Congenital Infections of the Newborn
Fact Sheets for Health Professionals
Congenital infections in the newborn are either transmitted via the placenta during pregnancy or 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 for: (TO) Toxoplasmosis, (R) Rubella, (C) Cytomegalovirus, (H) Herpes simplex.
These infections were grouped together as a convenient reminder of their common features. The term TORCH is now outdated and best avoided, but some still find it a useful aid in remembering some causes of infection. It is now known that many other agents may cause congenital infections, such as:
· Varicella zoster (the chickenpox virus).
· Hepatitis B.
· HIV (human immune deficiency virus).
· Chlamydia trachomatis.
· 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 for the mother to catch these infections, because there is greater risk of the foetus 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. For 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 immunisation 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).
Throughout the world there are wide regional variations in the prevalence of toxoplasma infections. In Australia, between sixty and seventy per cent of women of child-bearing age are susceptible, but toxoplasma infection during pregnancy is uncommon, occurring in approximately two in every 1,000 pregnancies.
Toxoplasmosis is mainly acquired from cat faeces or eating undercooked meat. The infection may be asymptomatic or produce only mild symptoms in the mother. Infection early in the pregnancy may cause the death of the foetus and abortion; infection later can cause foetal damage, stillbirth or a liveborn 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 of transmission is about fifty per cent and is dependent upon the stage of the pregnancy during which the maternal infection developed. The risk of foetal infection is fifteen, forty-five and seventy per cent during the first, second and third trimesters respectively. In contrast the risk of foetal damage resulting in spontaneous abortion or symptomatic disease at birth is greatest if infection occurs early in pregnancy.
While severe disease is seen in eighty per cent of infants delivered to mothers who acquired the infection in the first trimester, only fifty per cent of infants are symptomatic at birth if the maternal infection was acquired in the second trimester. Although maternal infection in the third trimester rarely results in foetal 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 and must be guarded.
In general, the earlier in pregnancy the mother contracts rubella, the greater the risk of severe generalised involvement of the foetus (cataracts, deafness, congenital heart disease, microcephaly, hepatosplenomegaly and thrombocytopaenia). In the first trimester, the rate of foetal infection is nearly fifty per cent of which as many as eighty per cent develop the Congenital Rubella syndrome. Proven rubella infection with a blood test before 13 weeks gestation can be a reason for termination of the pregnancy. Between 13 and 16 weeks, the foetal infection rate is ten to thirty per cent resulting in one-third becoming deaf and demonstrating mild intellectual disability. After 16 weeks the risk is very low. Immunisation decreases the incidence of infection in the general population and therefore reduces the risk to pregnant mothers and their babies.
Rubella immunisation is offered to all children in Australia, resulting in a low rate of congenital rubella. However, the best method of personal prevention is for women to have their rubella immunity checked before trying to conceive and to be immunised if necessary.
Cytomegalovirus (CMV) is the most common cause of intra-uterine infection. About fifty per cent of women of child-bearing age remain susceptible to CMV infection and one per cent of women who are susceptible at the beginning of pregnancy will acquire a primary infection during pregnancy. Unlike rubella, foetal damage may follow primary infection, or rarely recurrent infection, at any stage of pregnancy. Risk of foetal infection is greatest (thirty to forty per cent) during primary maternal infection. Nevertheless, only ten of infants born with congenital CMV are symptomatic at birth. 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 (HSV) infection of the newborn is usually acquired from the mother at birth, through genital herpes of which the mother is frequently unaware. It occurs in approximately one in 10,000 births. As with CMV, the risk of perinatal herpes is greater with a primary (forty per cent) than recurrent (less than five per cent) infection. It can cause local infection of the skin, eyes and mucous membranes and may 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 foetal scalp electrode monitoring should be avoided. The baby may be delivered by elective caesarean section because of the risks of infection with a vaginal delivery. However, caesarean section does not always prevent perinatal infection.
Varicella Zoster (Chickenpox)
This is uncommon in women of child bearing age, and the risk to babies is usually low. The risk of a baby being affected by 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 after delivery is associated with sever disease and requires parenteral Acyclovir therapy.
Active maternal syphilis is uncommon in Australia and occurs in about one in every 2,000 pregnancies, but in untreated primary or secondary disease there is a high risk of stillbirth, premature delivery, neonatal death, or developing features of congenital syphilis. While foetal infection can be cured by treatment of the mother, preferably early in pregnancy, if foetal damage has occurred it may not be reversible. A major problem is that the clinical and laboratory signs of early infection in the neonate re not always present at birth, but may develop in the first few weeks or months of life in the untreated infant. By contrast, penicillin treatment of the affected infant in the neonatal periods prevents the complications of late congenital syphilis.
In Australia, up to two per cent of pregnant women are chronic hepatitis B surface antigen (HBsAg) carriers. Of these women, thirty per cent are hepatitis B envelope antigen (HBeAg) positive and these mothers can infect nearly ninety per cent of their offspring. Infection occurs predominantly during delivery from abrasions in the infant's skin or mucosa, or from small materno-foetal bleeds across the placenta during labour. Almost all infections in the neonate are asymptomatic, but more than ninety per cent become chronic carriers themselves and are at high risk of chronic livery disease, including cirrhosis and liver cancer, by middle age. Screening of all pregnancies for HBsAg and in the future, universal immunisation against hepatitis B will eventually reduce the burden of the disease to the affected individuals and the community.
This virus quite commonly causes a mild febrile illness with rash in older children and adolescents (for example, slapped cheek and fifth disease). It is easily mistaken for rubella and like this illness can also cause joint symptoms in adults. Approximately fifty per cent of adults are susceptible and transmission rates in households reach fifty per cent, while within schools or day care centres rates of twenty to thirty per cent are observed. Foetal infection occurs in thirty per cent of maternal infections with ten per cent foetal death occurring predominantly in the second trimester from severe anaemia and hydrops foetalis.
HIV (Human Immune Deficiency Virus)
Infection is transmitted transplacentally, during delivery or from breast milk. The transmission rate is between ten an thirty per cent. It is believed that the virus is transmitted predominantly at delivery. However, in nearly fifteen per cent 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.
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. Estimates of Chlamydia prevalence in pregnant Australian women are one to two per cent 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, which may develop in as many as thirty per cent of exposed infants and can result in a prolonged respiratory illness with cough and tachypnoea. For both infections oral erythromycin is the treatment of choice.
Genital mycoplasmas have been suggested as cause for 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 time up to eight to ten weeks. Approximately fifteen per cent of pregnant women carry GBS in their vagina and the principal risk factor for disease (two in every 1000 live births) is absence of type-specific maternal IgG antibody. 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 intra-partum antibiotics for pregnancies at high risk for GBS infections.
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. Since rubella is the only TORCH infection screened for at booking, the other infections are usually only suspected during pregnancy if abnormalities in the foetus are detected on ultrasound scan or if a pregnant woman has contracted a flu-like illness (unexplained fever, rash, joint pain, and so on). 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 recognisable 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). With most modern laboratories the waiting time for results should not exceed more than a few days.
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. Close co-operation with the microbiology laboratory and experts in congenital infections is important when congenital infection is suspected.
Toxoplasma: Specific IgM antibody in blood (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 rival culture.
CMV: Isolation of the virus in the throat washings or urine in the first two to three weeks of life. Absence of IgG 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 virus should be cultured if perinatal infection is suspected.
Direct communication between the clinician and the microbiologist allows optimal use of laboratory resources and the most logical sequence of testing.
Advice for Women Contemplating Pregnancy
Women can reduce the risk of these infections during pregnancy by following these recommendations:
· Young children should be fully immunised (including MMR).
· Mothers should know their rubella immune status, preferably before trying to conceive but certainly during pregnancy by presenting for 'booking' investigations.
· 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.
Garland S, Gilbert GL. Investigation of congenital infection - the TORCH screen is not a legitimate test. Medical Journal of Australia, 1933; 159: 346-48.
Editorial. TORCH syndrome and TORCH screening. Lancet, 1990; 335: 1559-61.
Gilbert GL. Antenatal screening & prenatal diagnosis of intrauterine infection. Centre for Infectious Diseases and Microbiology, Westmead Hospital, University of Sydney. Wild and Woolley, Glebe NSW. Monograph series, No. 1, 1994.
Written expert opinion from Dr. Keith Grimwood, Paediatrician, Royal Children's Hospital, Melbourne.
For Further Information
General practitioner and paediatrician.
Developed by the Centre for Community Child Health & Ambulatory Paediatrics Royal Children's Hospital, Melbourne for the Victorian Government Department of Human Services.
Produced by the Office of the Family, Youth and Family Services Division, Victorian Government Department of Human Services.