Clinical Findings of Parvoviruses
المؤلف:
Stefan Riedel, Jeffery A. Hobden, Steve Miller, Stephen A. Morse, Timothy A. Mietzner, Barbara Detrick, Thomas G. Mitchell, Judy A. Sakanari, Peter Hotez, Rojelio Mejia
المصدر:
Jawetz, Melnick, & Adelberg’s Medical Microbiology
الجزء والصفحة:
28e , p460
2025-11-02
42
A. Erythema Infectiosum (Fifth Disease)
The most common manifestation of human parvovirus B19 infection is erythema infectiosum, or Fifth disease. This erythematous illness is most common in children of early school age and occasionally affects adults. Fever and mild constitutional symptoms may accompany the rash, which has a typical “slapped cheek” appearance (Figure 1). Both sporadic cases and epidemics have been described. Joint involvement due to immune complex deposition is a prominent feature in adult cases; joints in the hands and the knees are most frequently affected. The symptoms mimic rheumatoid arthritis, and the arthropathy may persist for weeks, months, or years.
Fig1. Erythema infectiosum (fifth disease). Typical “slapped cheek” appearance of the rash on the face. (Courtesy of Dr. Philip S. Brachman, CDC Public Health Image Library.)
The incubation period is usually 1–2 weeks but may extend to 3 weeks. Viremia occurs 1 week after infection and persists for about 5 days. During the period of viremia, virus is present in nasal washes and gargle specimens, identifying the upper respiratory tract—most probably the pharynx—as the site of viral shedding. The first phase of illness occurs at the end of the first week; symptoms are flu like, including fever, malaise, myalgia, chills, and itching. The first episode of illness coincides in time with viremia and reticulocytopenia and with detection of circulating IgM–parvovirus immune complexes. After an incubation period of about 2 weeks, a second phase of illness begins. The appearance of an erythematous facial rash and a lace like rash on the limbs or trunk may be accompanied by joint symptoms, especially in adults. The illness is short lived, with the rash fading after 2–4 days, although the joint symptoms may persist longer. Specific IgG antibodies appear about 15 days postinfection.
B. Transient Aplastic Crisis
Parvovirus B19 is the cause of transient aplastic crisis that may complicate chronic hemolytic anemia, such as in patients with sickle cell disease, thalassemias, and acquired hemolytic anemias in adults. Transient aplastic crisis may also occur after bone marrow transplantation. The syndrome is an abrupt cessation of red blood cell synthesis in the bone marrow and is reflected by the reduction of erythroid precursors in the marrow, accompanied by a rapid worsening of anemia. The infection lowers production of erythrocytes, causing a reduction in the hemoglobin level of peripheral blood. The temporary arrest of production of red blood cells becomes apparent only in patients with chronic hemolytic anemia because of the shortened life span of their erythrocytes; a 7-day interruption in erythropoiesis would not be expected to cause detectable anemia in a normal person. Few anemia patients have a rash. Symptoms of transient aplastic crisis occur during the viremic phase of infection.
C. B19 Infection in Immunodeficient Patients
B19 may establish persistent infections and cause chronic suppression of bone marrow and chronic anemia in immunocompromised patients. The disease is called pure red cell aplasia. The anemia is severe, and patients are dependent on blood transfusions. It has been observed in patient populations with congenital immunodeficiency, malignancies, AIDS, and organ transplantation.
D. B19 Infection During Pregnancy
Maternal infection with B19 virus may pose a serious risk to the fetus, resulting in hydrops fetalis and fetal death due to severe anemia. The overall risk of human parvovirus infection during pregnancy is low; fetal loss occurs in fewer than 10% of primary maternal infections. Fetal death occurs most commonly before the 20th week of pregnancy. Although there is frequent intrauterine transmission of human parvovirus (with estimates of vertical transmission rates of 30% or higher), there is no evidence that most B19 infections cause physical abnormalities. Maternal–fetal transmission may occur most commonly in pregnant women with high plasma viral loads.
E. Human Bocavirus Respiratory and Gastrointestinal Infections
Human bocavirus has been detected in 1.5–11.3% of respiratory tract samples from young children with respiratory infections. It is prevalent among children with acute wheezing. However, bocavirus is often found in mixed infections with other viruses and in asymptomatic individuals, so it remains unclear whether bocavirus is the cause of acute respiratory disease in children. The virus has been detected in about 3% of stool samples from children with acute gastro enteritis. Coinfection rates with other enteric pathogens are also high, so any causative role of bocavirus in gastroenteritis remains uncertain.
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