Abstract
BackgroundHuman parvovirus B19 is the etiologic agent of erythema infectiosum in children. It is also associated with other clinical manifestations in different target groups. Patients with chronic hemolytic anemia are at high risk of developing acute erythroblastopenia following infection by the virus. They usually become highly viremic and pose an increased risk of virus transmission. Close monitoring of such high risk groups is required for epidemiologic surveillance and disease prevention activities. Here we report a molecular epidemiological study on B19 virus infection in Tunisian patients with chronic hemolytic anemia.MethodsThis study was conducted on 92 young chronic hemolytic anemia patients who attended the same ward at the National Bone Marrow Transplantation Center of Tunis and 46 controls from a different hospital. Screening for IgM and IgG anti-B19 antibodies was performed using commercially available enzyme immunoassays and B19 DNA was detected by nested PCR in the overlapping VP1/VP2 region. DNA was sequenced using dideoxy-terminator cycle sequencing technology.ResultsAnti-parvovirus B19 IgG antibodies were detected in 26 of 46 sickle-cell anemia patients, 18 of 46 β-thalassemia and 7 of 46 controls. Anti-parvovirus B19 IgM antibodies were detected only in 4 of the sickle-cell anemia patients: two siblings and two unrelated who presented with acute erythroblastopenia at the time of blood collection for this study and had no history of past transfusion. B19 DNA was detected only in sera of these four patients and the corresponding 288 bp nested DNA amplicons were sequenced. The sequences obtained were all identical and phylogenetic analysis showed that they belonged to a new B19 virus strain of Genotype1.ConclusionA new parvovirus B19 strain of genotype1 was detected in four Tunisian patients with sickle-cell anemia. Virus transmission appeared to be nosocomial and resulted in acute erythroblastopenia in the four patients. The possibility of independent transmission of this B19 variant to the patients is unlikely in light of the present epidemiological data. However this possibility cannot be ruled out because of the low genetic variability of the virus.
Highlights
Human parvovirus B19 is the etiologic agent of erythema infectiosum in children
In these diseases erythroïd progenitor cell formation is increased to compensate for red blood cell lysis and B19 infection can suppress erythropoïesis and induce acute erythroblastopenia often referred to as transient aplastic crisis [13]
The chronic hemolytic anemia patients attended the same ward at the National Bone Marrow Transplantation Center of Tunis for treatment and follow up, and the control group was from the Charles Nicolles Hospital, Tunis
Summary
Human parvovirus B19 is the etiologic agent of erythema infectiosum in children. It is associated with other clinical manifestations in different target groups. Human parvovirus B19 belongs to the Erythrovirus genus of the Parvoviridae family and is the etiologic agent of erythema infectiosum or fifth disease in children [1,2] Infections with this virus are very common and can result in a wide range of clinical manifestations depending on the patient's immunological and hematological status. Patients with hematological disorders are at risk of severe clinical illness especially in chronic hemolytic anemia such as sickle cell disease [9,10], thalassemia [11] and hereditary spherocytosis [12] In these diseases erythroïd progenitor cell formation is increased to compensate for red blood cell lysis and B19 infection can suppress erythropoïesis and induce acute erythroblastopenia often referred to as transient aplastic crisis [13]. Close monitoring of such high risk groups for this viral infection is, of great importance for epidemiologic surveillance and disease prevention
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