Parvovirus B19 Exposure in Pregnancy (593)

Community midwives, midwives working in maternity triage, GPs and other primary care staff should be aware of the significance of parvovirus infection in pregnancy, and be able to advise pregnant women on appropriate investigation and follow up.

Any staff member performing testing for parvovirus infection should ensure that appropriate follow up arrangements for reviewing results are made, and appropriate onward referral made in the event of a resulting showing active or recent parvovirus infection.

Medical staff working in secondary care maternity services should be aware of the significance of parvovirus infection in pregnancy, and be able to advise pregnant women on appropriate investigation and follow up. Senior medical staff, at middle-grade and consultant level should understand how to interpret ultrasound studies assessing fetal wellbeing in the event of parvovirus infection in pregnancy and be familiar with the process of onward referral in the event of suspicion of fetal anaemia or hydrops.

Pregnant women with suspected parvovirus infection should be advised to attend primary care in the first instance, to reduce the risk of infection to other susceptible adults.

If a pregnant woman attends maternity triage with clinical features of parvovirus infection, or attends unannounced seeking care following contact with active parvovirus infection, they should be placed in a segregated area to avoid exposing other susceptible adults to the risk of infection.

Investigation

• Confirm gestation of pregnancy
• Enquire as to date of onset of illness, clinical features and type and distribution of any rash
• Enquire as to previous history of infection and antibody testing
• Enquire as to recent travel history, including dates and location
• Enquire as to any contact with any person with a rash illness, or recent travel
• Enquire as to the present of other comorbidities including immunosuppression, or a history of haemolytic anaemia (e.g. sickle cell disease, thalassaemia, hereditary spherocytosis)

Diagnosis

Take blood as soon as possible for parovirus IgM and IgG. If a rash has occurred, blood samples should be taken the following day following appearance of the rash. Note that the woman is pregnant and gestation on the clinical request.

If previous immunity to parvovirus is confirmed, usually by testing samples taken at the booking appointment, an alternative cause for the symptoms should be sought, as confirmed immunity is lifelong and further parvovirus infection cannot occur.

If the woman is parvovirus naive, current samples will be tested to ascertain if there are signs of ongoing infection, or if seroconversion (and therefore, infection with parvovirus at an earlier gestation) has occurred.

For patients who are immunocompromised, or those at risk of aplastic anaemia, a full blood count and reticulocyte count should be taken at the time of taking the parvovirus tests.

A lack of IgM, excludes current and previous parvovirus infection within the last 4 weeks before the sample was takenⁱⁱ,and excludes parvovirus as a cause of the symptoms. An alternative diagnosis should be sought.

Management

Paracetamol can be used for symptom relief.

The infected woman with a rash can be reassured that they are no longer infectious as the disease is no longer contagious at the onset of the rash.  

Urgent advice from the local haematology service should be sought for women with a history of haemolytic anaemia, as infection with parvovirus can lead to aplastic crisis.

Women at risk of aplastic crisis presenting with symptoms of breathlessness, light-headedness, lethargy or confusion, should be admitted to the antenatal ward for urgent investigation.

Confirmed parvovirus infection in pregnant womem should be referred to secondary maternity services for follow up. An ultrasound scan to perform Middle Cerebral Artery Dopplers to ascertain peak systolic velocity (MCA- PSV) and review by the named Obstetric Consultant should be undertaken as soon as possible.

Middle Cerebral Artery Dopplers should be performed fortnightly for 12 weeks after infection. In the event of diagnosing fetal hydrops, or finding a Middle Cerebral Artery Peak Systolic Velocity > 1.5 MOM, urgent referral to the Fetal Medicine Unit at the QUEH should be arranged. The appropriate online referral form should be completed, and the unit telephoned on ext 64339 (0141 232 4339) to inform them of the urgent referral.

Pregnant women with suspected parvovirus infection should be advised to attend primary care in the first instance, to reduce the risk of infection to other susceptible adults.

Investigation

• Confirm gestation of pregnancy
• Enquire as to whether the infection has been confirmed in the contact person
• Enquire as to when, where and for how long contact took place.
• Enquire as to previous history of parvovirus infection and antibody testing
• Enquire as to any history of recent illness
• Enquire as to the present of other comorbidities, specifically whether there is a history of immunosuppression or haemolytic anaemia

Patients presenting to maternity services with suspected parvovirus exposure for further investigation should be assessed in a segregated area, ideally a single room, and away from other patients pending their test result.

Diagnosis

Take blood as soon as possible for parovirus IgM and IgG. If a rash has occurred, blood samples should be taken the following day following appearance of the rash. Note that the woman is pregnant and gestation on the clinical request.

If previous immunity to parvovirus is confirmed, no further action is required. Immunity is lifelong and the pregnant woman can be reassured that they are not at risk of contracting parvovirus infection.  

If the woman is parvovirus naive, current samples will be tested to ascertain if there are signs of ongoing infection, or if seroconversion (and therefore, infection with parvovirus at an earlier gestation) has occurred.

Women with chronic haemolytic anaemia, at risk of parvovirus infection, should be advised to contact maternity services if they experience symptoms associated with aplastic crisis: breathlessness, light-headedness, lethargy or confusion.

Management

Confirmed Parvovirus Infection After Initial Exposure

Confirmed parvovirus infection in pregnant women should be referred to secondary maternity services for follow up. An ultrasound scan to perform Middle Cerebral Artery Dopplers and review by the named Obstetric Consultant should be undertaken as soon as possible.

Middle Cerebral Artery Dopplers should be performed fortnightly for 12 weeks after infection. In the event of diagnosing fetal hydrops, or finding a Middle Cerebral Artery Peak Systolic Velocity > 1.5 MOM, urgent referral to the Fetal Medicine Unit at the QUEH should be arranged. The appropriate online referral form should be completed, and the unit telephoned on ext 64339 (0141 232 4339) to inform them of the referral.

Perform fortnightly MCA Dopplers until 12 of weeks since infection. For patients who pose a risk of transmission to susceptible pregnant women (< 21 days since the exposure) they should be advised to take respiratory precautions when attending for ultrasound scan, and wait in a segregated area for their appointment.

No Evidence of Current Parvovirus Infection After Initial Exposure

The pregnant women should be advised that they remain at risk of contractive parvovirus infection, and to contact maternity services for advice if further exposure occurs.

A repeat blood sample for parvovirus IgM and IgG should be taken 4 weeks from the initial exposure.

If this shows evidence of seroconversion, manage as for “confirmed parvovirus infection after initial exposure”

• Transmission of parvovirus to susceptible adults generally occurs at low rates
• The greatest risk is in the home, where prolonged close contact is most likely to occur, and the risk of transmission in this circumstances is 50%
• Pregnant women who are susceptible to parvovirus infection who remain at occupational risk should discuss this with their employer, and be signposted to Guidance for control of Parvovirus B19 infection in healthcare settings and the community. Journal of Public Health, 1999 (Crowcroft et al)
• Parvovirus is spread by respiratory droplets, and respiratory precautions reduce the risk of infection.