TORCH

TORCH refers to the congenital infections toxoplasmosis, others (syphilis, hepatitis B), rubella, cytomegalovirus and herpes simplex. Other pathogens causing congenital infection include HIV, parvovirus B19, varicella and Zika.

Maternal risk factors include lapsed immunisations, sexually transmitted infections, and animal exposures during pregnancy. Timing matters: with the exception of HSV, infection in the first trimester has the worst outcome. Approximately 2% to 3% of all congenital anomalies are attributed to perinatal infections.

The shared neonatal picture

Many of these infections look alike in the newborn — rash (maculopapular, petechial “blueberry muffin”, or purpuric), microcephaly, sensorineural hearing loss, chorioretinitis, hepatosplenomegaly and cardiac anomalies.

So think TORCH in any small-for-gestational-age baby with a rash, murmur or ocular finding, and work each pathogen up individually rather than relying on a panel. A “TORCH titre” is a panel of IgG tests: it may show whether the mother has been infected, but it is not useful for making a definitive diagnosis.

Differentials that mimic it include Zika (intracranial calcification), parvovirus B19 (hydrops, marrow suppression), pre-eclampsia and other maternal causes of growth restriction, and metabolic or genetic syndromes.

Toxoplasmosis

Acquired from undercooked or cured meat, unpasteurised dairy, soil- or water-contaminated produce, and cat faeces. Usually asymptomatic in the mother.

Transplacental transmission is most common in the third trimester, but the earlier the infection, the more severe the congenital malformations.

Test serology if acute toxoplasmosis is clinically suspected in pregnancy; amniotic fluid PCR from ≥18 weeks. Fetal ultrasound findings of intracranial hyperechogenic foci or calcification and cerebral ventricular dilatation are poor prognostic signs.

Congenital disease presents with growth restriction and low birth weight, hepatosplenomegaly, jaundice, chorioretinitis, intraparenchymal calcification and anaemia. Antenatal treatment is specialist-directed — spiramycin for fetal prophylaxis, and pyrimethamine/sulfadiazine/folinic acid where fetal infection is established.

Prevention advice:

• Cook meat thoroughly, or freeze it for several days before cooking.
• Wash or peel all fruit and vegetables, and wash surfaces that contacted raw meat, poultry or seafood.
• Avoid unpasteurised milk and raw shellfish.
• Wear gloves and wash hands after handling cat litter, sand or soil.
• Have someone else change the cat litter daily — fresh cat faeces are not yet infectious.

Rubella

Transmitted to the mother by aerosol and to the fetus through the placenta. Can cause miscarriage, fetal infection, stillbirth or growth restriction.

Congenital rubella syndrome includes low birth weight, hepatosplenomegaly, cataracts, congenital heart disease (patent ductus arteriosus, ventricular septal defect) and a petechial rash. Congenital sensorineural hearing loss is very common.

Fetal infection is confirmed by rubella-specific PCR on chorionic villus or amniotic fluid samples. Once established, congenital rubella cannot be treated — but it is the most common vaccine-preventable neonatal disease, and immunity should be checked at the start of every pregnancy.

Cytomegalovirus (CMV)

The most common congenital infection worldwide and the leading non-hereditary cause of sensorineural hearing loss in children, affecting over 1 in 200 live births in developed countries.

Around 85% to 90% of affected newborns are asymptomatic at birth, and 10% to 15% of those still develop long-term morbidity. Symptomatic disease carries a mortality risk of up to 7% to 12% in the early neonatal period.

The main risk factor for maternal primary infection is close contact with young children — infected children under 2 shed virus in urine and saliva for around 24 months. Transplacental transmission risk is 30% to 35% after primary maternal infection versus 1.4% for non-primary infection, but severity is worst with first-trimester infection.

Diagnosis: primary maternal infection requires documented seroconversion; IgM alone is non-specific, and IgG avidity helps date the infection. Fetal diagnosis is by amniotic fluid PCR, best performed after 21 weeks and at least 7 weeks after maternal infection — sensitivity is about 71% after 21 weeks versus 30% before.

Treatment is limited but no longer absent. CMV hyperimmune globulin does not reduce maternal-fetal transmission and is not recommended routinely. European expert guidance recommends oral valaciclovir started as early as possible in primary periconceptional or first-trimester infection. Symptomatic neonates treated with oral valganciclovir for six months show better outcomes at two years; valganciclovir is not used prenatally.

Prevention rests on hygiene advice. The Australian Government’s Living Evidence for Australian Pregnancy and Postnatal Care guideline recommends advising all pregnant women about hygiene measures to help reduce the risk of cytomegalovirus infection. Hygiene precautions, including avoiding contact with a child’s saliva or urine and handwashing after such exposure, reduce the risk of CMV in pregnancy and are acceptable to women. Around one in 200 infants in comparable high-income countries are born with congenital CMV, making it the most common congenital infection. In practice that means avoiding contact with a young child’s saliva or urine, not sharing food, cups or utensils, and washing hands after nappy changes and feeds.

Herpes simplex virus (HSV)

The mother acquires HSV sexually; the fetus is infected by ascending infection or, far more often, exposure during delivery to virus shed from the vulva, vagina, cervix or perianal skin.

Maternal primary infection in the third trimester carries the highest risk of neonatal infection. Reactivation is 10 to 30 times less likely to transmit than primary infection. Caesarean delivery reduces but does not eliminate the risk.

Neonatal disease usually appears 10 to 21 days after exposure in one of three forms — skin-eye-mouth, CNS, or disseminated. Any of them can present simply as fever. Treat maternal infection with aciclovir or valaciclovir; the neonate needs a full sepsis workup including lumbar puncture, and high-dose intravenous aciclovir.

Syphilis and the “others”

Congenital syphilis matters because it is preventable and treatable. Transmission is transplacental or in the birth canal, and exceeds 80% in recently infected mothers. Test in pregnancy and treat any positive result.

The neonate may show cutaneous lesions on palms and soles, hepatosplenomegaly, jaundice, funisitis and nasal discharge (“snuffles”), with periostitis on bone x-ray. All babies at risk need an RPR compared with the mother’s titre.

Hepatitis B and HIV are also transmitted vertically and are covered by routine antenatal screening; children born to mothers with HIV need PCR testing from birth and should not breastfeed.