2 Fetal and Neonatal Infection Will cover infections that occur in the pre, peri and post natal periods.Baby tends to be susceptible because ofImmature 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.ascendingin utero (congenital)transplacentalintra partumgenitalmotherpost partumothers
4 Infections transmitted vertically In uteroRubella, hepatitis B and C, HIV, CMV, toxoplasmosis, listeriosis, syphilis, herpes.Group B Strep, herpes (ascending)Intra partumHepatitis B and C, HIV, Group B Strep, gonorrhoea, chlamydia, HERPES.Post partumHIV, Group B Strep, herpes
5 Antenatal screeningJuly 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 infectionsWhy?Not clinically obvious in motherPresence 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 activeIncidence in community is about 1% (Aus).Higher in some risk groups.Risk of transmission to baby is predictable90% 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 MIs $15 million to prevent 3 cases worth it? Could more cases be prevented by spending the $15 million elsewhere?
10 A case for “no”: CMVCytomegalovirus 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 birthsDoes 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 babyColonized 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, RANZCOGVaginal 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 diseaseMay be asymptomatic or flu like illness with rash.Long term immunity follows infection.Immunity from vaccine can wane.TransmissionTransplacental during viraemic phase.Neonatal infectionMost 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 ScreeningScreens 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. ToxoplasmosisA 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 neonateRisk 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 ListeriosisAn organism commonly encountered in food – especially soft cheeses. Can grow in the cold, so refrigeration not a total solution.Adult infectionMild flu like illness – unless immunocompromised.Organism gets into bloodstream (Trojan Horse)Neonatal infectionTransplacental transmissionSpontaneous abortion, stillbirth, septicaemia, abscessesPrevention consists of modifying eating habits. At a public health level, screen foods, use pasteurized milk for cheeses.
18 Neonatal herpesMaternal 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.