Microbiology - viral infections in pregnancy

Question 1

How many people experience reactivation of VZV (shingles) in their lifetime?

Answer 1

30-50%

Question 2

How does the epidemiology of primary VZV change depending on climates?

Answer 2

Temperate climates primary VZV mainly in childhood, 95% adult are immune

More tropical climates (sri lanka, carribean, phillipeans) less common in childhood, 30-50% adults immune (ultraviolet radiation inactivate virus in skin lesions

Question 3

If a woman believes she has had a significant exposure to chickenpox whilst pregnant what should you do?

Answer 3

Take a Hx, 1. is this a significant exposure/from tropical/subtropical country 2. Have they had previous infection.

If singificant exposure with 10 days and no previous infection

• take bloods for VZV-specififc IgG
• if negative give varicella zoster immune globulin (VZIG)

Question 4

How does gestation effect the transmission of VZV to the fetes?

Answer 4

High with later gestation, significant in last 4 weeks of gestation

Question 5

What are the effects of VZV on the developing fetes?

Answer 5

Skin scarring
Limb hypoplasia
Neurological features

Question 6

What complications of VZV can occur in the mother

Answer 6

pneumonia, hepatitis and encephalitis

Question 7

What are the features of CMV congenital infection?

Answer 7

Sensorineural Hearing Loss
Visual Impairment
Microcephaly
Low Birth weight
Seizures
Cerebral Palsy
Hepatosplenomagaly with jaundice
Thrombocytopenia with petechial rash

Question 8

What is the risk of congenital CMV if 1st infection in pregnancy versus re-infection?

Answer 8

Primary: 30-40%
Recurrent: 1-2%

risk higher in later gestation

Question 9

What % of fetus are symptomatic at birth?

Answer 9

10%, a further 10-15% will become symptomatic in later life

Question 10

How can you diagnose fetal CMV infection in utero? At what time should this be done?

Answer 10

Diagnosis of fetal CMV infection is via amniocentesis
Amniocentesis should not be performed for at least 6 weeks after maternal infection and not until the 21st week of gestation

Question 11

How can CMV be tranmitted?

Answer 11

Breast milk
urine - changing nappies + poor hand hygiene 
Saliva
Genital secretions 
Blood/organs

Question 12

How can mother be treated with active CMV?

Answer 12

No treatment

Question 13

What is the most commenest congenital infection?

Answer 13

CMV 0.5% all pregnancies It is the leading non-genetic cause of sensorineural hearing loss (SNHL) and a major cause of neurological disability.

Question 14

How do woman with CMV present?

Answer 14

Mostly asymptomatic, some present with infectious mononucleosis (glandular fever), including fever, malaise, myalgia, cervical lymphadenopathy and, less commonly, hepatitis and pneumonia

Question 15

fifth disease, slapped cheek syndrome and erythema infectiosum are all names for what infection?

Answer 15

Parovirus B19

Question 16

Parvovirus is what type of genetic material

Answer 16

single stranded DNA

Question 17

How does parvovirus B19 present?

Answer 17

Mild febrile fever, followed by rash which may appear as slapped cheeks, often itchy and worse in hot water
Arthraligia effecting the small joints

Question 18

Risk to fetus of parvovirus B19 in pregnancy?

Answer 18

Fetal loss
Hydrops (fetal oedema)
Anaemia
Heart failure

Most at risk < 20 weeks

Question 19

How do you test for previous parvovirus B19 infection?

Answer 19

IgG for parvovirus - detected (previous infection)

IgM positive for 3 months post infection

Question 20

How are babies with suspected Parvovirus B19 infection managed?

Answer 20

Specialist fetal monitoring may include:
Serial fetal ultrasound scans and Doppler assessment to detect fetal anaemia, heart failure, and hydrops. Ultrasound scanning may start around 4 weeks after the onset of symptoms or estimated time of seroconversion.
Hydrops fetalis may present on ultrasound with the development of ascites and thickening and enlargement of the fetal heart.
If there is suspected fetal hydrops, options include:
Parvovirus B19 viral DNA detection in amniotic fluid.
Fetal blood sampling and intrauterine red blood cell transfusion, which may reduce the fetal mortality rate.

Question 21

How can herpes infection of the newborn present

Answer 21

High morbidity/mortality
● disease localised to skin, eye and/or mouth
● local central nervous system (CNS) disease (encephalitis alone)
● disseminated infection with multiple organ involvement.

Question 22

How to manage first time infections of genital herpes
I) 1st/2nd trimester
II) 3rd trimester

Answer 22

I) Prophylacitc acyclovir from 36 weeks (and active mgmt of initial infection) and normal delivery
II) Tx with acyclovir, offer C/S

Question 23

How to manage recurrent herpes in pregnancy

Answer 23

Risk of tramission to baby very low 1-3%, consider acyclovir (400 TDS) from 36 week

Question 24

What type of genetic material is rubella virus

Answer 24

Single stranded RNA (like hepatitis and HIV)

Question 25

What type of vaccine is the rubella vaccine?

Answer 25

Live attenuated

Question 26

How does congenital rubella syndrome present?

Answer 26

Congenital rubella infection teratogenic with poor prognosis and significant complications (sensorineural deafness, cataracts and cardiac abnormalities most common)

Worst in earlier gestations. Little impact after 20th weeks.

Question 27

At the time mother presents with maculopapular rash, what will serological testing show?

Answer 27

IgG & IgM negative

→ will become positive after 5 das

Question 28

What is the TX of rubella

Answer 28

No treatment, prevent with infection