25 - 165 - VARICELLA AND HERPES ZOSTER Flashcards
What virus causes varicella?
varicella-zoster virus (VZV)
What virus causes herpes zoster
varicella-zoster virus (VZV).
Clinical manifestations of varicella
The rash of varicella usually begins on the face and scalp and spreads rapidly to the trunk, with relative sparing of the extremities. Lesions are scattered, rather than clustered, reflecting viremic spread to the skin, and they progress sequentially from rose-colored macules to papules, vesicles, pustules, and crusts. Lesions in all stages are usually present at the same time.
Compare the severity of varicella in children and adults
In immunocompetent children, systemic symptoms are usually mild and serious complications are rare.
In adults and immunocompromised persons of any age, varicella is more likely to be severe and can be associated with life-threatening complications.
Herpes zoster is most common in what population
Older adults and immunocompromized individuals
Most common debilitating complication of herpes zoster
Chronic neuropathic pain (Postherpetic neuralgia)
Varicella is common in what age population
Children
Infectious period of varicella
1-2 days before appearance of exanthem until 4 - 5 days therafter, until all vesicles have crusted
Mean incubation period of varicella infection
14 - 17 days
major route by which varicella is acquired and transmitted
respiratory tract by airborne droplets or aerosols, but infection also may be spread by direct contact
T/F: Varicella crusts are not infectious
True
occurs in individuals who develop varicella early in infancy in the presence of maternal antibody or following postexposure prophylaxis with varicella-zoster immune globulin or varicella vaccine
Modified varicella
occurs when vaccinated individuals are reinfected following exposure to wildtype VZV
Breakthrough varicella
T/F: Herpes zoster can be acquired through exposure to Varicella and herpes zoster
False
There is no convincing evidence that herpes zoster can be acquired by contact with persons with varicella or herpes zoster. 1 Rather, the incidence of herpes zoster is determined by factors that influence the host–virus relationship and the presence of immune responses necessary to prevent reactivation of latent VZV
major risk factor for herpes zoster
- Age
- Decreased VZV-specific cell-mediated immunity (Immunocompromising conditions associated with increased risk of herpes zoster include bone marrow and solid organ transplants, hematologic and solid tumor malignancies, and immune-mediated diseases (eg, systemic lupus erythematous, rheumatoid arthritis)
- Other factors reported to correlate with the risk of herpes zoster include female sex, 32 physical trauma in the affected dermatome, 46 IL-10 gene polymorphisms,47 family history of herpes zoster, 48-50and white race
characteristic feature of varicella lesions
A characteristic feature of varicella lesions is their rapid progression, over as little as 12 hours, from rosecolored macules to papules, and then to vesicles, pustules, and crusts
Describe the typical vesicle of varicella
The typical vesicle is 2 to 3 mm in diameter and elliptical, with its long axis parallel to the folds of the skin. The early vesicle is superficial and thin-walled, and surrounded by an irregular area of erythema, which gives the lesions the appearance of a “dewdrop on a rose petal.
distinctive feature of varicella
simultaneous presence, in any one area of the skin, of lesions in all stages of development
Prodrome in varicella is more common what age group
Older children and adults
In young children, prodromal symptoms are uncommon. In older children and adults, the rash is often preceded by 2 to 3 days of mild fever, chills, malaise, headache, anorexia, backache and, in some patients, sore throat and dry cough.
Most common complication of varicella in normal children
Secondary bacterial infection of skin lesions, usually by Staphylococci or Streptococci, which may produce impetigo, cellulitis, erysipelas, and, rarely, necrotizing fasciitis
Can varicella produce bullous lesions?
Yes.
Bullous lesions may develop when vesicles are superinfected by Staphylococci that produce exfoliative toxins.
characterize varicella in adults based on symptoms, rash and complications
In adults, fever and constitutional symptoms are more prominent and prolonged, the rash of varicella is more profuse, and complications are more frequent.
major severe complication of varicella in adults
Varicella Pneumonia
Varicella pneumonia is characterized by cough, dyspnea, tachypnea, high fever, pleuritic chest pain, cyanosis, and hemoptysis beginning 1 to 6 days after rash onset.
The severity of the symptoms usually exceeds the physical findings, but imaging typically reveals diffuse, peribronchial nodular densities throughout both lung fields with a tendency to concentrate in the perihilar regions and at the bases. The mortality in adults with frank varicella pneumonia is estimated to be between 10% and 30%, but it is less than 10% if immunocompromised patients are excluded and patients receive prompt antiviral therapy
The highest risk (2%) of occurrence of congenital varicella syndrome when maternal varicella occurs between what AOG?
13 - 20 weeks AOG.
varicella-associated Reye syndrome (acute encephalopathy with fatty degeneration of the liver) may occur in patients treated with what drug?
Salicylates
In herpes zoster, Pain and paresthesia in the involved dermatome often precede the eruption by how many days
1 to 3 days but occasional a week or longer
A few patients experience acute segmental neuralgia without ever developing a cutaneous eruption—a condition known as
zoster sine herpete
Most frequently affected nerve in herpes zoster
trigeminal nerve, particularly the ophthalmic division (10%-15%), and the trunk from T3 to L2 (>50%),
Differentiate herpes zoster and varicella based on virus spread
intraneural (axonal) spread of virus to the skin in herpes zoster, as opposed to viremic spread in varicella.
Describe the evolution of lesions of herpes zoster
Herpes zoster lesions begin as erythematous macules and papules in a dermatomal distribution.
Vesicles form within 12 to 24 hours and evolve into pustules by the third day (Fig. 165-3E).
These dry and crust in 7 to 10 days. The crusts generally persist for 2 to 3 weeks.
In normal individuals, new lesions continue to appear for 1 to 4 days (occasionally for as long as 7 days).
The rash is most severe and lasts longest in older people, and is least severe and of shortest duration in children.
What nerve is associated with hutchinson sign
Nasociliary branch of the ophthalmic division of the trigeminal nerve
Involvement of the nasociliary branch, which innervates the eye, as well as the tip and side of the nose, provides VZV with direct access to intraocular structures. Thus, when ophthalmic zoster involves the tip and the side of the nose (Hutchinson sign), careful attention must be given to the condition of the eye.
Involvement of the nasociliary branch is frequently accompanied by unilateral conjunctivitis and impaired corneal sensation, which can lead to corneal ulceration and sight-threatening bacterial infection. The eye is involved in 20% to 70% of patients with ophthalmic zoster.
Syndrome that results from involvement of facial and auditory nerves
Ramsay Hunt syndrome (facial palsy in combination with herpes zoster of the external ear, ear canal, or tympanic membrane, with or without tinnitus, vertigo, and deafness)