Key learning points
- Parvovirus is a common infection in children.
- It is usually mild and self-limiting.
- Parvovirus can cause arthropathy, haematological or fetal complications in certain groups.
- Parvovirus causes ninety percent of aplastic crises in patients with chronic haemolytic anaemia.
- Contact or infection in pregnancy needs investigation.
Parvovirus, fifth disease, erythema infectiosum or ’slapped cheek’
Parvovirus B19 is a virus, most commonly affecting primary school age children. Sixty percent of adults will have been infected at some time in their lives, often without showing symptoms, and have developed immunity.1 The disease is not the same as parvovirus in pets.
Symptoms include 2,3
- prodromal non-specific flu-like illness
- fever
- red cheeks (most common in children), hence ‘slapped cheek’
- lace-like red rash, usually on the limbs and across the shoulders, which appears one to four days after the ‘slapped cheeks’ and may fluctuate in response to exercise, heat and sunlight, 4 it can be itchy in adults
- joint aches and pains - arthralgia and arthropathy (most common in adults)
- aplastic crises
The incubation period is four to twenty days (average fourteen days). Patients are infectious for seven days before the onset of the rash. Once the rash has appeared the infectivity drops dramatically.3 The virus is spread by close contact through droplet infection and occasionally via blood products.
Parvovirus can be clinically similar to rubella, measles and other childhood exanthems; it can only be reliably distinguished from rubella by laboratory tests.1 Serum is needed to detect parvovirus IgM, whereas mumps, measles and rubella IgM can be detected in saliva. (Salivary testing kits are available from the Health Protection Unit or microbiology laboratory.)
Figure 1: An image of a child with parvovirus demonstrating a red cheek.
Arthropathy and haematological complications1,2,4
Up to sixty percent of adults (more commonly women) exposed to parvovirus develop arthralgia, and can develop a symmetrical arthropathy, most commonly affecting the hands, wrists, knees and ankles. Eight percent of children with the infection have arthralgia. Joint symptoms usually resolve in a few days but some cases can persist for many months and mimic rheumatoid or juvenile arthritis.
Parvovirus infects dividing cells and can halt erythropoeisis for up to five days; there is therefore a risk of transient aplastic crises in patients with chronic haemolytic anaemias such as thalassaemia and sickle cell disease. More rarely, red cell aplasia or chronic anaemia may occur in patients with immunocompromise as a result of persistent infection.
Figure 2: A film showing aplastic anaemia in a patient who had a parvovirus infection.
Management
Most patients and contacts only need reassurance and possibly treatment of symptoms. However pregnant women, immunocompromised patients and those with haematological conditions need a medical assessment to consider further investigation.
Handwashing may help reduce transmission, but there is no need for exclusion from school or other activities as the pathognomic rash is immune-mediated and appears only when patients are no longer infectious.
Parvovirus and pregnancy1,5
Infection in the first twenty weeks of pregnancy leads to an increased risk of miscarriage. In weeks nine to twenty there is also a three percent risk of foetal hydrops. There is no evidence of associated congenital abnormalities.
Asymptomatic infection is as much a risk as symptomatic infection.
All pregnant women who have a non-vesicular rash, and even those in contact with someone with a rash, should be investigated for parvovirus and rubella infection, whatever their past history or serology. Investigation is recommended at any gestation, as even in later pregnancy a diagnosis may still be helpful.
Significant contact is defined as being in the same room for more than 15 minutes or face to face contact. Primary school teachers are at higher risk, those who are less than twenty one weeks pregnant and work in a school with a confirmed outbreak should be tested for immunity to parvovirus; if susceptible, on-going management should be discussed with the local health protection unit or a consultant microbiologist/virologist.
Parvovirus serology should be sent as soon as possible after contact or symptoms. Include as much detail as possible on the form. The sample will be tested for parvovirus and rubella IgG and IgM in parallel with the booking blood. Further investigation and management will depend on these results.
If IgM is detected, discuss confirmation of the diagnosis with the lab and take another sample immediately. Confirmed parvovirus infection in pregnancy requires referral to obstetrics for serial ultrasound scanning for hydrops.
References
- Health Protection Agency. General Information on Parvovirus 2008.
- Servey J T, Reamy B V, Hodge J. Clinical presentations of parvovirus B19 infection. Am Fam Physician. 2007; 75: 373-376.
- Health Protection Agency. Parvovirus B19 infection (information leaflet) 2005.
- Heegaard E D, Brown K E; Human Parvovirus B19. Clin Microbiol Rev. 2002; 15: 485-505
- Health Protection Agency. Rash illness in pregnancy. 2008.
Further reading
Author and reviewers competing interests: none declared.
Images: Wellcome.