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Parvovirus (Slapped Cheek, B19 or Fifth Disease)

What is Parvovirus B19 (Human Parvovirus)?
Parvovirus B19 is a virus that commonly infects children and is usually transmitted by coughing and sneezing. School
teachers, child day–care workers, and mothers of young children are particularly likely to be exposed to this virus.
Parvovirus B19 is also known as ‘slapped cheek syndrome’ or ‘fifth disease’. The human virus, parvovirus B19 is NOT the
same parvovirus that vets may be concerned about in pets.

What are the symptoms of Parvovirus B19?
Parvovirus commonly causes a slight temperature, headache, and mild cold-like symptoms, such as a stuffy or runny nose.
These symptoms pass, and the illness seems to be gone until a rash appears a few days later.
The bright red rash usually begins on the face, which can resemble a slapped cheek appearance. Several days later, the
rash spreads and lighter red blotches extend down the body, arms, and legs. The rash usually does not appear on the
palms of the hands or soles of the feet. Children under 10 years old are the most likely to get the rash. Older children and
adults sometimes complain that the rash itches, but most children with a rash do not look sick and no longer have a fever. It
may take 1 to 3 weeks for the rash to completely clear. During that time, it may seem to worsen until it finally fades away
entirely.

Other symptoms that sometimes occur include swollen glands, red eyes, sore throat, diarrhoea, and rarely, rashes that look
like blisters or bruises. In rare cases, the infection may be followed by joint swelling or pain, often in the hands, wrists, knees,
or ankles. These symptoms are more common in adult women than in men. They usually last 2 - 4 weeks but may persist
for several months. A person with parvovirus infection is most likely to pass on the virus to others, before the rash appears
— either between being infected themselves and the onset of symptoms, or when experiencing only mild respiratory
symptoms, which can be anytime from 4 to 28 days following infection.

The rash is the result of an immune system reaction that occurs after the infection has passed, so children usually aren’t
contagious once it appears. Therefore infection with human parvovirus may have occurred earlier than you think. It is
important to note that many people with Human Parvovirus show no symptoms at all.

If you are concerned you may have caught parvovirus, there is no strong evidence to support being absent from work. This
is because by the time either the rash is present or a blood test has confirmed the presence of the infection, the period of
infectivity will have already occurred. However, if you feel unwell, you may choose to do so.

What happens if I think I may have been in contact with human parvovirus?
Approximately 50 - 60% of adults have been infected with parvovirus at some time in the past and you are therefore immune
to further infection.
If you think that you have been in contact with the parvovirus infection, or if you have a rash, you should report this to your
midwife (or doctor) as you will need to have a blood test. Contact is being in the same room as an infected person for more
than 15 minutes, or face-to-face contact. The main risk of infection is from household contacts or prolonged occupational
contact.
The blood test will tell if:
- You have had the parvovirus infection before and are now immune, so you are not at risk of infection.
- You currently have the infection.
- You have not had parvovirus before and may be able to catch the infection.

Parvovirus B19 and pregnancy
Parvovirus affects about 1 in 400 pregnancies. You are at increased risk if you catch the infection when you are between 4
and 20 weeks pregnant. Under 4 weeks, there is no transmission of the virus to the baby and over 20 weeks there is a much
lower risk.
In cases where mothers do catch the virus, 9 out of 10 babies will remain unaffected, however 1 in every 10 babies might go
on to suffer from anaemia (having a reduced level of red blood cells). If this is not monitored or remains untreated, this can
cause serious harm to those babies. Severe anaemia can lead to a condition known as fetal hydrops, which very rarely can
lead to the baby dying. Fortunately, this tragic outcome is seen in only 3 in 100 babies of infected mothers and can be
reduced by closely monitoring the baby for signs of fetal anaemia and treating as necessary. Parvovirus is not known to
cause congenital abnormalities.

What happens if I get parvovirus infection whilst pregnant?

If the results of your blood test confirm that you have the infection, your pregnancy will be monitored very closely. You will
be referred to the obstetric team at the hospital and you will have frequent ultrasound scans over several weeks. The
frequency of these scans will depend upon the stage of pregnancy and the findings at each scan.
If the baby shows signs of anaemia, you would be referred to the Fetal Medicine Unit in Southampton. Very rarely, some
babies require an intrauterine blood transfusion. This is a process where blood is given to the baby while it is still inside the
womb. This would be managed by this specialist unit.

If I have had a blood test for parvovirus, how soon can I expect a result?
If your Midwife or Doctor has taken a blood test for parvovirus, the result should be available within 7 - 10 working days.
Your Midwife, or Doctor, should contact you with the result as soon as they receive it.
If your blood test demonstrates antibodies to parvovirus in a sample taken before your presumed exposure date (such as
from a blood sample taken at booking), it indicates that you were immune before the exposure.
If your blood test shows that you are parvovirus antibody negative, you are susceptible to the infection. This means that you
will be required to be re-tested in 4 weeks’ time to see if you have developed antibodies to the virus.
If your initial or follow-up blood test demonstrated the presence of parvovirus antibodies of recent origin, or detectable virus,
it means that you have been recently infected and your baby is at risk of infection. The laboratory testing your blood will
inform an obstetrician as soon as the result is confirmed and you will be promptly referred for further follow-up.
If infection is strongly suspected, there may be some cases in which women may be referred for monitoring with ultrasound
scanning before the result of the blood test in order to check the well-being of your baby at the soonest available
opportunity.

Further information
National Institute for Health and Clinical Excellence (NICE)

This Irish website contains a wealth of information about parvovirus
Patient UK website

Health Protection Agency