PARVOVIRUS B19 Flashcards
What is the structure of Parvovirus B19?
Parvovirus B19 is a very small virus. The genome is ssDNA virus, non-enveloped, negative polarity, capsid is icosahedral symmetry.
What are the diseases associated with Parvovirus B19?
1- Erythema infectiosum (Slapped cheek syndrome, fifth disease)
2- Aplastic anemia (mostly patients with sickle cell anemia)
3- Fetal infections (Hydrops fetalis)
How is Parvovirus B19 transmitted?
1- Transmission primarily through respiratory route
2- Transplacental transmission
3- Blood transfusions
What are the clinical features of Erythema Infectiosum (Fifth Disease)?
I.P. = 4-14 days but may extend to 20 days. Mild disease usually during childhood. Bright red rash most prominent on the cheeks, with low-grade fever, runny nose (coryza), and sore throat. A ‘lacy,’ less intense, erythematous rash appears on the body. Resolve within about one week.
What is the pathogenesis of Hydrops fetalis caused by Parvovirus B19?
Hydrops fetalis presents with massive edema of the fetus secondary to congestive heart failure resulted from severe anemia caused by death of parvovirus B19 infected erythroblasts in fetus.
What are the clinical presentations of Parvovirus B19 infection in adults?
Infection in adults, especially women, can cause arthritis may involve small joints of the hands & feet bilaterally same as rheumatoid arthritis.
How is Parvovirus B19 infection diagnosed?
1- Detection of specific IgM antibodies to B19 virus
2- Isolation of virus from throat swabs, but this is not usually done
3- Molecular method: PCR for detection of viral DNA in blood can be used especially immunocompromised patients because antibodies may not be detectable
4- Fetal infection can be determined by PCR analysis of amniotic fluid
What is the treatment for Parvovirus B19 infection?
No specific treatment of B19 infection. Pooled Igs to patients with immunodeficiencies who have chronic B19 infection. There is no vaccine available.
What is the significance of Parvovirus B19 replication in the S phase of the cell cycle?
It replicates only when a cell is in S phase, this explains that virus replicates in red cell precursors but not in mature red cells.
What are the risk groups for severe complications from Parvovirus B19 infection?
Patients with chronic anemia like sickle cell anemia, thalassemia, and spherocytosis, can suffer from transient but severe aplastic anemia (aplastic crisis). People with immunodeficiencies such as HIV-infection, chemotherapy, transplant patients can have chronic anemia, leukopenia, or thrombocytopenia as a result of chronic B19 infection.
