Parvovirus B19
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It has been suggested that this article or section be merged into Erythema infectiosum . (Discuss) |
| Erythrovirus | |
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| Electron micrograph of Parvoviruses in blood | |
| Virus classification | |
| Group: | Group II (ssDNA) |
| Family: | Parvoviridae |
| Genus: | Erythrovirus |
| Species: | Parvovirus B19 |
The B19 virus, generally referred to as parvovirus B19[1] or sometimes erythrovirus B19[2], was the first (and until 2005 the only) known human virus in the family of parvoviruses, genus erythrovirus. B19 virus causes a childhood rash called fifth disease or erythema infectiosum which is commonly called slapped cheek syndrome.[3][4]
The virus was discovered by chance in 1975 by Australian virologist Yvonne Cossart.[4][5] It gained its name because it was discovered in well B19 of a large series of petri dishes apparently numbered in this way.[4][6]
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[edit] Virology
Erythroviruses belong to the Parvoviridae family of small DNA viruses.[7] It is a non-enveloped, icosahedral virus that contains a single-stranded linear DNA genome. Approximately equal proportions of DNA of positive and negative sense are found in separate particles. At each end of the DNA molecule there are palindromic sequences which form "hairpin" loops. The hairpin at the 3' end serves as a primer for the DNA polymerase.[8] It is classified as erythrovirus because of its capability to invade red blood cell precursors in the bone marrow.
[edit] Transmission
The virus is primarily spread by infected respiratory droplets; blood-borne transmission, however, has been reported.[9] The secondary attack risk for exposed household persons is about 50%, and about half of that for classroom contacts.[4][10]
[edit] Infectivity
Symptoms begin some six days after exposure and last about a week. Infected patients with normal immune systems are contagious before becoming symptomatic, but probably not after then.[11] Individuals with B19 IgG antibodies are generally considered immune to recurrent infection, but reinfection is possible in a minority of cases.[12] About half of adults are B19-immune due to a past infection.
[edit] Epidemiology
A significant increase in the number of cases is seen every three to four years; the last epidemic year was 1998. Outbreaks can arise especially in nurseries and schools.
Parvovirus B19 causes an infection in humans only; cat and dog parvoviruses do not infect humans. In contrast with small animals, there is no vaccine available for human parvovirus B19.[13]
[edit] Role in disease
[edit] Fifth disease
Fifth disease or erythema infectiosum is only one of several expressions of Parvovirus B19. Any age may be affected, although it is most common in children aged six to ten years.
After being infected, patients usually develop the illness after an incubation period of four to fourteen days. The disease commences with fever and malaise while the virus is most abundant in the bloodstream, and patients are usually no longer infectious once the characteristic rash of this disease has appeared.[13]
Teenagers or young adults tend to develop the so called 'Papular Purpuric Gloves and Socks Syndrome'.[13] Unlike young children, these patients may be infectious with this rash.[citation needed]
The rash of fifth disease is typically described as "slapped cheeks," with erythema across the cheeks and sparing the nasolabial folds, forehead, and mouth. Because of this rash, fifth disease is sometimes called 'slapped cheek syndrome'.[4] Fifth disease is also known for "lace-like" rashes on the arms, legs, torso, and back. These rashes can last for up to 5 weeks and are worse after sun exposure, exercise, or hot baths.[citation needed]
[edit] AIDS
Parvovirus B19 is a frequently overlooked cause of chronic anemia in individuals who have AIDS. Treatment with erythropoetin or intravenous immunoglobulin have been helpful in some patients. The parvovirus infection may trigger an inflammatory reaction in AIDS patients who have just begun antiretroviral therapy.[14]
[edit] Arthritis
In adults (and perhaps some children), parvovirus B19 can lead to a seronegative arthritis which is usually easily controlled with analgesics. Women are approximately twice as likely as men to experience arthritis after parvovirus infection. Possibly up to 15% of all new cases of arthritis are due to parvovirus, and a history of recent contact with a patient and positive serology generally confirms the diagnosis.[11] This arthritis does not progress to other forms of arthritis. Typically joint symptoms last 1–3 weeks, but in 10-20% of those affected, it may last weeks to months.[4][13]
[edit] Aplastic crisis
Although most patients have an arrest of erythropoiesis (production of red blood cells) during parvovirus infection, it is most dangerous in patients who have sickle cell anemia or hereditary spherocytosis, and are therefore heavily dependent on erythropoeisis due to the reduced lifespan of the red cells. This is termed "aplastic crisis" (also called reticulocytopenia). It is treated with blood transfusion.[4][13]
[edit] Hydrops fetalis
Parvovirus infection in pregnant women is associated with hydrops fetalis due to severe fetal anemia, sometimes leading to miscarriage or stillbirth.[13][15] The risk of fetal loss is about 10% if infection occurs before pregnancy week 20 (esp. between weeks 14-20), but minimal after then. Routine screening of the antenatal sample would enable the pregnant mother to determine the risk of infection. Knowledge of her status would allow the mother to avoid the risk of infection. The risk to the fetus will be reduced with correct diagnosis of the anemia (by ultrasound scans) and treatment (by blood transfusions). There is no evidence to suggest that Parvovirus B19 leads to developmental abnormalities in childhood.[citation needed]
[edit] See also
[edit] References
- ^ Servey JT, Reamy BV, Hodge J (February 2007). "Clinical presentations of parvovirus B19 infection". Am Fam Physician 75 (3): 373–6. PMID 17304869.
- ^ Kahn JS, Kesebir D, Cotmore SF, et al. (July 2008). "Seroepidemiology of human bocavirus defined using recombinant virus-like particles". J. Infect. Dis. 198 (1): 41–50. doi:. PMID 18491974.
- ^ Vafaie J, Schwartz RA (2004). "Parvovirus B19 infections". Int J Dermatol 43 (10): 747–9. doi:. PMID 15485533.
- ^ a b c d e f g Sabella C, Goldfarb J (October 1999). "[www.aafp.org/afp/991001ap/1455.html Parvovirus B19 infections]". Am Fam Physician 60 (5): 1455–60. PMID 10524489. www.aafp.org/afp/991001ap/1455.html. Retrieved 2009-11-06.
- ^ Heegaard ED, Brown KE (2002). "Human parvovirus B19". Clin. Microbiol. Rev. 15 (3): 485–505. doi:. PMID 12097253. PMC 118081. http://cmr.asm.org/cgi/pmidlookup?view=long&pmid=12097253.
- ^ Cossart YE, Field AM, Cant B, Widdows D (1975). "Parvovirus-like particles in human sera". Lancet 1 (7898): 72–3. doi:. PMID 46024.
- ^ Brown KE (2004). "Variants of B19". Dev Biol (Basel) 118: 71–7. PMID 15645675.
- ^ G. Siegl and P. Cassinotti, Parvoviruses Chapter 14, Topley and Wison's Microbiology and Microbial Infections, Vol. 1, Virology, 1998 pp. 261-280
- ^ Pattison JR, Patou G (1996). Parvoviruses. In: Barron's Medical Microbiology (Barron S et al., eds.) (4th ed.). Univ of Texas Medical Branch. ISBN 0-9631172-1-1.
- ^ Young NS, Brown KE (February 2004). "Parvovirus B19". N Engl J Med 350 (6): 586–97. doi:. PMID 14762186.
- ^ a b Corcoran A, Doyle S (2004). "Advances in the biology, diagnosis and host-pathogen interactions of parvovirus B19". J Med Microbiol 53 (Pt 6): 459–75. doi:. PMID 15150324.
- ^ Lehmann HW, von Landenberg P, Modrow S (2003). "Parvovirus B19 infection and autoimmune disease". Autoimmun Rev 2 (4): 218–23. doi:. PMID 12848949.
- ^ a b c d e f Servey JT, Reamy BV, Hodge J (February 2007). "[www.aafp.org/afp/20070201/373.html Clinical presentations of parvovirus B19 infection]". Am Fam Physician 75 (3): 373–6. www.aafp.org/afp/20070201/373.html. Retrieved 2009-11-06. PMID 17304869
- ^ Doldan Silvero AM, Acevedo-Gadea CR, Pantanowitz L, Dezube BJ, Johari V (June 4, 2009). "Images in HIV/AIDS. Unsuspected parvovirus B19 infection in a person with AIDS". The AIDS Reader 19 (6): 225–7. http://www.consultantlive.com/aids/article/1145619/1419436. Retrieved 2009-11-06. PMID 19642240
- ^ Ergaz Z, Ornoy A (May 2006). "Parvovirus B19 in pregnancy". Reprod. Toxicol. 21 (4): 421–35. doi:. PMID 16580942. http://linkinghub.elsevier.com/retrieve/pii/S0890-6238(05)00025-0.
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