Microbiology of Viral Skin Infections Flashcards
(51 cards)
What are chickenpox and shingles both caused by?
Varicella zoster virus:
Chickenpox is Varicella
Shingles is Zoster
Describe chickenpox virus
Primary infection is normally in childhood with a generalised rash and fever
Virus establishes latency
Describe shingles
Reactivation of varicella zoster virus typically occurs in old age and in immunocompromised patients
Follows a dermatomal pattern
Symptoms and progression of chickenpox?
Macules to papules to vesicles to scabs to recovery; the lesions are centripetal and the density varies. Skin is very inflamed
Fever
Itch
Complications of chickenpox?
Secondary bacterial infection
Pneumonitis
Haemorrhagic rash (purpuric confluent lesions)
Scarring
Encephalitis
Predictors of severity of chickenpox?
Extremes of age
Depressed cell-mediated immunity
How does neonatal chickenpox (VZV) occur?
Secondary to chickenpox in the mother, in late pregnancy; this has a higher mortality
Prevention of neonatal VZV?
Varicella Zoster immune globulin in susceptible women
Progression of shingles?
Tingling/pain to erythema to vesicles to crusts
Describe shingles zoster assoc. pain?
Neuralgic in character
What is post-herpetic neuralgia?
When the pain persists beyond 4 weeks, this is what it is called; part. occurs in the elderly and in those with trigeminal distribution zoster
Scarring in shingles?
Not common
Different distributions of shingles?
Ophthalmic zoster - reactivation of dormant VZV residing within the ophthalmic nerve (of the trigeminal nerve) and requires an urgent ophthalmic referral
Maxillary division of trigeminal nerve (around left cheek and side of the nose)
Mandibular division of the trigeminal nerve (affects right side of the face, from the temple to the chin)
When does ophthalmic zoster occur?
Can happen in children, esp. if chickenpox is in utero or if they become immunocompromised
What is Ramsay-Hunt syndrome?
AKA herpes zoster otticus OR geniculate ganglion - caused by reactivation of VZV in the geniculate ganglion
Leads to vesicles and pain in the auditory canal and throat
Symptoms of Ramsay-Hunt syndrome?
Facial palsy (7th nerve palsy) - poorer prognosis than Bell’s palsy (idiopathic 7th nerve palsy - both are caused by VZV but Ramsay-Hunt Syndrome has a poorer prognosis and is accompanied by the following symptoms)
Irritation of the vestibulocochlear (8th) cranial nerve:
Deafness
Vertigo
Tinnitus
Why is the VZV chickenpox vaccine used for shingles?
Can be used in high titre in the elderly to reduce impact of shingles:
Reduces incidence of shingles by 38% and post-herpetic neuralgia by 67%
What is primary gingivostomatitis?
Combo of stomatitis and gingivitis; this is often the initial presentation of the first/primary herpes simplex viral infection (tends to occur in pre-school children)
Symptoms of primary gingivostomatitis?
Extensive ulceration in and around the mouth that last around a week
What happens when Herpes Simplex Virus recurs?
Blistering rash at the vermillion border that can spread to the finger (herpetic whitlow) or eczema herpeticum (can be life-threatening)
Difference between HSV type 1 and 2?
HSV Type 1:
Main cause of oral lesions and causes half of genital herpes; also causes encephalitis
HSV Type 2:
Rare cause of oral lesions but causes half of genital herpes; also causes encephalitis/disseminated infection (part. in neonates)
VZV and HSV therapy?
Aciclovir is an analogue of guanosine that is incorporated into viral DNA, inhibiting replication
This is an effective and non-toxic anti-viral; it does not eliminate the latent virus
What is erythema multiforme?
Hypersensitivity reaction usually triggered by infections, most commonly herpes simplex virus (HSV), or drug reactions
Characteristics of erythema multiforme?
Target lesions with erythema shown
