with swelling, light sensitivity, and blurred vision
what is hand, foot, and mouth disease caused by? clinically?
from Coxsackie virus
- painful red blisters on the throat, tongue, gums, hard palate, inside of cheeks, and palms/soles
- feels like something is pricking you
- common in pre-school children and parents
how is hand, foot, and mouth disease transmitted? treatment? prevention?
highly contagious
- spread on hands and surfaces contaminated by feces and saliva
- aerosol spread from sneezes or coughs
- treatment: none (passes due to immune system, not clearance of virus)
- prevention: handwashing and sanitation
virology of HPV? how is it spread? clinically?
small, naked DNA virus
- infects skin, genitals, cervix, anus, mucosa
- -warts are raised and without any redness around them (not inflammed)
- spread by direct contact
HPV treatment? prevention?
- treat with chemical or surgical removal
- prevent with Gardasil (vaccine for young women, now for boys age 11)
what must you be careful to differentiate HPV warts from?
molluscum contagiosum virus
what are poxvirus famous for?
skin rashes
-worst and now almost extinct human poxvirus infection
what is molluscum contagiosum virus? what do they look like?
MCV poxvirus (large, envoloped DNA virus)
- lesions are pearly, flesh-colored, raised, and umbilicated
- -occur anywhere on body in children
- -anogenital area in sexually active adults
- -occasionally, a single “giant molluscum” nodule may occur (10 mm)
- -lesions rarely appear on palms, soles, mucosa, face, or eyes
transmission and incidence of MCV?
transmit by skin-skin contact or by fomites (tattooing, wrestling, towels)
- disease incidence is 2-8%
- -most common in school-age children
- -much higher incidence in HIV+ poopulation (5-20%)
treatment of MCV and HPV?
surgery, cryotherapy, or chemicals
-topical treatment with Cidofovir is promising for MCV only, although somewhat toxic
explain the variola virus
- clinical signs?
- stages?
smallpox; fever, severe aching pains and prostration
- 2-3 days later, umbilicated papular rash over the face and extremities
- rash stages: papular –> vesicular –> pustular –> scabs (leave pitted scars)
- death usually during second week from overwhelming infection
treatment of smallpox?
supportive care and vaccination
- originally vaccinated via vaccinia virus (cowpox)
- -variola virus and other poxviruses were “blended” to create modern vaccine strain vaccinia virus
is vaccinia perfectly safe?
no, there can be adverse vaccination reactions
-vaccinia is a live vaccine that carries risk for some people, including immunocompromised
auto-inoculation of vaccinia?
from arm to eyes
generalized vaccinia?
virus disseminates through body
eczema vaccinatum?
contraindicated in anyone with eczema
progressive vaccinia?
-treatment?
vaccinia necrosum or gangrenosum
- occurs in immunocompromised patients
- treatment includes Cidofovir and VIG (vaccine immune globulin)
virology of measles? symptoms?
paramyxovirus, enveloped, negative strand RNA
- contagious during incubation period
- symptoms: cough, conjunctivitis, fever, rash, Koplik’s spots
what are Koplik’s spots?
small, red spots with bluish centers on buccal mucosa
-in measles
virology of Rubella? symptoms?
German measles
- togavirus, enveloped, +RNA
- respiratory virus, aerosol spread
- maculopapular rash, lymphadenopathy, arthralgia
- congenital infections severe
treatment of Rubella? prevention?
treatment: none
prevention: MMR vaccine; herd immunity is crucial
