Congenital Infections of the Newborn
Congenital infections in the newborn are either transmitted via :
1. the placenta during pregnancy or
2. acquired from the birth canal at the time of labour.
TORCH is an acronym based on the first letters of some of the more important infections affecting
babies and children. The letters stand tor: (TO) Toxoplasmosis, (R) Rubella, (C) Cytomegalovirus,
(H) Herpes simplex.
It is now known that many other agents may cause congenital infections, such as:
Varicella zoster (the chickenpox virus).
Syphilis.
Hepatitis B.
Parvovirus.
HIV (human immune deficiency virus).
Chlamydia trachomatis.
Mycoplasma.
Group B streptococcus.
It is therefore more useful to consider these infections separately and look at the unique features of
each infection.
Important Points for Primary Care Health Professionals
The time to provide information to mothers about these infections is before pregnancy
begins, because this is the best time for preventive measures.
The first trimester is usually the most dangerous time tor the mother to catch these
infections, because there is greater risk of the fetus being affected.
Infection in the mother can often be accompanied by very trivial symptoms , or even none
at all. so the condition is not usually diagnosed.
Infection in the mother does not always mean the baby will be affected. I or many infections,
the baby is more at risk at particular stages of pregnancy (for example, first trimester for
rubella, at delivery for herpes simplex). For some the infection risk at any stage is low.
Some infections can be avoided by the mother through simple measures, such as
immunization for rubella during childhood and before pregnancy. Some Infections are
treatable for example; syphilis is treated effectively with penicillin.
The effects of congenitally acquired infection may be quite different from and more
severe than, the effects of the same infection acquired in the usual way ( for example,
rubella in children usually results in a mild fever and itchy rash while congenital rubella
can result in a baby being born with deafness, cataracts, heart defects or other
problems).
Toxoplasmosis
Toxoplasmosis is mainly acquired from cat feces or eating undercooked meat. The infection
may be asymptomatic or produce only mild symptoms in the mother.
Infection early in the pregnancy nun cause the death of the fetus and abortion; infection later
can cause fetal damage, stillbirth or a live born infant with damage to the brain and body
organs.
Infection in the mother does not always cause congenital disease in the baby.
Overall, the rate o f transmission is about fifty per cent and is dependent upon the static of the
pregnancy during which the maternal infection developed.
In contrast the risk of fetal damage resulting in spontaneous abortion or symptomatic disease
at birth is greatest if infection occurs early in pregnancy.
Although maternal infection in the third trimester rarely results in fetal damage, neurological
injury and chorioretinitis may appear months or years later.
Symptomatic babies are born with hydrocephalus, chorioretinitis and cerebral calcification.
There is treatment available for infected babies, but in contrast to those with subclinical
infection the outlook for babies with neurological involvement is uncertain .
Rubella
In general, the earlier in pregnancy the mother contracts rubella, the greater the risk of severe
generalized involvement of the fetus (cataracts, deafness, congenital heart disease,
microcephaly, hepatosplenomegaly and thrombocytopenia).
Proven rubella infection with a blood test before 13 weeks gestation can be a reason for
termination of the pregnancy .
Immunization decreases the incidence of infection ,in the general population and therefore
reduces the risk to pregnant mothers and then babies.
Rubella immunization is offered to all children in Australia, resulting in a low rate of congenital
rubella.
Rubella immunization is offered to all children in Australia, resulting in low rate of congenital
rubella. However, the best method of personal prevention is for women to have their rubella
immunity cheeked before trying to conceive and to be immunized if necessary.
Cytomegalovirus
Cytomegalovirus (CMV) is die most common cause of intra-uterine infection.
unlike rubella, fetal damage may follow primary infection, or rarely recurrent infection, at any
stage of pregnancy.
These more severely affected infants are more likely to have been exposed to a primary
maternal infection during the first trimester. Most (eighty to ninety per cent) infants who are
symptomatic at birth (hepatosplenomegaly, jaundice, petechiae and microcephaly) and another
ten per cent of infants with asymptomatic infection at birth develop late complications such as
sensori-neural deafness, intellectual disability or seizures.
Herpes Simplex
Herpes simplex (MSV) infection of the newborn is usually acquired from the mother al birth,
through genital herpes of which the mother is frequently unaware.
It can cause local infection of the skin, eyes and mucous membranes and max disseminate to
involve multiple organs including the lungs, liver, adrenals and brain.
Even with the availability of anti-viral agents such as Acyclovir, mortality and morbidity within
survivors remains high in neonates with meningoencephalitis or disseminated forms of the
disease.
If it is known that the mother has active herpes during labour, prolonged rupture of membranes
and fetal scalp electrode monitoring should be avoided.
Others
Varicella Zoster (Chickenpox)
the risk of baby being affected In congenital infection and abnormalities is one to two per cent if
the mother is infected during second trimester, sometimes resulting in severe damage with skin
scarring, ocular lesions, seizures and limb abnormalities.
Transmission later in pregnancy can result in the baby being affected by zoster (shingles-like
rash) or chickenpox (the usual infection).
If the mother develops chickenpox between five days before delivery to two days after, the
baby is given zoster immune globulin because protective maternal antibodies will not be
present by the time of delivery. The development of varicella lesions in the infant five to ten
days atter delivery is associated with sever disease and requires parenteral Acyclovir therapy.
Syphilis
Untreated primary or secondary disease there is a high risk of stillbirth, premature delivery.
neonatal death, or developing features of congenital syphilis.
While fetal infection can be cured by treatment of the mother, preferably early in pregnancy, if
fetal damage has occurred it may not be reversible.
By contrast, penicillin treatment of the affected infant in the neonatal periods prevents the
complications of late congenital syphilis.
Parvovirus
This virus quite commonly causes a mild febrile illness with rash in older children and
adolescents (for example, slapped cheek and fifth disease).
fetal infection occurs in thirty per cent of maternal infections with ten per cent fetal death
occurring predominantly in the second trimester from severe anemia and hydrops fetalis.
HIV (Human Immune Deficiency Virus)
Infection is transmitted trans-placentally, during delivery or from breast milk.
The transmission rate is between ten and thirty per cent. It is believed that
the virus is transmitted predominantly at delivery.
However, in nearly fifteen percent of perinatal HIV infections, breast feeding has been
implicated.
Infected neonates can be asymptomatic for several years but up to thirty per cent will develop
symptoms and become very ill within the first few months of life.
Chlamydia Trachomatis
This sexually transmitted infection is often asymptomatic in the mother, although infected
women may have inflammation of the cervix, fallopian tubes or urethra.
The infection is transmitted during delivery.
Conjunctivitis will develop in fifty to sixty per cent of infants born to infected mothers, but is
rarely severe.
A more serious complication is Chlamydia pneumonia.
For both infections oral erythromycin is the treatment of choice.
Mycoplasmas
Genital mycoplasmas have been suggested as cause tor recurrent miscarriage,
chorioamnionitis. preterm birth, low birth weight stillbirth and post-partum fever. It is uncertain
whether there is any value in screening for these organisms, as other factors may have caused
these adverse outcomes.
Group B Streptococcus
Group B streptococcus (GBS) is the commonest cause of overwhelming sepsis (respiratory
distress, shock and/or meningitis) in neonates during the first week of life and may occur at any
lime up to eight to ten weeks. Preterm labour, prolonged rupture of the membranes and
maternal fever are associated with a higher risk of infection.
Infected neonates are treated with antibiotics.
Until an effective vaccine is developed, some experts recommend intrapartum antibiotics for
pregnancies at high risk for GBS infections.
Clinical Presentation
In general, intra-uterine infections are suspected in two clinical situations:
During pregnancy
mother-to-be who is non-rubella immune (or does not know her status) is tested
(perhaps because of a flu-like illness or contact with a suspected case of rubella) and is
found to have been infected.
Sera and suitable specimens are collected as soon as possible and in all cases,
discussion of testing and counselling on various aspects of management must be
undertaken. Treating the mother during pregnancy (for example, if a recognizable
illness is found and diagnosed) and then the baby during the first 12 months of life may
prevent or reverse damage for many of these children. The option of termination of
pregnancy, if indicated, should be discussed with the mother by expert medical staff
able to present a balanced overview of likely procedures and outcomes.
After pregnancy
the baby may have signs which lead parents and clinicians to suspect an abnormality
and clinicians may test for one or more congenital infections.
These signs may include combinations of an abnormal appearance, eye abnormalities,
seizures, small size, big or small head cardiac murmur, enlarged abdominal organs,
jaundice, skin rashes petechiae and others.
Testing is likely to be more effective if aimed at identifying the type of infection most
likely to be present (based on clinical findings).
Investigations
The collection of appropriate specimens as soon as possible and testing maternal/infant
serum in parallel is of utmost importance. Maternal sera collected early in pregnancy
should be stored for at least 12 months.
Toxoplasma: Specific IgM antibody in blood I (if IgG positive), tissue culture, PCR
(polymerase chain reaction testing) and follow-up serology may be required.
Rubella: Specific IgM antibody in blood (if IgG positive) and tissue culture.
CMV: Isolation of the virus in the throat washings or urine in the first two to three
weeks of life. Absence of lgG in blood is a quick method of excluding the
diagnosis.
HSV: HSV can be difficult to diagnose but the virus can be identified by PCR,
direct antigen testing by immunofluorescence or by electron microscopy The vims
should he cultured if perinatal infection is suspected
Prevention
Women can reduce the risk of these infections during pregnancy by following these
recommendations:
Young children should he fully immunized (including MMR).
Mothers should know their rubella immune status, preferably before trying to
conceive but certainly during pregnancy by presenting for booking
investigations.
While pregnant:
Wash hands after changing nappies or handling any body secretions.
Wash hands before and after food preparation.
Avoid undercooked meats.
Do not handle cat faeces while pregnant.
Try not to kiss children full on the mouth.
Do not garden without gloves.
Do not share cutlery or toothbrushes with children.