Roseola
Roseola infantum, also known as exanthema subitum and sixth disease, is a common mild acute febrile illness of childhood caused by infection with human herpesvirus (HHV) 6 (the primary agent causing roseola) or 7 (a secondary causal agent for roseola).15 HHV-6 has 2 variants (HHV-6a and HHV-6b). Roseola infantum is mostly associated with the HHV-6b variant, which predominantly affects children 6 to 36 months of age.16
The virus replicates in the salivary glands and is shed through saliva, which is the route of transmission. After a 10- to 15-day incubation period, it remains latent in lymphocytes and monocytes, thus persisting in cells and tissues. It may reactivate late in life, particularly in immunosuppressed individuals. Reactivated infection in immunocompromised patients may be associated with serious illness such as encephalitis/encephalopathy. In patients who have received a bone marrow transplant, it can induce graft vs host disease.17
Presentation. The virus causes a 5- to 6-day illness characterized by high fever (temperature as high as 105°-106° F), miringitis (inflammation of tympanic membranes), and irritability. Once defervescence occurs, an erythematous morbilliform exanthem appears.The rash, which has a discrete macular/papular soft-pink appearance, starts on the trunk and spreads centrifugally to the extremities, neck, and face (FIGURE 2). It usually resolves within one to 2 days.
Complications. The most common complication of roseola is febrile seizures.17 Less common ones include encephalitis, encephalopathy, fatal hemophagocytic syndrome,18 or fulminant hepatitis.19
Treatment and prevention. Treatment depends on symptoms and may include antipyretics for fever management and liquids to maintain hydration. Recovery is usually complete with no significant sequelae. If a child develops a seizure, no antiepileptic drugs are recommended. No vaccine exists.
Fifth disease
Human parvovirus B19, a minute ssDNA virus, was first associated with human disease in 1981, when it was linked to an aplastic crisis in a patient with sickle cell disease.20 Since then researchers have determined that it is also the cause of erythema infectiosum or fifth disease of childhood. The B19 virus can also cause anemia in the fetus as well as hydrops fetalis. It has been linked to arthralgia and arthritis (especially in adults). There is an association with autoimmune diseases with characteristics similar to rheumatoid arthritis.20
The B19 virus is transmitted via aerosolized respiratory secretions, contaminated blood, or the placenta. The virus replicates in erythroid cells in bone marrow and peripheral blood, thus inhibiting erythropoiesis.21 Once the rash appears, the virus is no longer infectious.22 Seasonal peaks occur in the late winter and spring, with sporadic infections throughout the year.23 More than 70% of the adult population is seropositive for this virus.20
Presentation. Erythema infectiosum is a mild illness in childhood with an incubation period of 6 to 18 days. It presents with a characteristic malar rash on the face that gives patients a slapped cheek appearance (FIGURE 3A). A softer pink-colored “lacy” reticulated rash that blanches when touched may appear on the trunk, arms, and legs (FIGURE 3B).
Another presentation, which involves the hands and feet (glove and sock syndrome) (FIGURES 3C and 3D), consists of a purpuric eruption with painful edema and numerous small confluent petechiae.22,24 A majority of patients present with inflammatory symptoms that tend to resolve without sequelae within 3 weeks of infection.23
A rash is not as prevalent in adults as in children. Adults often present with more systemic systems, such as a debilitating influenza-like illness, arthropathy, transient aplastic anemia in sickle cell-affected individuals, and persistent viral suppression of erythrocyte production in immunocompromised patients and organ-transplant recipients.
Complications. The B19 virus can cause spontaneous abortion in pregnant women and anemia and hydrops fetalis in the fetus.22 Arthritis can occur in children, but is more common in adults, especially in women. The arthritis tends to be symmetrical and affects small joints such as the hands, wrists, and knees.
In one study of parvovirus B19 involving 633 children with sickle cell disease, 68 children developed transient red cell aplasia, 19% of them developed splenic sequestration, and 12% developed acute chest syndrome, a lung-related complication of sickle cell disease that can lower the level of oxygen in the blood and can be fatal.25
Treatment and prevention. Treatment of B19 infection is symptomatic; for example, nonsteroidal anti-inflammatory drugs (NSAIDs) are used if joint pain develops. No vaccine exists.
Hand, foot, and mouth disease
Hand, foot, and mouth disease (HFMD) is caused by the picornavirus family, including the Coxsackievirus, Enterovirus, and Echovirus. Infections commonly occur in the spring, summer, and fall. The virus primarily affects infants and children <10 years of age with the infection typically lasting 7 to 10 days.26