Herpes Flashcards
What is herpes?
dsDNA virus with eight virus; 3 subfamilies: alpha, beta, gamma
What is the alpha herpes family?
HSV-1, HSV-2 and VZV
What is the beta herpes family?
CMV, roseola
What is the gamma herpes family?
EBV and Kaposi’s sarcoma
What are the layers of herpes?
episomal DNA genome, capsid, tegument, envelope
What is the capsid?
surrounds the center of the virus, encases dsDNA genome, connection between viral capsid and host envelope allows herpes virus to enter host’s cytoplasm
Where does viral replication take place?
in the host cell’s inner nuclear membrane of the nucleus
What is the tegument?
dense protein layer surrounding the capsid, creates link between capsid and the host cell’s lipid bilayer envelope
What enzyme is used in herpes replication?
virus uses host’s DNA polymerase (the DNA populating mechanism) and reverse transcriptase to transcribe and produce viral proteins
What is the leading cause of infectious corneal blindness in developed countries?
HSV-1; 1.5 million cases a year globally (40,000 cause severe monocular VA loss)
How is herpes simplex categorized?
by viral strand (1 or 2) and infection (primary or recurrent)
What is HSV-2?
genital herpes, mostly associated with sexual transmission or neonatal infection; can involve any mucosal membrane
How is primary HSV-1 transmitted?
mucosal membranes, saliva, tears; highly contagious
What is the incidence of primary HSV-1?
60% of population by age 5 and 100% by age 60
Where are most primary HSV-1 signs located?
oropharynx>ocular
Who gets primary HSV-1?
school-aged children>neonates and a severe presentation in neonates and immunocompromised
What symptoms are there for primary HSV-1?
symptoms are rare; 94% asymptomatic; flu like malaise, low-grade fever, concurrent upper respiratory infection
What are clinical signs of primary HSV-1?
pre-auricular node swelling unilaterally, vesicular rash (eyelids and adnexa), follicular conjunctivitis, corneal punctate lesions rare but can coalesce into epithelial dendrite, labial vesicular eruptions aka cold sores, gingivostomatitis
Where is the herpes virus present in the oropharynx?
stratified squamous epithelium of oral mucosa
T/F dendritic ulceration for primary HSV-1 is limited to the epithelium and cannot involve the stroma
true
What is the transmission of primary HSV-1?
primary HSV 1 transmission to active infection to latency in trigeminal and dorsal root ganglion to reactivation and recurrent HSV-1
What is latency?
via retrograde transport, infected epithelial cells –> trigeminal and dorsal root ganglia, inactive
What is reactivation?
via anterograde transport, trigeminal and dorsal root ganglion –> epidermis, reactivated
Can recurrent HSV-1 become latent?
yes, establishes latency after active infection and can become reactivated
What are triggers for HSV recurrence (old theory)?
stress, UV light, menstruation, illness, surgery/iatrogenic, toxic
How is recurrent HSV-1 transmitted?
mucosal membranes, saliva, tears
What is the predilection for recurrent HSV-1?
male, no correlation to race or age
Who has the most severe recurrent HSV-1 presentation?
children and immunocompromised
Is recurrent HSV-1 unilateral or bilateral?
unilateral»_space;> bilateral
What are symptoms of recurrent HSV-1 (HSK)?
pain/ocular discomfort, photophobia, watering, itching, FBS, decreased vision/blurry vision, corneal desensitization
What are signs of recurrent HSV-1 (HSK)?
pre-auricular node swelling, vesicular rash, follicular conjunctivitis, dense coalesced punctate keratitis, dendritic keratitis (72% occurrence), adnexal vesicles
T/F any insult to the cornea can cause lid edema?
true
What are types of HSK?
epithelial, stromal, necrotizing
What is epithelial HSK?
dendritic, geographic, neurotrophic, marginal
What is stromal HSK?
disciform, immune
What is necrotizing HSK?
aka interstitial endotheliitis
Describe neurotrophic keratitis
rapid progression, creates false sense of improvement/asymptomatic, round/oval shaped, smooth borders, stain completely with fluorescein
What is marginal/limbal epithelial HSK?
immune response to viral cells, (+) limbal neo, (-) stain