Parvovirus B19

Question 1

What are the host cell range for B19?

Answer 1

Erythroblasts
Megakaryocytes
Endothelial cells
Foetal myocardial cells
Foetal liver

Question 2

What is the receptor for B19?

Answer 2

Blood group P antigen

Question 3

Seroprevalence of B19 in UK?

Answer 3

50%

Question 4

What are three possible transmission routes for B19?

Answer 4

Droplet secretions
Transplacentally
Blood transfusion

Question 5

Describe slapped cheek symptoms

Answer 5

Prodromal illness 2-5 days before rash

Rash on face followed by limbs

Rash usually disappears after 7-10 days but can reoccur over 1-3 weeks

Question 6

Describe transient aplastic crisis, and what is the % caused by B19 in red cell diseases?

Answer 6

Fall in haemoglobin

Disappearance of reticulocytes

Absence of RBV precursors in bone marrow

90%

Question 7

Treatment for B19 induced transient aplastic crisis

Answer 7

Blood transfusion

Question 8

Symptoms of B19 infection in Immunosuppressed patients

Answer 8

Chronic anaemia

Allograft rejection

Worsening of neoplastic disease

Question 9

In which infection would you find giant probormoblasts in bone marrow?

Answer 9

B19

Question 10

What level of DNA is used to differentiate past from recent B19 infection?

Answer 10

> 10^4 IU/ml recent and less than indicates past infection

Question 11

What viral target does the B19 avidity test use?

Answer 11

VP1

Question 12

Treatment of B19 in Immunosuppressed patients?

Answer 12

Reduction of immunosuppression

IVIG - 400 mg/kg for 5 days

Question 13

Treatment of B19 encephalitis

Answer 13

IVIG and steroids

Question 14

Risk of B19 infection and foetal outcomes by gestation

Answer 14

Infection

<4 weeks = 0%
5-16 weeks = 15%
>16 weeks = 25-70% (increasing with gestation)

Adverse forms events

Under 20 weeks = 9% excess foetal loss, 3% hydrops (50% fatal without treatment)

Over 20 weeks = <1% (can’t find any evidence for this)

Question 15

How long after infection do symptoms of B19 in foetus occur?

Answer 15

3-5 weeks but can be longer

Question 16

Confirmation of B19 in first 20 weeks of pregnancy

Answer 16

IgM positive confirmed with evidence of seroconversion or high DNA

Question 17

What is more likely to cause congenital B19, symptomatic or asymptomatic infection

Answer 17

Equal

Question 18

Follow up for B19 infection in pregnancy

Answer 18

Confirmation of diagnosis

Referral to foetal medicine for Doppler and possible intrauterine infection

Question 19

Reasons why B19 hydrops occurs more often in the second trimester

Answer 19

High number of RBCs in the liver and short RBC lifespan

Immune immaturity

Question 20

Attack rate of B19 in households

Answer 20

50%

Question 21

At risk groups for B19 exposure

Answer 21

Pregnant woken up to 20 weeks gestation

Patients with haemoglobinopathies

Immunocompromised patients

Question 22

Definition of B19 outbreak in school

Answer 22

2 cases in same year or 3 case in the same school within 3 weeks