Section 5. Viral and Rickettsial Diseases

This condition is a benign viral infection that appears as crops of discrete, slightly umbilicated, flesh-colored, or shiny papules. It is extremely common among children and may be seen in several children within a family. The lesions may become inflamed if traumatized or infected and sometimes become inflamed spontaneously as they resolve. Rarely is there only a solitary lesion; most commonly there are fewer than 20. However, the total number is sometimes in hundreds. The lesions tend to be grouped, and the average size of a lesion is 2–3 mm in diameter and height. The trunk, face, and genitalia are the most common sites of infection. Pruritus is an occasional symptom and may be the impetus for inoculating the viral infection from one area of the skin to another. Molluscum contagiosum is self-limited, but treatment is often required out of concern for appearance. Treatment should be individualized to the age and extent of involvement in each patient. Destruction of lesions with a sharp curette is the preferred mode in a cooperative child with limited disease. The child with numerous lesions poses a particular therapeutic challenge.

Occasionally, a lesion of molluscum contagiosum may grow to as large as 3 cm in diameter. Two such “giant mollusca” are pictured here. The diagnosis is usually suggested by the presence of more typical, smaller lesions on adjacent or distant skin surfaces. Treatment is again by surgical removal when possible. Local anesthesia would be a feasible and a kind thing to administer in such a case.

Many children with molluscum contagiosum infection develop an eczematous, pruritic dermatitis surrounding the affected area of involvement. Low potency topical corticosteroids can alleviate the dermatitis but these medications should not be used chronically. At times, the lesions in the involved area may have to be removed in order to permanently clear the dermatitis.

In some patients when the immune response to the molluscum virus occurs, a hypersensitivity eruption may be noted. This eruption favors the extremities, particularly the elbows (Fig. 5-5) and knees, with skin colored to erythematous papules and papulovesicles which may be grouped. The buttocks may also be involved. Inflamed molluscum is seen elsewhere. Note the inflamed mollusum on the abdomen in this figure.

The common wart is a benign growth caused by localized infection with one of the many types of human papillomavirus. These small DNA viruses are part of the papovavirus group. Warts are especially common among children and adolescents and may occur on any mucocutaneous surface. The hands are a particularly frequent location. The typical wart is a rough-surfaced nodule that may be either lighter or darker than the surrounding skin. Lesions involving the proximal and lateral nail folds are pictured in Fig. 5-6; Fig. 5-7 shows numerous verrucae on the palmar surface. Treatment must be individualized to the age and cooperative abilities of the patient and to the size and location of the wart. Gentle cryotherapy or topical salicylic acid preparations may be of value in the treatment of warts.

In other cases, cryotherapy or treatment with a salicylic acid preparation is preferable. The gentler forms of treatment are particularly good for periungual warts. In those areas, surgery may cause scarring of the nail matrix and nail dystrophy. Following the application of cantharidin or liquid nitrogen, blister formation may result. Upon resolution of the blister, a ring wart may develop, as seen in this figure.

The surfaces of common warts are influenced by their position on the body and by what goes on there. In general, they are rough of surface. On hands, the surfaces of warts are domed from wear and tear, so that troughs and crests are shallow; on soles, they are flat and smooth from the weight of the body, but where they are undisturbed, common warts tend to grow with fimbria or fingerlike projections. They are then called filiform or digitate warts. The face and scalp are the most common sites where warts grow in this fashion.

Plantar warts appear as flat areas of firm hyperkeratosis on the soles of the feet. Lesions that occur at points of pressure may be associated with severe pain on walking. Figure 5-10 illustrates a solitary plantar wart. Note the obliteration of skin markings, which does not occur in a callus. The lesions in Fig. 5-11 are numerous and mosaic. Treatment of plantar warts requires perseverance on the part of both patient and physician. Attempts at a rapid cure may result in scarring. One practical method involves the daily application of salicylic acid plasters or liquid salicylic acid preparations along with repeated paring of the necrotic surface of the wart. The success of this routine may be hastened by gentle cryotherapy. Lesions that are small and in non-weight-bearing areas may be removed by curettage without electrocautery.

Warts with this “cauliflower” appearance on the labia (Fig. 5-12), penis, or around the rectum (Fig. 5-13) are termed condylomata acuminata. The presence of lesions of this type in a child should prompt the physician to consider the possibility of sexual abuse, although the true incidence of this association is not known. In some cases, condylomata acuminata may be the result of innocent contact with another infected individual or perinatal transmission from a mother with cervical or vaginal lesions. Brief application of podophyllum resin is the preferred treatment.

Plane, or flat, warts may be caused by several types of the human papillomavirus. They are common in children. The lesions are slightly raised, flesh-colored papules, and usually 2–4 mm in diameter. The face and hands are the most frequent locations for these multiple small warts. The lesions may be discrete or confluent, and a linear array of flat warts may result from autoinoculation in a scratch. Gentle freezing or chemical destruction is the treatment of choice.

This rare familial disease usually has its onset during childhood. Patients develop numerous flat warts, initially involving the face and upper trunk. A number of human papillomavirus types have been implicated. As the lesions tend toward confluence, they may mimic the appearance of tinea versicolor. Most patients with epidermodysplasia verruciformis have depressed cell-mediated immunity. They are also at risk for squamous cell carcinomas, which generally arise on sun-exposed skin.

Neonatal herpes simplex infection is acquired during passage through an infected birth canal. The cutaneous involvement may be as extensive as pictured here or it may be subtle. The scalp is the most common site for the typical clustered vesicles. Because of the very high frequency of concurrent disseminated disease, cutaneous herpes simplex in the newborn must be considered a pediatric emergency. Early treatment with an intravenous antiviral agent offers the infant the best possibility of survival.

Herpes simplex infection of the distal phalanx may occur in infants and young children. The first episode may accompany herpetic gingivostomatitis. Herpetic whitlow presents with pain or paresthesia and with erythema and vesiculation.

The original infection is occasionally misdiagnosed as bacterial paronychia. Subsequent recurrences of lesions at the same site, which occur in about 20 percent of patients, will lead the practitioner to the correct diagnosis.

Following an episode of primary herpes simplex, the virus may remain dormant within a nerve ganglion. A number of triggering factors including febrile illness, emotional or physical stress, excessive sun exposure, and trauma may cause the virus to replicate and spread to the skin surface. The typical “fever blister” or “cold sore” is a recurrent herpes simplex infection on the lip or vermilion border. Genital herpes simplex infection, more often than not, is also characterized by periodic recurrence. Patients with recurrent disease will often experience prodromal pain or paresthesia in the involved area. Most episodes last from 7 to 10 days. Represented here are lesions on the face (Fig. 5-19) and on the knee (Fig. 5-20). The latter is a less common location serving to illustrate that recurrent herpes simplex may occur on any area of the skin.

Illustrated here is a severe case of recurrent herpes simplex on the eyelids, cheek, and nose. Without a clear history of recurrence, herpes zoster would enter into the differential diagnosis. Repeated corneal ulceration, with scarring, may lead to visual impairment. Herpes simplex keratitis has become the major cause of infectious blindness in the United States.

Herpes simplex infection in the genital region is a sexually transmitted disease. It is common in the sexually active adolescent as pictured here. In the young child, genital herpes simplex should create a high index of suspicion for sexual abuse. This figure illustrates the multiple painful erosions that may occur in primary infection. Regional lymphadenopathy and fever may also be present. Recurrences of genital herpes are very common but are generally much milder in both extent and duration than the primary disease.

Disseminated cutaneous herpes simplex infection is a serious complication of atopic dermatitis. It may also occasionally occur in individuals with other dermatologic disorders. Patients rapidly develop numerous umbilicated vesicles in the areas of eczematous involvement. Children with eczema herpeticum often become seriously ill with high fever. Bacterial superinfection and sepsis can be a complication, and the disease is occasionally fatal. The patients pictured here developed involvement of the entire skin surface. The lesions in Fig. 5-23 are typical umbilicated vesicles, and the lesions in Fig. 5-24 are equally extensive and are beginning to crust. Skillful and attentive supportive treatment is required in order to maintain fluid and electrolyte balance and prevent superinfection. Treatment with intravenous acyclovir seems to hasten clinical improvement and is often recommended for children with extensive or rapidly increasing involvement.

Chickenpox is caused by a virus of the herpes group. The disease is highly contagious and is spread by droplet or direct contact. The incubation period for chickenpox ranges from 11 to 21 days. Prodromal symptoms consist of low-grade fever, headache, anorexia, and malaise. On the following day, the characteristic rash begins to appear. The lesions evolve from erythematous macules to form small papules. Quickly, a clear vesicle arises on this erythematous base. The classic lesion of chickenpox has been poetically described as a “dewdrop on a rose petal.” Over the next several days, the vesicles rupture and then crust. The rash begins on the chest and back and spreads centrifugally to involve the face, scalp, and the extremities. New lesions of chickenpox arise in crops over a period of several days. Since crops of macules, papules, vesicles, and crusts are successive and overlapping, one sees lesions at all stages of development in given locations. Itching is a symptom and may be severe.

Lesions on the oral mucous membranes, which are common, are pictured in Fig. 5-28. They are most common on the palate and quickly evolve into small, superficial erosions. Figure 5-27 depicts a case of chickenpox of unusual severity. The lesions tend to be large blisters and to become hemorrhagic. Cases of this type are more likely to occur in children with reticuloendothelial malignancies or immunologic defects, or in those under immunosuppressive or prolonged corticosteroid therapy. Complications of chickenpox in these children may include varicella pneumonia, myocarditis, and hepatitis. There are also a number of complications of chickenpox in the child who was previously healthy. Secondary bacterial infection of the skin lesions is by far the most common. Other, less frequent, sequelae include thrombocytopenia, purpura fulminans, and postinfectious encephalitis. Finally, a significant number of cases of Reye's syndrome occur after chickenpox, and aspirin should therefore not be used as an antipyretic.

On rare occasions, the infants of women who develop chickenpox during the first trimester of pregnancy are born with congenital defects. The congenital varicella syndrome is characterized by asymmetrical arm or leg lengths, ocular abnormalities, microcephaly, and intrauterine growth retardation. Cutaneous scarring in a dermatomal distribution is particularly characteristic of the constellation of birth defects caused by the varicella zoster virus.

Maternal chickenpox during several days before or after the birth of a child may lead to a significant health risk for the infant. The newborn who is exposed to varicella without the benefit of transplacental maternal antibody may go on to develop severe disseminated infection with pulmonary and hepatic involvement. This disease may sometimes be fatal. Pictured here are newborns with numerous typical chickenpox lesions. The hemorrhagic lesions that may be part of neonatal varicella are not present in these cases.

Herpes zoster, or shingles, is an acute eruption characterized by vesicles and small bullae. Lesions are usually unilateral and confined to a single dermatome (Fig. 5-32). The cause of herpes zoster is the varicella zoster virus. After an initial episode of chickenpox, the virus lies dormant in the dorsal root or cranial nerve ganglia. Reactivation of the virus, usually years later, leads to the typical eruption. Herpes zoster is a relatively rare disease in children and is seen more frequently in those young people who had chickenpox at a very early age. Localized pain may precede the onset of the rash, but postherpetic neuralgia is unusual in childhood. Children with lesions around the eye or on the tip of the nose may have involvement of the nasociliary nerve and should be observed carefully for ocular involvement. Children with involvement of the ear (Fig. 5-33) may develop severe otalgia and when associated with facial paralysis it is known as Ramsay Hunt syndrome.

The child with herpes zoster may, in the normal course of the illness, develop several chickenpox-like lesions outside of the involved dermatome. However, rapid and widespread evolution of such lesions—generalized herpes zoster—is a problem of greater concern. Hematogenous spread of the viral infection in this fashion may be an indication of an underlying immune deficiency.

Infants born to mothers who developed primary varicella infection during pregnancy may likewise have been infected during fetal life. These infants may develop herpes zoster without a clinical history of previous varicella. Associated with this may be a temporary paresis of the affected area.

This common and benign viral disease of childhood is usually caused by the A16 strain of coxsackievirus, although other strains of the same virus have been implicated. It most often occurs in late summer and early fall. The prodrome consists of low-grade fever and malaise. Shortly thereafter, vesicular lesions arise on the soft palate (Fig. 5-36), tongue, buccal mucosa, and uvula. The lips are usually spared. Occasionally, these lesions may be painful and cause some difficulty in eating. The cutaneous lesions develop 1 or 2 days after those in the mouth. They consist of asymptomatic round or oval vesiculopustules that evolve into superficial erosions. The edges of the palms (Fig. 5-37) and soles (Fig. 5-38) are a favored location.

The dorsae of the hands and feet may also be involved. There is sometimes an accompanying macular and papular eruption on the buttocks. The eruption lasts from 7 to 10 days and no therapy is required. Although culture of the virus is possible, the diagnosis of hand-foot-mouth disease is usually made on clinical grounds.

The worldwide eradication of smallpox has eliminated the need for vaccination with the modified cowpox virus. Over the many years when this medical practice was necessary, a number of benign and some more serious dermatologic complications were observed. The sequelae of smallpox vaccination are as follows: 3–4 days after inoculation, there develops an area of erythema and edema at the injection site (usually an arm or thigh); this rapidly evolves into edema, vesiculation, ulceration, crusting, and scar formation over a period of about 3 weeks. For most children, fever, malaise, and local discomfort are the major side effects. The complications of a severe local reaction (Fig. 5-39) and of a generalized eruption (Figs. 5-39 and 5-40) are illustrated here.

Still another complication of premeditated induction of vaccinia was accidental autoinoculation on an undesirable site while the primary pock was in progress. Autoinoculation then resulted in a new lesion that began in 1 day (a reaction time) and rapidly repeated the whole process. The seriousness of such accidents were site specific: on the face, particularly around the eyes, blindness, and elsewhere on exposed skin, cosmetic defects, were serious consequences.

Disseminated vaccinia was the most dreaded complication of smallpox vaccination. Like eczema herpeticum, eczema vaccinatum occurred in children with underlying eczematous disorders. It was more serious because of the severity of the acute illness, the tendency toward scarring, and a higher incidence of mortality. The illustration suggests that the scarring from eczema vaccinatum can be disfiguring.

A wide variety of enteroviruses of the echovirus and coxsackievirus groups are responsible for similar systemic illnesses and cutaneous eruptions. All these illnesses occur most commonly in the late summer or early fall. In the case of echovirus, there is an incubation period of 3–7 days followed by the sudden onset of fever and myalgia. Some combination of abdominal pain, vomiting, pharyngitis, and cervical adenopathy may also be present. Occasionally, nuchal rigidity may indicate the presence of aseptic meningitis. The eruption begins to develop on the face (Fig. 5-43) and within hours, generalization to the trunk (Fig. 5-44) and limbs occurs. The lesions, which are erythematous, papular, and rubelliform, persist for about 3–5 days and then recede. Occasionally, the virus can be recovered from throat, urine, or stool. There is no specific treatment, and little more than simple supportive therapy is required until spontaneous recovery takes place.

Roseola is a common childhood illness that is now known to be caused by human herpes virus 6. Most cases occur during the first year of life. The disease is characterized by 3–5 days of high fever accompanied by minimal constitutional symptoms. Pharyngitis, periorbital edema, and cervical adenopathy may be present and febrile convulsions sometimes occur. The disappearance of fever is accompanied by the onset of rash. The typical eruption is macular and papular, and it is concentrated on the neck and trunk. The eruption clears in hours or at most a day or two.

This condition of unknown etiology begins as an eruption in a periflexural area, the axillary fold being the most common. Other flexural areas including the inguinal fold and popliteal areas may be involved initially. The eruption then spreads unilaterally in an asymmetric fashion, at times involving an entire side of the body. The eruption may then generalize to the rest of the body typically maintaining predominance on the original side. Clinically, the eruption is scalitiniform or eczematous in nature. About 50 percent of patients may develop pruritus. Spontaneous resolution usually occurs in 4–6 weeks.

This condition is characterized by the eruption of firm erythematous papules on the extremities, cheeks, and buttocks. The papulonodular lesions may become confluent in some areas. This disease was originally seen in children with anicteric hepatitis B infection in Europe. Since that time, this syndrome has been found to occur primarily in association with Epstein-Barr virus infection, although other causes include coxsackie, parainfluenza, poliovirus, vaccinia, β-hemolytic streptococcus, and bacille Calmette-Guérin (BCG). The disease is self-limiting, lasting 6–8 weeks.

Congenital infection with cytomegalovirus, a DNA virus of the herpes group, results in disease of varying severity. While some neonates are completely asymptomatic, severely affected infants display intrauterine growth retardation, microcephaly, and hepatosplenomegaly. The cutaneous manifestations, pictured here, are petechiae and purpura. The “blueberry muffin” spots are an indication of extramedullary hematopoiesis. Culture of the virus from urine is the most specific means of diagnosis.

In utero infection by the rubella virus during the first 20 weeks of gestation may result in severe multisystem involvement and a variety of developmental defects. Illustrated here are the dark-blue-to-purple “blueberry muffin” lesions in the severely affected neonate. They are a sign of extramedullary hematopoiesis. Thrombocytopenic purpura is an additional cutaneous manifestation. Congenital cataracts, deafness, and cardiac malformations form a classic triad in infants with the severe intrauterine infection.

This viral disease affects both children and young adults. A mild prodrome consists of headache, coryza, and low-grade fever. The rash itself varies enormously in its course and duration. Most typically, it begins on the face and neck and spreads to the trunk and extremities, as pictured here, over 1–2 days. The lesions are small pink macules and maculopapules, which rapidly coalesce and then fade. The rash is so evanescent that it may begin to disappear on the face before developing on the trunk and extremities. Petechiae on the soft palate, termed Forchheimer's sign, are present in some patients (Fig. 5-53). Systemic illness is generally mild. Enlargement of suboccipital and posterior auricular lymph nodes is a characteristic physical finding. The most serious aspect of rubella is the severe developmental defects that may result from intrauterine infection during the first trimester. Routine childhood immunization has resulted in fewer epidemics and therefore in a lower incidence of viral exposure to pregnant women.

Rubeola, or measles, is a systemic illness caused by an RNA paramyxovirus. The incidence of this previously common childhood disease has decreased markedly since the advent of an effective vaccine, but measles has by no means been eradicated. After an incubation period of 1–2 weeks, the infected child develops fever, conjunctivitis, photophobia, and a distinctive brassy or barking cough. Frequently, the fever and constitutional symptoms are severe. A day or two after the onset of these constitutional signs and symptoms, the enanthem (Koplik's spots) appears as bright-red puncta with central blue-white flecks on the buccal mucosa opposite the second molars (Fig. 5-54). The characteristic rash is maculopapular and erythematous. It begins on the forehead and behind the ears and spreads to the face (Fig. 5-55), neck, trunk, and extremities. The rash disappears in the same sequence, sometimes leaving areas of fine desquamation. The duration of the entire illness is usually 5–7 days.

This picture shows the “measly” appearance of a child who clearly feels miserable. The disease is brief and self-limited for most children, and the treatment is entirely supportive. The incidence of complications is higher, however, than in other childhood exanthems. Otitis media is the most common. Serious complications include bronchopneumonia and encephalitis, which may cause permanent neurologic damage. Subacute sclerosing panencephalitis is a late sequela of measles.

Children who received the “killed” measles vaccine, available during the mid-1960s, may have developed “atypical measles” upon exposure to the virus as young adults. This disease is characterized by high fever and severe respiratory symptoms. The accompanying rash is frequently compared to that of Rocky Mountain spotted fever (Figs. 5-60 and 5-61). The exanthem, which typically begins on the hands and feet, maybe macular, vesicular, or purpuric. Children who receive the live attenuated measles vaccine, which is currently in use, are not susceptible to atypical measles.

This self-limited febrile illness is caused by Rickettsia akari. It is transmitted to man by a mite that is an obligatory parasite of the common house mouse. One to two weeks after exposure, a nodule develops at the point of entry of a parasitized mite. The nodule becomes vesicular and then crusted with a black eschar (the pock, seen well developed on the neck in Fig. 5-58). Regional lymphadenopathy is usually present. Within several days, the patient develops intermittent fever, photophobia, headache, myalgia, and lassitude. Two to three days later, a generalized exanthem, consisting of discrete macules that quickly become papular, appears (Fig. 5-59). Firm vesiculopustules arise atop the papules and these subsequently form crusts. The eruption lasts for 1–2 weeks. Unlike Rocky Mountain spotted fever, rickettsialpox shows a negative Weil-Felix reaction.

This disease is caused by Rickettsia rickettsii and is transmitted by a number of different ticks. Despite its geographical title, Rocky Mountain spotted fever is present in many locations throughout the United States and the entire Western Hemisphere. After infection by tick bite, there is an incubation period of 2–14 days. The abrupt onset of the disease includes severe headache, fever, chills, arthralgia, and myalgia. After 2–3 days of these constitutional symptoms, erythematous macules erupt on the wrists, hands, forearms, legs, and ankles, as seen in these figures. Lesions then spread to the palms and soles and the trunk. The macules originally blanch with pressure but soon become purpuric and even necrotic. The disease causes a severe vasculitis and complications include disseminated intravascular coagulation, hemorrhage into the gastrointestinal and urinary tracts, and cardiovascular collapse. The Weil-Felix test is positive, but the disease must be treated immediately upon clinical suspicion. The high fatality rate is markedly reduced by prompt antibiotic therapy.

Erythema infectiosum is a mild childhood disease that is caused by human parvovirus B19. This condition develops after a mean incubation period of 14 days. There are few if any prodromal symptoms. The rash evolves in three clinical stages. The first stage is characterized by the abrupt appearance of a bright-red malar blush. The appearance is so startling that it has been given the suggestive description of “slapped cheeks” (Figs. 5-62 and 5-63). During the second stage, the facial rash begins to fade, and a maculopapular, urticarial, or morbilliform exanthem develops on the extremities and trunk. Pruritus may be present.

As portions of this rash fade over a period of several days, a reticular pattern emerges, mainly on the extremities, which gives the arms and legs a marbled appearance (Fig. 5-64). This reticular eruption, which is the third stage of the disease, may last for only 1 week, or it may last continuously or by relapses for as long as 8 weeks. Exercise and variations in temperature may make the rash appear more or less prominent. No treatment is required.

In its most characteristic form, patients develop numerous purpura on the hands and feet, with sharp demarcation at the wrists and ankles. Other areas of involvement may include the face, buttocks, and inguinal creases. This syndrome was originally described in conjunction with parvovirus B19 infection, but it has also been attributed to measles virus, cytomegalovirus, Coxsackie virus B6, human herpesvirus 6, and hepatitis B. Systemic symptoms are rare and the condition usually resolves in 1–2 weeks.