1. What is the causative agent, how does it enter the body and
how does it spread a) within the body and b) from person to
Parvovirus B19 belongs to the family of viruses known as the
These are characterized by having a small single-stranded DNA genome.
Parvovirus B19 belongs to the
genus within the subfamily
(and is therefore sometimes referred to as ‘erythrovirus’).
The suffix ‘B19’ is somewhat spurious, arising from the coding of the par-
ticular serum in which this virus was first identified, that is there are no
parvovirus A or B1–18 viruses. There are, however, three recognized
genotypes of B19 that differ slightly in their DNA sequence but behave
similarly in terms of the clinical consequences of infection.
Entry and spread within the body
Infection is acquired via the respiratory route. About 6 days after infection,
virus is found within the bloodstream, that is there is a viremic phase,
which lasts about 6 days.
Spread from person to person
About 1 week after infection, at the time of the
, virus is detectable
within the throat, and is shed from the respiratory tract, which represents
the common route of spread. However, there is also a possibility of trans-
mission via blood and blood products if blood donation is made at this
stage of infection. Virus in the maternal bloodstream will also gain access
to, and may cross, the placenta, giving rise to fetal infection
A 25-year-old teacher, who was 12 weeks pregnant, went
to see her doctor as she had developed an extensive
rash on her face, trunk, and limbs
(Figure 1). She was also feeling feverish, and had noticed
some aching in her wrists.
A blood sample was sent to the laboratory, and the
following results were received: rubella
-negative; parvovirus B19 IgM-positive; parvovirus B19
The unequivocal interpretation of these results was
that the patient was suffering from an acute infection with
© Lydyard, Peter; Cole, Michael; Holton, John; Irving, Will; Porakishvili, Nino; Venkatesan, Pradhib; Ward, Kate, Jan 01, 201
Garland Science, Hoboken, ISBN: 9780203856871