Chickenpox, Parvovirus B19, Listeria Monocytogenes

Question 1

What is the cause of chickenpox, how is it transmitted

Answer 1

Varicella zoster (VZV, human herpesvirus 3). A DNA virus of the herpes virus that is highly contagious and transmitted by respiratory droplets and by direct personal contact with vesicle fluid or indirectly via fomites (skin cells, hair, clothing and bedding)

Question 2

How is primary chickenpox infection characterised

Answer 2

• Primary infection is characterised by fever, malaise and a pruritic rash that develops into crops of maculopapules (become vesicular and crust over before healing)

Question 3

Incubation period of VZV

Answer 3

Between 1-3 weeks. The disease is infectious 48 hours before the rash appears and continues to be infectious until the vesicles crust over (usually crust within 5 days)

Question 4

Incidence of chickenpox in the general population and in pregnancy

Answer 4

• Chickenpox (primary VZV) is a common childhood disease that usually causes a mild infection- over 90% of individuals over 15 years in the UK are seropositive for VZV IgG
• As such, although contact with chickenpox is common in pregnancy, primary VZV is uncommon- complicates 3 in 1000 pregnancies (more likely in women from tropical and subtropical areas)

Question 5

Chickenpox disease course

Answer 5

• Following primary infection, the virus remains dormant in the sensor nerve root ganglia but can be reactivated to cause a vesicular erythematous skin rash with a dermatomal distribution (Shingles)

Question 6

Complications of VZV infection in pregnancy

Answer 6

• Maternal- varicella pneumonitis, hepatitis, encephalitis
• Foetal: 1-2% Teratogenicity – in early pregnancy (< 20 wks) infection leads to foetal varicella syndrome in around 1% of pregnancies. Infection within 4 weeks of delivery (worst if within 5 days after or 2 days before maternal infection) leads to severe neonatal varicella infection

Question 7

What is congenital varicella syndrome, what are its consequences

Answer 7

Congenital varicella syndrome occurs in around 1% of cases of chickenpox in pregnancy. It occurs when infection is acquired in the first 28 weeks of gestation. Typical features include:
* FGR
* Microcephaly, hydrocephalus and learning disability
* Scars and significant skin changes located in specific dermatomes and limb hypoplasia (underdeveloped limbs)
* Cataracts and inflammation in the eye (chorioretinitis)

Question 8

Prevention of chickenpox in pregnancy

Answer 8

• Varicella vaccination prepregnancy or postpartum is an option that should be considered for women who are found to be seronegative for VZV IgG
• Universal serological antenatal testing is not recommended in the UK, seronegative women could be offered postpartum immunisation
• Women who are vaccinated postpartum can be reassured it is safe to breastfeed
• Live attenuated virus which offers protection for up to 20 years
• Women booking for antenatal care should be asked about previous chickenpox/shingles infection
• Women who have not had chickenpox, or are known to be seronegative for chickenpox, should be advised to avoid contact with chickenpox and shingles during pregnancy
• When contact occurs with chickenpox or shingles, a careful history must be taken to confirm the significance of the contact and the susceptibility of the patient
• Pregnant women with an uncertain or no previous history of chickenpox, or who come from tropical and subtropical countries, who have been exposed to infection should be tested for VZV IgG
• If the woman is not immune and has had significant exposure (ask about exposure, vesicle crusting etc.), they should be offered VZIG as soon as possible. VZIG is effective when given up to 10 days after contact.
• These women should be managed as potentially infectious from 8-28 days after exposure if they receive VZIG
• Should be isolated from other pregnant women if they develop a chickenpox rash
• A second dose of VZIG is required if a further exposure is reported and 3 weeks has elapsed since the last dose

Question 9

How is significant contact with chickenpox case defined

Answer 9

Contact in the same room for 15 minutes or more, face-to-face contact or contact in the setting of a large open ward

Question 10

Prognosis of chickenpox infection in adults

Answer 10

• There is an increased morbidity associated with varicella infection in adults, including pneumonia, hepatitis, and encephalitis. Rarely, it may result in death

Question 11

Management of pregnant women who develop a chickenpox rash

Answer 11

• Women who develop a chickenpox rash should immediately contact their GP
• Should avoid contact with potentially susceptible individuals e.g other pregnant women and neonates, until the lesions have crusted over (usually takes around 5 days)
• Symptomatic treatment and hygiene is advised to prevent secondary bacterial infection
• Oral acyclovir should be prescribed if they present within 24 hours of onset of the rash and if they are 20+0 weeks or beyond (can be prescribed before this also)- Can itself cause foetal anomalies
• IV acyclovir can be given in serious infection
• VZIG has no therapeutic benefit once chickenpox has developed and should therefore not be used

Question 12

When should hospital admission be considered in pregnant women with chickenpox

Answer 12

• A pregnant woman with chickenpox should present immediately if they develop respiratory symptoms or any other deterioration in condition
• A hospital assessment should be considered in a woman at high risk of severe or complicated chickenpox even in the absence of concerning symptoms or signs. E.g smoking, chronic lung disease, immunocompromised, in the second half of pregnancy
• Respiratory symptoms, neurological symptoms such as photophobia, seizures or drowsiness, a haemorrhagic rash or bleeding, or a dense rash with or without mucosal lesions are indicative of potentially life-threatening chickenpox
• Women who are admitted should be nursed in isolation from babies and other pregnant women

Question 13

How is timing and mode of delivery affected by chickenpox

Answer 13

• The timing and mode of delivery of the pregnant woman with chickenpox must be individualised.
• Ideally a minimum of 7 days should elapse between the onset of rash and delivery
• When epidural or spinal anaesthesia is undertaken in women with chickenpox, a site free of cutaneous lesions should be chosen for needle placement
• Spontaneous miscarriage risk does not appear to be increased if chickenpox occurs in the first trimester

Question 14

Management of congenital varicella syndrome

Answer 14

• Women who develop chickenpox in pregnancy should be referred to a foetal medicine specialist, at 16–20 weeks or 5 weeks after infection, for discussion and detailed ultrasound examination.
• Amniocentesis has a strong negative predictive value but a poor positive predictive value, therefore women should be counselled on risks vs benefits on amniocentesis for PCR
• Amniocentesis should not be performed before the skin lesions have completely healed
• If maternal infection occurs in the last 4 weeks of a woman’s pregnancy, there is a significant risk of CVS. A planned delivery should normally be avoided for at least 7 days after the onset of the maternal rash to allow for the passive transfer of antibodies from mother to child

Postnatal:
* A neonatologist should be informed of the birth of all babies born to women who have developed chickenpox. Arrange neonatal ophthalmic examination after birth
* If birth occurs within 7 days of the onset of the rash or the mother develops chickenpox within 7 days of delivery, the neonate should be given VZ Ig and monitored for signs of infection until 28 days after the onset of maternal infection
* If neonatal infection occurs, treat with acyclovir
* Women with chickenpox should be encouraged to breastfeed

Question 15

Summary chickenpox management

Answer 15

Question 16

What is parvovirus B19, what are the consequences of B19 infection in pregnancy

Answer 16

Parvovirus B19 is a small single-stranded DNA virus and is a member of the Parvoviridae family (erythrovirus). Pregnant women are at increased risk of potentially life-threatening complications from parvovirus.

Question 17

How is parvovirus transmitted

Answer 17

• The virus is usually transmitted by droplets spread through respiratory secretions and more rarely by vertical transplacental transmission from pregnant woman to the foetus.

Question 18

What is the incubation period for parvovirus B19, where is the infection targeted

Answer 18

• The virus targets rapidly growing erythroid progenitor cells which form red cells, found in bone marrow, foetal liver, umbilical cord and peripheral blood.
• The incubation period for the virus is around 14-21 days

Question 19

What is the incidence of parvovirus infection

Answer 19

• 60-70% of women of childbearing age have serological evidence of past infection
• Around 1-3% of susceptible pregnant women develop serologic evidence of infection during pregnancy, rising to over 10% in endemic periods
• Seasonal outbreaks of parvovirus B19 occur every 3-4 years in the UK, mainly in late winter and early spring

Question 20

When is the foetus most vulnerable to parvovirus infection

Answer 20

• Foetus is most vulnerable in the second trimester (low risk after 20 weeks)

Question 21

When is the foetus most vulnerable to parvovirus infection

Answer 21

• Foetus is most vulnerable in the second trimester (low risk after 20 weeks)

Question 22

Complications of parvovius B19 infection in pregnancy

Answer 22

• In the majority of cases of maternal infection the foetus is unaffected, however it can result in:

Non-immune hydrops fetalis:
* Infection of foetal erythroid progenitor cells in the bone marrow and liver may cause profound aplastic anaemia (shown on USS as high velocity in the foetal middle cerebral artery), hypoalbuminemia, HF (high output)
* Hydrops fetalis= abnormal accumulation of fluid in two or more foetal compartments- MOST COMMON manifestation of parvovirus B19 infection
* Diagnosed on USS- ascites, pleural or pericardial effusion, scalp oedema, polyhydramnios, subcutaneous oedema
* Occurs since there us increased extrahepatic and hepatic erythropoiesis- (portal HTN and hypoproteinaemia), high output HF
* Generally occurs 3-5 weeks after onset of maternal infection, in 3-11% of infection between 9-20 weeks gestation (causes foetal loss in 40-50% of cases)

Foetal death:
* The overall rate of foetal loss is 5-10%- may occur with or without evidence of hydrops fetalis
* Infection in the first 20 weeks increases risk

Maternal pre-eclampsia like syndrome:
* A development of maternal oedema associated with foetal hydrops (maternal signs reflect those present in the foetus).

Question 23

How is significant exposure to B19 defined

Answer 23

15 minutes in the same room, or face-to-face contact with someone that has the virus

Question 24

Presentation of parvovirus B19 infection

Answer 24

• Suspect infection in adults if they present with a history of contact with PB19 infection (usually in a child), or there is a known local outbreak
• The infectious period is up to 10 days before the onset of the rash
• May be asymptomatic
• Prodromal symptoms are more common in adults and may appear around a week after contact with the infection
• Self-limiting symmetrical polyarthropathy of the small joints is often the most common presenting symptom, occurring in 50% of adults (affects the joints of the hands, wrists, knees and ankles predominantly)
• The characteristic ‘slapped cheek’ (erythema infectiosum) rash seen in children may be absent in adults, who may develop a maculopapular rash on the trunk, back, limbs around 2-3 weeks after the first prodromal symptoms.

Question 25

Investigations for parvovirus B19 infection

Answer 25

• Contact the local virology, microbiology or infectious diseases department immediately for further advice

Urgent blood testing for:
* PVB19-specific IgM- If not detected, this excludes infection in the 4 weeks prior to the blood test. Infection cannot be excluded if the blood test is taken more than 4 weeks after the onset of rash or associated illness. If detected, this suggests a recent infection
* PCR for high-titre viral DNA for confirmation of diagnosis

After possible exposure to PVB19:
* Take bloods for IgG and IgM
* Positive for IgG and negative for IgM- indicates past infection (retesting not necessary)
* Negative for both- susceptible to infection. Repeat a blood test 1 month after last contact if she remains asymptomatic and earlier if she develops symptoms
* Positive for IgM (irrespective of IgG result)- indicates recent infection

Can identify characteristic intranuclear inclusions on histological samples or microscopy
Require urgent FBC and reticulocyte count

Question 26

Management of parvovirus B19 in pregnancy

Answer 26

• Assess whether, and when, there has been significant contact with any person with a potentially infectious rash or illness (before the onset of rash, if any).
• Contact the local virology, microbiology, or infectious diseases department immediately for further advice on what laboratory investigations and monitoring should be arranged:
• Will require rubella testing irrespective of the woman’s previous testing or immunisation status to rubella.
• Give advice on self-management strategies (condition is self-limiting)- use simple analgesia
• No need to stay off work if symptoms are controlled and known to be uninfected- infection is no longer contagious at the time of rash or when arthropathy develops
• Should avoid contact with other pregnant women if there is concern about ongoing infection
• Arrange an urgent referral to a specialist in foetal medicine for ongoing monitoring and management:
• Serial foetal USS and Doppler assessment to detect foetal anaemia (MCA), HF, hydrops fetalis. May start around 4 weeks after the onset of symptoms or at the estimated time of seroconversion (12 weeks)
• Should arrange admission for women with acute complications in pregnancy (severe or aplastic anaemia)

Question 27

Management of confirmed hydrops fetalis

Answer 27

Intravascular transfusion (increases survival rate)- always offer within the first 20 weeks, or expectant management (spontaneous resolution occurs in 50% with no long term sequalae)

Question 28

Definition and incidence of listeriosis in pregnancy

Answer 28

Listeriosis is predominantly a foodborne illness, with sporadic and outbreak-related cases tied to consumption of food contaminated with Listeria monocytogenes (aerobic, gram-positive bacillus). The incidence of listeriosis in pregnancy is approximately 13x higher than the general population.

Question 29

What are some food sources of listeria monocytogenes

Answer 29

soft cheese, milk, shrimp, rice salad and uncooked chicken

Question 30

Complications of listeriosis in pregnancy

Answer 30

• Maternal infection can lead to placental infection and, in turn, foetal septicaemia. The foetus may also be colonised by passage through the birth canal
• Foetal loss, preterm labour, neonatal sepsis, meningitis and death. In the mother, it can lead to maternal septicaemia or meningitis and occasionally the onset of labour may induce a fever

Question 31

Presentation of listeriosis in mother

Answer 31

• The classic pathology of listeriosis involves abscess formation, though maternal infection may be asymptomatic
• Infectious mononucleosis-like syndrome: malaise, chills, fever, pharyngitis, lymphadenopathy
• Influenza-like syndrome: fever, headaches, upper respiratory syndromes
• Typhoid-like syndromes: high spiking temperature, back pain
• Febrile gastroenteritis

Question 32

Presentation of listeriosis in the newborn

Answer 32

• Early onset listeriosis, within 2 days of birth, presents with signs of septicaemia and meningitis. Infected neonates are often delivered preterm, and would usually have acquired the infection from the placenta.
• Late onset listeriosis, which presents after 5 days with meningitis, is usually a result of infection during delivery.

Question 33

Prognosis of listeriosis in pregnancy

Answer 33

• 1 in 5 pregnancies complicated by listeriosis result in stillbirth or spontaneous abortion, 2/3 of surviving infants develop clinical neonatal listeriosis.
• Overall perinatal mortality rate of 29%

Question 34

Investigations for listeriosis

Answer 34

• L.monocytogenes is tested for in the mother by blood culture, rectovaginal culture and gram staining
• An amniocentesis sample can also be cultured and bacteria gram stained

Question 35

Management of listeriosis in pregnancy

Answer 35

• Typical treatment is by IV administration of ampicillin plus gentamcin
• In order to prevent infection, women should be encouraged to avoid soft cheeses, and not to re-heat leftover food