Human Herpesviruses

Published on 05/03/2015 by admin

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Human Herpesviruses

Herpes Simplex Viruses (HSV-1/HHV-1 and HSV-2/HHV-2)

• Ubiquitous pathogens that produce primarily orolabial (HSV-1 > HSV-2) and genital infections (HSV-2 > HSV-1) characterized by recurrent vesicular eruptions (Table 67.1).

• Transmission can occur during both symptomatic and asymptomatic periods of viral shedding.

• Reactivation can occur either spontaneously or due to an appropriate stimulus (e.g. stress, UVR, fever, tissue trauma, or immunosuppression).

• A wide range of clinical presentations exist, with asymptomatic infection being the most common.

• In primary infection.

– Onset is usually 3–7 days after exposure.

– Generalized prodrome (before the onset of mucocutaneous lesions) of tender lymphadenopathy, fever, and malaise; localized pain, burning, and tenderness.

– Initial lesions: small round vesicles on an erythematous base; often painful or burning; the grouping of these vesicles is a clue to the diagnosis; vesicles may become umbilicated or pustular, followed by erosions or ulcerations with hemorrhagic crusts, often with a scalloped border; lesions resolve over 2–6 weeks (Fig. 67.1).

• In reactivation infection.

– Localized prodrome of dysesthesia (e.g. burning/tingling, pain, pruritus) and tenderness.

– Mucocutaneous lesions similar as in primary but fewer in number, less severe, and shorter duration (Fig. 67.2).

• In addition to the classic orolabial and genital infections, HSV can cause other infections (Table 67.2; Figs. 67.3–67.7).

• DDx and Dx: see Table 67.1 and Fig. 67.8.

• Rx: outlined in Table 67.3.

Varicella–Zoster Virus (VZV or HHV-3)

• Primary varicella infection (chickenpox).

– Usually self-limited in otherwise healthy children but more severe with more numerous lesions and a greater risk for complications in adults (including pregnant women) and immunocompromised individuals (Table 67.4; Fig. 67.9).

• Herpes zoster (shingles) – reactivation of VZV.

– Incidence, severity, and risk of complications increase significantly with age and immunosuppression due to a decline in specific cell-mediated immune response to VZV.

– Reactivation results in a sensory neuritis and painful neuralgia, followed by a dermatomal vesicular eruption; clinical course is outlined in Table 67.4 (Figs. 67.10–67.12).

– Exposure of a susceptible person to an individual with chickenpox or zoster can lead to primary varicella but not zoster.

– Rx: early antiviral treatment (within 72 hours of the onset of the first vesicle) is ideal, but initiation after 72 hours but within 7 days may also be helpful (see Table 67.3).

– Selected complications of herpes zoster:

1. Disseminated zoster.

• Defined as >20 vesicles outside the area of the primary or adjacent dermatomes.

• Implies viremia and an increased risk for visceral or CNS involvement (see Table 67.4).

• Requires intravenous acyclovir.

2. Post-herpetic neuralgia (PHN) and post-herpetic itch (PHI).

• Affects 10–15% of patients; incidence and severity increase with age.

• Characterized by persistent pain, dysesthesia (PHN) or pruritus (PHI) along the affected dermatome for weeks to years after the resolution of the eruption.

• Rx: gabapentin, tricyclic anti­depressants (e.g. amitriptyline, nortriptyline); topical agents (e.g. lidocaine patch, capsaicin); oral analgesics (e.g. ibuprofen, opioids).

• Note that opioids are typically ineffective or even aggravating in patients with PHI.

3. Ocular involvement (see Fig. 67.10F).

• Occurs in ~10% of patients, with 20–70% developing ocular disease (occasionally blindness).

• Due to VZV reactivation in the first division of the trigeminal nerve (V1).

• Clues to its diagnosis include lesions in the V1 distribution (see Fig. 67.11), which may be accompanied by unilateral eye pain or conjunctivitis.

• Hutchinson’s sign is the presence of vesicles at the tip, side, or bridge of the nose, indicating involvement of the nasociliary branch of the trigeminal nerve, which also innervates the cornea.

• Initial and longitudinal evaluation by ophthalmology is required.

4. Ramsay–Hunt syndrome (herpes zoster oticus).

• Due to VZV reactivation in the geniculate ganglion.

• Clues to its diagnosis: vesicles in the ear canal, tongue, and/or hard palate.

• Patients may have severe ear pain, acute facial nerve paralysis, and/or taste loss of the anterior two-thirds of the tongue.

• If the vestibulocochlear nerve is also affected, may have tinnitus, hearing loss, or vertigo.

• Consider referral to otolaryn­gology.

[/level-membership-for-dermatology-category][not-level-membership-for-dermatology-category]67

Human Herpesviruses

Herpes Simplex Viruses (HSV-1/HHV-1 and HSV-2/HHV-2)

• Ubiquitous pathogens that produce primarily orolabial (HSV-1 > HSV-2) and genital infections (HSV-2 > HSV-1) characterized by recurrent vesicular eruptions (Table 67.1).

• Transmission can occur during both symptomatic and asymptomatic periods of viral shedding.

• Reactivation can occur either spontaneously or due to an appropriate stimulus (e.g. stress, UVR, fever, tissue trauma, or immunosuppression).

• A wide range of clinical presentations exist, with asymptomatic infection being the most common.

• In primary infection.

– Onset is usually 3–7 days after exposure.

– Generalized prodrome (before the onset of mucocutaneous lesions) of tender lymphadenopathy, fever, and malaise; localized pain, burning, and tenderness.

– Initial lesions: small round vesicles on an erythematous base; often painful or burning; the grouping of these vesicles is a clue to the diagnosis; vesicles may become umbilicated or pustular, followed by erosions or ulcerations with hemorrhagic crusts, often with a scalloped border; lesions resolve over 2–6 weeks (Fig. 67.1).

• In reactivation infection.

– Localized prodrome of dysesthesia (e.g. burning/tingling, pain, pruritus) and tenderness.

– Mucocutaneous lesions similar as in primary but fewer in number, less severe, and shorter duration (Fig. 67.2).

• In addition to the classic orolabial and genital infections, HSV can cause other infections (Table 67.2; Figs. 67.3–67.7).

• DDx and Dx: see Table 67.1 and Fig. 67.8.

image

Fig. 67.8 

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