Erythrovirus B19

B19 virus is the type species of the genus Erythrovirus in the Parvovirinae family of parvoviruses. Parvoviruses infect vertebrates, including fish, birds, reptiles, and mammals. Several different parvoviruses have been identified in humans, including adeno-associated viruses (AAVs), Parv4, human bocavirus, and erythrovirus B19 (formerly parvovirus B19, PVB19).

Erythrovirus B19 (B19V) replicates to high titer and is cytotoxic to erythroid progenitor cells, which are rapidly dividing cells capable of supporting virus replication in peripheral blood and bone marrow. The virus is cytolytic and the infected cell dies. Thus, infection of erythroid progenitor cells suppresses the formation of red blood cells for 5-7 days following infection by the virus. In healthy humans whose red blood cells last for 160 days, this is not a serious event. However, in people suffering from chronic anemias, the inability to synthesize red blood cells for a week may be serious and sometimes fatal. In particular, patients with hemolytic anemia have a low hemoglobin concentration in the blood because their red blood cells have a short life span, only 15-20 days.4



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The number of persons in the U.S. population who test positive for B19V by 2-5 years is 5-10%, by 15 years - 50%, by 30 years - 60%, and by 60 years - 90%. Worldwide, these numbers are similar.5

After an incubation period of about 2 weeks, an infected child experiences typical viral, flu-like symptoms that may last 5-7 days. However, up to 20% of those infected may not experience any symptoms.5 In many individuals the infection passes largely unnoticed and may be accompanied by a range of mild symptoms including rash with a "slapped cheek" appearance, vomiting, aching joints and limbs, general malaise, and fatigue.3

Like rubella, transmission is predominantly by short droplets of short distances, as well as by direct contact with infected body fluids (e.g. saliva). The transmission is facilitated by coughing and sneezing and is highest before the onset of rash and joint pain. B19 virus can also be transmitted by injection or blood transfusion. Infection with B19V usually occurs only once with the production of lifelong neutralizing antibodies. Chronic infections do not occur.3

Diseases

B19 virus is responsible for transient aplastic crisis in patients with a variety of hemolytic anemias, and is the causative agent of erythema infectiosum, a widespread childhood rash-like disease also referred to as "fifth disease." Intrauterine transmission of B19V from an infected mother to her fetus can result in hydrops fetalis (acute or chronic congenital anemia), particularly in the second trimester of pregnancy.1 In adults, B19V is also responsible for acute and chronic polyarthropathy (inflammation of the joints). Immunocompromised patients infected with B19V may develop chronic pure red cell aplasia.2

Complications of infection with B19V in immunocompromised children and adults include hepatitis, myocarditis, encephalitis, meningitis, and damage to small blood vessels. Erythrovirus B19 has been implicated as a causative agent in papillary thyroid carcinoma (thyroid cancer), lymphoblastic leukemia, and myeloblastic leukemia.7

As a consequence of its small genome and non-enveloped structure, B19V is resistant to many procedures used to inactivate viruses. The virus is stable in lipid solvents (ether, chloroform) but can be inactivated by formalin, Β-propiolactone and oxidizing agents. Gamma irradiation will also inactivate B19V. Although it is not quite as resistant to heat as other parvoviruses, transmission of B19V by heat-treated (at 56 °C for 60 min) blood products has been documented.2

Hand washing and avoiding sharing food or drinks may partially prevent the spread of erythrovirus B19.6

References

  1. Desk Encyclopedia of Human and Medical Virology. Brian W. J. Mahy, Marc H. V. van Regenmortel
  2. Transfusion Microbiology. John A. J. Barbara, Fiona A. M. Regan, Marcela Contreras
  3. Practical Transfusion Medicine. Michael F. Murphy, Derwood H. Pamphilon
  4. Viruses and human disease. James H. Strauss, Ellen G. Strauss
  5. Infectious disease: pathogenesis, prevention, and case studies By Nandini Shetty, Julian W. 'Tang, Julie Andrews; 6. Clinical Infectious Disease. David Schlossberg
  6. HPV and Other Infectious Agents in Cancer by Hans Krueger, Gavin Stuart



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