PANCE Blueprint Infectious Disease (6%)

5 y/o with new, pruritic, painful, vesicular rash

Patient with varicella (chickenpox) will present as → a 3-year-old with fatigue, irritability, and a low-grade fever that he has had for 3 days. According to the patient's mom, the child attends a daycare where a virus is “going around.” On physical examination, the child does not look ill. His temperature is 98.6 F (38 C). His skin examination shows scattered, small vesicles on an erythematous base. The rash was seen first on the face and seems to be spreading to the trunk.

5 y/o with leg pain and rash

Patient with herpes zoster (shingles) will present as → a 67-year-old male who presents to your clinic with a two-day history of a painful rash on his left flank and radiating to his back. This was preceded by burning pain in the same region several days prior. The patient does not recall any history of childhood exanthems and is not up to date on his immunizations. Vital signs are stable. Physical exam reveals a maculopapular rash in a dermatomal distribution on the left flank and extending into the back.

Varicella zoster virus (VZV) is one of the human herpes viruses (HHV3) that cause two diseases: 1. chickenpox (varicella) and 2. herpes zoster (shingles)

• Chickenpox follows initial exposure to the virus and is typically a relatively mild, self-limited childhood illness with a characteristic exanthem, but can become disseminated in immunocompromised children
• Reactivation of the dormant virus results in the characteristic painful dermatomal rash of herpes zoster, which is often followed by pain in the distribution of the rash (postherpetic neuralgia)

1. Varicella (Chicken Pox): primary infections - clusters of vesicles on an erythematous base - dew drops on a rose petal in different stages, starts on the face, and spreads down

• Varicella is transmitted by respiratory droplets and has a 10-20 day incubation period
• The vesicular rash of varicella, which is usually pruritic, appears in successive crops over several days. The lesions begin as macules that rapidly become papules followed by characteristic vesicles; these lesions can then develop a pustular component followed by the formation of crusted papules
• Typically has lesions in different stages of development on the face, trunk, and extremities
• New vesicle formation generally stops within four days, and most lesions have fully crusted by day six
• Crusts tend to fall off within about one to two weeks and leave a temporary area of hypopigmentation in the skin

A child presents with classic itchy red skin spots associated with the chickenpox virus.

2. Herpes Zoster (Shingles): varicella reactivation along one dermatome

• Pain, itching, or tingling in the area where the rash will develop
• A single stripe of vesicles around either left or right side of the body/one side of the face
• Four weeks for the rash to disappear ⇒ pain in affected dermatome > 90 days = postherpetic neuralgia
• Zoster ophthalmicus: shingles involving cranial nerve V (trigeminal nerve), dendritic lesions on slit lamp exam if keratoconjunctivitis is present
• Zoster Oticus (Ramsay-Hunt Syndrome): shingles involving facial nerve (CN VII) otalgia, lesions on the ear, auditory canal and TM, facial palsy auditory symptoms

A single stripe of vesicles around the right side of the body

Diagnosed clinically based on the way the skin lesions appear

• Herpes Zoster can be identified via tzanck smear with visualization of multinucleated giant cells
• Blood tests for varicella antibodies
• PCR to look for viral DNA (most sensitive and is more rapid (≤1 day) compared with conventional culture techniques)
• When PCR testing is not available, DFA testing is performed on scrapings from vesicular skin lesions that have not yet crusted and viral culture

Positive Tzanck test, showing three multinucleated giant cells in center.

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"The Tzanck smear can detect multinucleated giant cells indicative of herpesvirus infections but lacks specificity for VZV and cannot distinguish between herpes simplex virus and VZV infections. When acute diagnostic confirmation is desired, modern tests, such as direct fluorescent antibody (DFA) testing or PCR (if available), are preferred to the Tzanck smear."

Varicella (chickenpox): symptomatic treatment (topical antipruritics and analgesics)

• Antivirals (acyclovir, famciclovir, valacyclovir) may be used in special populations.
• Aspirin should NOT be used ⇒ Reye syndrome
• Varicella-Zoster immune globulin (VZIG)

Varicella-zoster (shingles): acyclovir, famciclovir, valacyclovir given within 72 hours to prevent post-herpetic neuralgia

• Zoster ophthalmicus: oral antivirals, may add acyclovir ophthalmic
• Zoster oticus (Ramsay-Hunt Syndrome): oral acyclovir and corticosteroids
• Postherpetic neuralgia: Both gabapentinoids (ie, gabapentin and pregabalin) and tricyclic antidepressants (TCAs), topical lidocaine gel, capsaicin

Vaccination:

• Varicella Vaccine
  • Children receive the first dose at age 12 through 15 months and the second dose at age 4 through 6 years
  • People 13 years of age and older who have never had chickenpox or never received the chickenpox vaccine should get two doses, at least 28 days apart
  • It is a live-attenuated vaccine:
    • Pregnant women should not get chickenpox vaccine. They should wait to get the vaccine until after they have given birth
    • Women should not get pregnant for 1 month after getting chickenpox vaccine.
    • can be given to patients with HIV who have a CD4+ cell count greater than 200 cells/mm3
• Recombinant zoster vaccine (RZV, Shingrix) is recommended to prevent shingles in adults 50 years and older
  • 2-dose series 2-6 months apart
  • Should be given to patients who previously received Zostavax (ZVL) ⇒ administered at least two months after ZVL