Other Viral Diseases

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Other Viral Diseases

Viral infections frequently have cutaneous manifestations, especially in children. This chapter covers classic childhood exanthems, poxvirus infections, and several other viral infections with characteristic skin findings. Nonspecific viral exanthems, typically presenting with blanchable erythematous macules and papules in a widespread distribution, are also common in children infected with enteroviruses (see below) and a variety of respiratory viruses, generally resolving spontaneously within a week. Fig. 68.1 outlines clinical features to consider when evaluating a patient with a morbilliform (‘maculopapular’) exanthem, and Chapter 3 addresses considerations in patients with fever and a rash. HIV, human papillomavirus, and herpesvirus (including infectious mononucleosis and roseola infantum) infections are discussed in Chapters 65–67.

Fig. 68.1 Approach to the patient with a presumed morbilliform or macular/papular viral exanthem. *Gram-positive rod; may result in severe pharyngitis and scarlatiniform exanthem in adolescents and young adults. ^†Intracellular inclusions in endothelial cells are another finding. **Usually febrile seizures.

Enterovirus Infections

• Non-polio enteroviruses (e.g. coxsackieviruses, echoviruses) are single-stranded RNA picornaviruses with a worldwide distribution; they cause a variety of exanthems, enanthems, and systemic manifestations.

• Spread via fecal–oral (e.g. swimming pools, ingestion of oysters) and respiratory routes, with an incubation period of 3–6 days; most common in the summer and fall in temperate climates, favoring young children.

• Hand, foot, and, mouth disease (HFMD; in the United States, coxsackievirus A16 > others) features oval vesicles on the hands and feet (palms/soles > dorsally) and buttocks plus an erosive stomatitis (e.g. tongue, buccal mucosa, palate, tonsils), often associated with fever and malaise (Fig. 68.2A–D); onychomadesis occasionally occurs 1–2 months later.

Fig. 68.2 Hand, foot, and mouth disease (HFMD). A Oval vesicle and erythematous macules on the plantar surface. B Multiple erythematous macules on the palm, some with a dusky appearance reminiscent of erythema multiforme. C Small oval erosions on the buccal mucosa resembling aphthae. D Discrete erythematous papules and crusted erosions in an area of previous diaper dermatitis. The differential diagnosis in this patient with coxsackievirus A6 infection might include eczema herpeticum. E Extensive vesicles and crusts in the perioral area in a patient with HFMD due to coxsackievirus A6. Herpes simplex virus infection or impetigo may be considered in the differential diagnosis for lesions in this location. Note koebnerization to the site of a healing laceration on the chin. A, B, D, E, Courtesy, Julie V. Schaffer, MD; C, Courtesy, Kalman Watsky, MD.

• Recently, coxsackievirus A6 infection has been associated with a more widespread vesiculobullous exanthem favoring the perioral area, extremities > trunk, and areas of previous dermatitis (‘eczema coxsackium’) or injury as well as the classic sites of HFMD (Fig. 68.2B, D, E; see Fig. 3.5B, C).

• Herpangina presents with fever and oropharyngeal erosions, but usually no exanthem.

• The diverse spectrum of enteroviral exanthems also includes morbilliform, scarlatiniform, Gianotti–Crosti syndrome-like, petechial, and pustular eruptions (see Fig. 3.5A); eruptive pseudoangiomatosis is an uncommon manifestation.

• Organ systems that can be affected by enteroviral infections include the respiratory (upper > lower) and gastrointestinal tracts, liver, CNS (meningitis > encephalitis; especially with enterovirus 71), eyes (hemorrhagic conjunctivitis), joints, muscles, and heart.

• Spontaneous resolution typically occurs within 1–2 weeks.

Measles (Rubeola)

• Incidence has decreased dramatically since introduction of a live vaccine for this single-stranded RNA paramyxovirus in 1963; however, measles outbreaks still occur in both low- and high-income countries, often because of unfounded fears of vaccination.

• Highly contagious and spread by respiratory droplets, with an incubation period of 10–14 days.

• Prodrome of fever, cough, coryza, and conjunctivitis (the 3 C’s), followed in 2–4 days by the appearance of pathognomonic Koplik spots (gray-white papules on the buccal mucosa).

• An exanthem develops 3–5 days after the onset of symptoms, with erythematous macules and papules spreading cephalocaudally from the forehead, hairline, and behind the ears to the trunk and extremities (Fig. 68.3); after 5 days, the eruption fades in the order it appeared.

Fig. 68.3 Measles. Pink macules and minimally elevated papules. Courtesy, Louis Fragola, MD.

• Complications include otitis media, pneumonia, and encephalitis; subacute sclerosing panencephalitis occasionally develops 5–10 years later.

• Atypical measles in the setting of partial immunity features high fevers, cough, and a variable exanthem that may be vesicular, petechial, or associated with acral edema.

• Rx: vitamin A administration for children with acute disease; prevention via vaccination.

Rubella (German Measles)

• Incidence has markedly declined since introduction of a live vaccine for this single-stranded RNA togavirus in 1969.

• Spread via respiratory droplets, with an incubation period of 16–18 days.

• Mild prodrome of fever, headache, and upper respiratory symptoms, followed in 1–5 days by an eruption of erythematous macules and papules that spreads downward from the face and lasts ~3 days; Forchheimer’s spots (red or petechial macules on the soft palate) and tender lymphadenopathy (especially occipital and posterior auricular) are characteristic findings.

• Although usually self-limited, complications include arthralgias/arthritis (especially in adolescent girls and women), thrombocytopenia, and encephalitis.

• Congenital rubella syndrome, most common with maternal infection in the first 16 weeks of pregnancy; can result in cataracts, deafness, congenital heart defects, and microcephaly; a ‘blueberry muffin baby’ presentation occasionally occurs (see Fig. 67.15).

Parvovirus B19 Infection (Erythema Infectiosum, Fifth Disease, ‘Slapped Cheek Disease’)

• Single-stranded DNA virus with tropism for erythroid progenitor cells; found worldwide.

• Transmitted via respiratory secretions and blood products as well as vertically from mother to fetus, with an incubation period of 4–14 days; peak incidence in the winter and spring, favoring children 4–10 years of age.

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