1. Fetal and Neonatal Infection

2. Fetal and Neonatal Infection
Will cover infections that occur in the pre, peri and post natal periods.
Baby tends to be susceptible because of
Immature host defences.
Primary encounter with the organism.
Some protection from maternal antibodies (passive)

3. Modes of transmission ascending in utero (congenital) transplacental
The term “VERTICAL TRANSMISSION” refers to transmission that is unique to a mother/baby relationship. Not all neonatal infections where the mother is the source are transmitted vertically.
ascending
in utero (congenital)
transplacental
intra partum
genital
mother
post partum
others

4. Infections transmitted vertically
In utero
Rubella, hepatitis B and C, HIV, CMV, toxoplasmosis, listeriosis, syphilis, herpes.
Group B Strep, herpes (ascending)
Intra partum
Hepatitis B and C, HIV, Group B Strep, gonorrhoea, chlamydia, HERPES.
Post partum
HIV, Group B Strep, herpes

5. Antenatal screening
July 2003, Royal Australian and New Zealand College of Obstetricians and Gynaecologists recommends:
Rubella, syphilis, mid stream urine, HepB
(first visit)
Vaginal swab for Group B Streptococcus.
( weeks)
Variable – HIV, toxoplasmosis, CMV, HepC

6. Antenatal Screening Why? Not clinically obvious in mother
A number of maternal infections affect the outcome of the pregnancy, yet we only screen the mother for some infections
Why?
Not clinically obvious in mother
Presence of a reliable test.
Likelihood / outcome of transmission.
Prevalence of maternal infection.
Possibility of intervention.

7. A case for “yes”: Hepatitis B
Hep B infection: recovery or carrier or chronic active
Incidence in community is about 1% (Aus).
Higher in some risk groups.
Risk of transmission to baby is predictable
90% if chronic active, 10% if carrier.
Infection with Hep B is always bad, but when infected as a neonate it is worse.
Greater chance of becoming chronic active AND increased risk of liver cancer AND “spreader”.
Good intervention with passive and active immunization.
Risk to HCW in obstetric setting !

8. A case for “maybe”: HIV HIV+ mum = 30% HIV+ babies.
Intervention is possible: reduce to 2%
Antiviral therapy, caesarian birth, bottle feeding.
Up to 1998 (Aus) 176+ mums and 60+ babies. Estimated 100 new HIV cases in women per year. How many have babies? (assume 10, and 3 babies ? Get HIV)
Cost of screening per year = 15 M
Is $15 million to prevent 3 cases worth it? Could more cases be prevented by spending the $15 million elsewhere?

10. A case for “no”: CMV
Cytomegalovirus infection is common and mild in adults BUT can be devastating to the fetus.
Once infected, we are infected for life, but only a “primary” first time infection while pregnant puts the fetus at risk. (? 1 in 200 pregnancies).
Risk of transmission is 40%, but outcome is unpredictable (serious to asymptomatic).
Only intervention is termination.
CMV fails (as a candidate for screening) because the outcome of transmission is so unpredictable and intervention so drastic.

11. Group B Streptococcus (GBS)
The most common cause of serious neonatal infection?
1 – 5 per 1000 births
Does NOT cause maternal disease, but simply colonizes the vagina.
Transmitted to neonate by the prenatal ascending route, intrapartum or after birth (horizontally NOT vertically).
Result of transmission to baby
Colonized only (most common)
Early onset disease (septicaemia or pneumonia)
Late onset disease (meningitis)

12. Group B Streptococcus Risk factors for transmission AND disease.
Colonized mother.
Premature birth (less than 37 weeks).
Prolonged rupture of membranes (greater than 18 hrs)
Prevention of DISEASE (early onset).
Give intrapartum penicillin (greater than 4hrs pre ‘del)
Does NOT prevent transmission, but modifies outcome.
Small risk of penicillin allergy anaphylaxis.

13. GBS: prevention strategies
Possible areas for intervention.
Eradicate carrier state in mother – NO.
Stop transmission – NO.
Stop colonization becoming disease – YES.
July 2003, RANZCOG
Vaginal swab culture for GBS at wks.
If positive, give penicillin prophylaxis.
If culture impractical - obstetric risk factors.
Previous GBS infected baby, pre-term labour, prolonged rupture of membranes.
Future potential of vaccination.

14. Rubella (German measles)
Adult disease
May be asymptomatic or flu like illness with rash.
Long term immunity follows infection.
Immunity from vaccine can wane.
Transmission
Transplacental during viraemic phase.
Neonatal infection
Most risk during first trimester (90% risk of severe)
Spontaneous abortion, still birth, deafness, blindness

15. Rubella prevention and screening
Routine vaccination of all infants, NOT just adolescent girls.
Less than 5% of “potential mums” are not immune, and risk of exposure is LOW.
Antenatal Screening
Screens for maternal immunity NOT disease.
If NOT immune, cannot vaccinate.
If NOT immune, can easily prove disease if suspected.
Termination is only intervention.

16. Some notable Australian cases linked to kangaroo meat.
Toxoplasmosis
A parasite of cats and herbivores.
Transmission to humans (common – 45%)
Old cat faeces or ingestion of poorly cooked meats.
Mild disease, but infection is lifelong.
Transmission to neonate
Risk only if mother has first infection while infected.
50% of the 0.5% that seroconvert will transmit.
Transplacental – more severe early in gestation.
Stillbirth, acute or latent blindness (20 yrs)
Some notable Australian cases linked to kangaroo meat.

17. Listeriosis
An organism commonly encountered in food – especially soft cheeses. Can grow in the cold, so refrigeration not a total solution.
Adult infection
Mild flu like illness – unless immunocompromised.
Organism gets into bloodstream (Trojan Horse)
Neonatal infection
Transplacental transmission
Spontaneous abortion, stillbirth, septicaemia, abscesses
Prevention consists of modifying eating habits. At a public health level, screen foods, use pasteurized milk for cheeses.

18. Neonatal herpes
Maternal infection can be primary, re-activated or latent. (10 – 20% of Aus women at antenatal clinics are HSV2+)
Transmission to baby.
Transplacental (rare).
Intra partum (accounts for most cases)
Post partum.
Risk to baby depends on maternal infection.
Highest if primary maternal infection late in pregnancy (50%)
Less if recurrent (less virus – risk is less than 10%).
Less if latent and shedding.

19. Neonatal herpes Disease manifestations in baby.
Localized, encephalitis, disseminated.
Very high mortality, even with therapy high morbidity.
Prevention (very complicated and non standardized)
Blood tests poor at distinguishing HSV-1/2 and primary or recurrent or latent in the mother.
Caesarian section in primary maternal, less convincing for recurrent or latent.
Antiviral drugs for mother and newborn.
Counseling for HSV- mothers with HSV+ partners.

20. Others
STD’s
Gonorrhoea, syphilis, chlamydia.
Tetanus