Parvovirus B19
Encyclopedia
The B19 virus, generally referred to as parvovirus B19 or sometimes erythrovirus B19, was the first (and until 2005 the only) known human virus in the family
of parvovirus
es, genus
erythrovirus. B19 virus causes a childhood rash
called fifth disease
or erythema infectiosum which is commonly called slapped cheek syndrome.
The virus was discovered by chance in 1975 by Australia
n virologist Yvonne Cossart. It gained its name because it was discovered in well B19 of a large series of petri dish
es labelled in this way.
family of small DNA viruses. 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. It is classified as erythrovirus because of its capability to invade red blood cell
precursors in the bone marrow
.
droplets; blood-borne transmission, however, has been reported. The secondary attack risk for exposed household persons is about 50%, and about half of that for classroom contacts.
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. There is no vaccine available for human parvovirus B19, though attempts have been made to develop one.
However, there is a vaccine available for parvovirus that infects small mammals.
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, it is so named, because it was the fifth pink-red infectious rash to be described by physicians.
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.
Teenagers or young adults may develop the so called 'Papular Purpuric Gloves and Socks Syndrome'. Unlike young children, these patients may be infectious with this rash.
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'. 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.
. It is frequently overlooked. 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.
which is usually easily controlled with analgesic
s. 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. 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.
(production of red blood cell
s) 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
.
due to severe fetal anemia
, sometimes leading to miscarriage
or stillbirth
. 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 some evidence that intrauterine Parvovirus B19 infection leads to developmental abnormalities in childhood.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of parvovirus
Parvovirus
Parvovirus, often truncated to "parvo", is both the common name in English casually applied to all the viruses in the Parvoviridae taxonomic family, and also the taxonomic name of the Parvovirus genus within the Parvoviridae family...
es, genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
erythrovirus. B19 virus causes a childhood rash
Exanthem
An exanthem is a widespread rash usually occurring in children. Exanthems can be caused by toxins or drugs, microorganisms, or can result from autoimmune disease.It can be contrasted with an enanthem.-Types:...
called fifth disease
Fifth disease
Erythema infectiosum or fifth disease is one of several possible manifestations of infection by erythrovirus, previously called parvovirus B19. The disease is also referred to as slapped cheek syndrome, slapcheek, slap face or slapped face. In Japan the disease is called 'apple sickness' or...
or erythema infectiosum which is commonly called slapped cheek syndrome.
The virus was discovered by chance in 1975 by Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n virologist Yvonne Cossart. It gained its name because it was discovered in well B19 of a large series of petri dish
Petri dish
A Petri dish is a shallow glass or plastic cylindrical lidded dish that biologists use to culture cells or small moss plants. It was named after German bacteriologist Julius Richard Petri, who invented it when working as an assistant to Robert Koch...
es labelled in this way.
Virology
Erythroviruses belong to the ParvoviridaeParvoviridae
The Parvoviridae family includes the smallest known viruses, and some of the most environmentally resistant. They were discovered during the 1960s and affect vertebrates and insects...
family of small DNA viruses. 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
Sense (molecular biology)
In molecular biology and genetics, sense is a concept used to compare the polarity of nucleic acid molecules, such as DNA or RNA, to other nucleic acid molecules...
serves as a primer for the DNA polymerase. It is classified as erythrovirus because of its capability to invade red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
precursors in the bone marrow
Bone marrow
Bone marrow is the flexible tissue found in the interior of bones. In humans, bone marrow in large bones produces new blood cells. On average, bone marrow constitutes 4% of the total body mass of humans; in adults weighing 65 kg , bone marrow accounts for approximately 2.6 kg...
.
Transmission
The virus is primarily spread by infected respiratoryRespiration (physiology)
'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...
droplets; blood-borne transmission, however, has been reported. The secondary attack risk for exposed household persons is about 50%, and about half of that for classroom contacts.
Infectivity
Symptoms begin some six days after exposure (between 4 and 21 days according to the article about fifth disease and 4 to 28 days, with the average being 16 to 17 days according to this article http://kidshealth.org/parent/infections/skin/fifth.html) and last about a week. Infected patients with normal immune systems are contagious before becoming symptomatic, but probably not after then. Individuals with B19 IgG antibodies are generally considered immune to recurrent infection, but reinfection is possible in a minority of cases. About half of adults are B19-immune due to a past infection.Epidemiology
A significant increase in the number of cases is seen every three to four years; the last epidemicEpidemic
In epidemiology, an epidemic , occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience...
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. There is no vaccine available for human parvovirus B19, though attempts have been made to develop one.
However, there is a vaccine available for parvovirus that infects small mammals.
Role in disease
Fifth disease
Fifth diseaseFifth disease
Erythema infectiosum or fifth disease is one of several possible manifestations of infection by erythrovirus, previously called parvovirus B19. The disease is also referred to as slapped cheek syndrome, slapcheek, slap face or slapped face. In Japan the disease is called 'apple sickness' or...
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, it is so named, because it was the fifth pink-red infectious rash to be described by physicians.
After being infected, patients usually develop the illness after an incubation period
Incubation period
Incubation period is the time elapsed between exposure to a pathogenic organism, a chemical or radiation, and when symptoms and signs are first apparent...
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.
Teenagers or young adults may develop the so called 'Papular Purpuric Gloves and Socks Syndrome'. Unlike young children, these patients may be infectious with this rash.
AIDS
Parvovirus B19 is a cause of chronic anemia in individuals who have AIDSAIDS
Acquired immune deficiency syndrome or acquired immunodeficiency syndrome is a disease of the human immune system caused by the human immunodeficiency virus...
. It is frequently overlooked. 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.
Arthritis
In adults (and perhaps some children), parvovirus B19 can lead to a seronegative arthritisSeronegative arthritis
A seronegative arthritis is an arthritis that is distinguished from rheumatoid arthritis due the absence of rheumatoid factor .-Contrasting with rheumatoid arthritis:...
which is usually easily controlled with analgesic
Analgesic
An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....
s. 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
Serology
Serology is the scientific study of blood serum and other bodily fluids. In practice, the term usually refers to the diagnostic identification of antibodies in the serum...
generally confirms the diagnosis. 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.
Aplastic crisis
Although most patients have an arrest of erythropoiesisErythropoiesis
Erythropoiesis is the process by which red blood cells are produced. It is stimulated by decreased O2 in circulation, which is detected by the kidneys, which then secrete the hormone erythropoietin...
(production of red blood cell
Red blood cell
Red blood cells are the most common type of blood cell and the vertebrate organism's principal means of delivering oxygen to the body tissues via the blood flow through the circulatory system...
s) during parvovirus infection, it is most dangerous in patients who have sickle cell anemia or hereditary spherocytosis
Hereditary spherocytosis
Hereditary spherocytosis is a genetically-transmitted form of spherocytosis, an auto-hemolytic anemia characterized by the production of red blood cells that are sphere-shaped rather than bi-concave disk shaped , and therefore more prone to hemolysis.-Symptoms:As in non-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
Reticulocytopenia
Reticulocytopenia, or "aplastic crisis", is the medical term for an abnormal decrease of reticulocytes in the body. Reticulocytopenia can originate from congenital hemolytic anemia, especially when exacerbated by Parvovirus B19 infection...
). It is treated with blood transfusion
Blood transfusion
Blood transfusion is the process of receiving blood products into one's circulation intravenously. Transfusions are used in a variety of medical conditions to replace lost components of the blood...
.
Hydrops fetalis
Parvovirus infection in pregnant women is associated with hydrops fetalisHydrops fetalis
Hydrops fetalis is a condition in the fetus characterized by an accumulation of fluid, or edema, in at least two fetal compartments. By comparison, hydrops allantois or hydrops amnion are an accumulation of excessive fluid in the allantoic or amniotic space respectively.-Presentation:Locations can...
due to severe fetal anemia
Anemia
Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...
, sometimes leading to miscarriage
Miscarriage
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...
or stillbirth
Stillbirth
A stillbirth occurs when a fetus has died in the uterus. The Australian definition specifies that fetal death is termed a stillbirth after 20 weeks gestation or the fetus weighs more than . Once the fetus has died the mother still has contractions and remains undelivered. The term is often used in...
. 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
Obstetric ultrasonography
Obstetric sonography is the application of medical ultrasonography to obstetrics, in which sonography is used to visualize the embryo or foetus in its mother's uterus...
scans) and treatment (by blood transfusions). There is some evidence that intrauterine Parvovirus B19 infection leads to developmental abnormalities in childhood.