Parvovirus B19 The Parvoviridae family includes a large number of small, genetically-compact DNA viruses known collectively as parvoviruses. Parvovirus B19 was the first pathogenic human parvovirus to be discovered and it is best known for causing the childhood illness called fifth disease.
Aside from a characteristic rash, which is seen in both pediatric and adult patients, parvovirus B19 also causes fever, headaches, sore throat, arthralgias and anemia.In healthy individuals, this anemia is mild and of short duration, but in individuals with weakened immune systems the resulting anemia can be severe and long-lasting. It is particularly dangerous to pregnant women during mid-trimester, since it can cause hydrops fetalis, severe fetal anemia and possibly lead to miscarriage or stillbirth. Parvovirus B19 spreads through respiratory secretions (such as saliva, sputum, or nasal mucus) when an infected person coughs or sneezes. It is highly contagious and a significant increase in the number of cases is seen every three to four years. Outbreaks are common, especially in nurseries and schools where both children and pregnant woman are at risk.
PARVOVIRUS B19 INFECTION CYCLE
Parvovirus B19
Bone marrow
Dissemination
Lungs
Heart
Endothelium
Liver
Joint
Gut
Kidney
Parvo B19 is transmitted by aerosol inhalation and the main target cells are erythroid progenitor cells in the bone marrow. Source: Immunopaedia.org
DIAGNOSIS Serologic testing has proven to be extremely useful and IgM antibodies can be detected approximately 10 days after the infection for about 30-60 days. The detection of an acute infection by IgM testing is critical to prevent outbreaks, and detection of IgG indicates the immune status of an individual (which is particularly important for pregnant women). Human B19 encodes a number of nonstructural proteins, including the major protein, NS1, and two structural proteins, VP1 and VP2. During an acute infection, B19-specific antibodies to both linear and conformational epitopes are produced against VP1 and VP2. Specifically, IgG antibodies are formed against the linear epitopes of the C-terminal end of VP1 early in infection. These antibodies remain for about 6-12 months after which they significantly decline. In contrast, antibodies to the linear epitopes at the N-terminal end of VP1 and the entire VP2 protein are detectable for life. IgM/IgG assays for B19 usually include detection of both the VP1 C-terminal (IgM response) and VP1 N-terminal and VP2 proteins (IgG response). In addition, detection of the B19 NS1 can be used as a supplement in case of borderline results by VP2.
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ToRCH & Childhood Diseases- Reagents for Assay Development
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