Residency · Residency · Pediatrics

Congenital Infections (TORCH)

Overview

TORCH is an acronym for infections acquired in utero or perinatally that cause significant neonatal morbidity: Toxoplasmosis, Other (syphilis, varicella, parvovirus B19, Zika), Rubella, Cytomegalovirus, and Herpes simplex virus. The timing of maternal infection during gestation profoundly influences the severity of fetal effects, with the general principle that earlier infection causes more severe structural anomalies while later infection carries a higher transmission rate but often milder disease. Congenital CMV is the most common congenital infection worldwide, affecting 0.5-1% of all live births. Because many congenital infections share overlapping clinical features, a systematic diagnostic workup is essential.

Shared Clinical Features

Several clinical findings are common across TORCH infections and should raise suspicion for congenital infection in any newborn: intrauterine growth restriction, hepatosplenomegaly, conjugated hyperbilirubinemia, thrombocytopenia with petechiae or purpura (the "blueberry muffin" rash representing dermal erythropoiesis), microcephaly, intracranial calcifications, chorioretinitis, sensorineural hearing loss, and hydrops fetalis.

<image>Clinical comparison table showing overlapping and distinguishing features of TORCH infections in neonates including characteristic intracranial calcification patterns (diffuse in CMV, periventricular vs. scattered/diffuse in toxoplasmosis, basal ganglia), eye findings, and skin manifestations</image>

Toxoplasmosis

Epidemiology and Transmission

Congenital toxoplasmosis is caused by Toxoplasma gondii, an intracellular protozoan parasite. Maternal acquisition occurs through consumption of undercooked meat, exposure to cat feces, or contact with contaminated soil or water. Congenital infection occurs only when the mother acquires a primary infection during pregnancy. The transmission rate increases with gestational age (10-15% in the first trimester, 60-80% in the third trimester), while severity is inversely related to gestational age at infection.

Clinical Presentation

The majority (70-90%) of infected neonates are asymptomatic at birth. When symptomatic, the classic triad consists of chorioretinitis, hydrocephalus, and intracranial calcifications with a characteristically diffuse or scattered pattern. Additional findings include hepatosplenomegaly, jaundice, anemia, thrombocytopenia, seizures, microcephaly or macrocephaly, and maculopapular rash. Without treatment, progressive chorioretinitis and intellectual disability develop over time.

Diagnosis

Maternal diagnosis relies on Toxoplasma IgG and IgM serologies with IgG avidity testing (low avidity indicates recent infection). Neonatal diagnosis uses Toxoplasma IgM and IgA, which are produced by the infant rather than passively transferred, along with PCR of CSF or blood. Head imaging reveals diffuse intracranial calcifications, and ophthalmologic examination demonstrates chorioretinitis that is often bilateral.

Treatment

Treatment consists of pyrimethamine combined with sulfadiazine and leucovorin (folinic acid) for 12 months. Pyrimethamine is given at 1 mg/kg/day for the first 6 months, then every other day for the remaining 6 months. Leucovorin prevents bone marrow suppression from pyrimethamine. CBC monitoring is performed weekly initially and then monthly. Treatment substantially reduces the risk of new chorioretinal lesions and neurodevelopmental sequelae.

Congenital Cytomegalovirus (CMV)

Epidemiology

CMV is the most common congenital infection, affecting 0.5-1% of all newborns, and represents the leading infectious cause of sensorineural hearing loss and intellectual disability. Maternal primary infection carries a higher transmission rate (30-40%) compared to reactivation or reinfection (1-2%), though non-primary maternal CMV can still cause symptomatic congenital disease.

Clinical Presentation

An important feature of congenital CMV is that 85-90% of infected infants are asymptomatic at birth. Among the 10-15% with symptomatic disease, findings include petechiae, purpura, and "blueberry muffin" spots; hepatosplenomegaly with conjugated jaundice; microcephaly; periventricular calcifications (a characteristic pattern distinguishing CMV from other TORCH infections); chorioretinitis; sensorineural hearing loss (which may be present at birth or develop progressively); intrauterine growth restriction; thrombocytopenia; and elevated transaminases. Critically, 10-15% of initially asymptomatic infants will develop sensorineural hearing loss or developmental delay by age 5.

Diagnosis

The gold standard is CMV PCR from urine or saliva collected within the first 21 days of life. This timing is essential because a positive CMV test after 21 days may represent postnatal acquisition and cannot confirm congenital infection. Saliva PCR has high sensitivity but should be confirmed with urine if positive due to potential breast milk contamination. Dried blood spot CMV PCR can retrospectively diagnose congenital CMV but has lower sensitivity.

The complete workup for confirmed congenital CMV includes head ultrasound or MRI (looking for periventricular calcifications, ventriculomegaly, and lenticulostriate vasculopathy), ophthalmologic examination, auditory brainstem response testing, CBC, hepatic function panel, and CSF CMV PCR if CNS disease is suspected.

Treatment

Valganciclovir at 16 mg/kg/dose given orally twice daily for 6 months is the standard treatment for symptomatic congenital CMV with CNS involvement, including isolated sensorineural hearing loss. The Kimberlin 2015 trial demonstrated that 6 months of treatment was superior to 6 weeks for hearing and neurodevelopmental outcomes. Treatment is not currently recommended for asymptomatic congenital CMV, though trials are ongoing. Monitoring during treatment must include CBC (neutropenia occurs in 20-30% of treated infants) along with hepatic and renal function. Neutropenia is managed by holding or reducing the dose if ANC falls below 500.

Congenital Rubella Syndrome

Epidemiology

Congenital rubella has been nearly eliminated in countries with high MMR vaccination rates but remains a concern in unvaccinated populations and endemic regions. Congenital infection occurs with maternal primary infection, with the highest risk during the first trimester (approximately 80% transmission in the first 12 weeks, decreasing to 25% by the end of the second trimester).

Clinical Presentation

The classic triad consists of sensorineural hearing loss (the most common manifestation), congenital heart disease, and cataracts. Cardiac lesions most commonly include patent ductus arteriosus and pulmonary artery stenosis. Eye findings include unilateral or bilateral cataracts, microphthalmos, glaucoma, and salt-and-pepper retinopathy. The "blueberry muffin" rash of dermal erythropoiesis, hepatosplenomegaly, jaundice, microcephaly, intellectual disability, and bone radiolucencies ("celery stalking" of long bones) complete the clinical picture. Expanded rubella syndrome may manifest years later with progressive panencephalitis, diabetes mellitus, and thyroid disease.

Diagnosis

Diagnosis relies on rubella IgM in infant serum (positive at birth or in the first months of life), viral culture or PCR from nasopharyngeal secretions or urine, and persistent rubella IgG beyond 6-12 months (beyond the expected decline of passively transferred maternal antibody).

Treatment

No specific antiviral therapy exists. Management is supportive, including cardiac surgery when needed, hearing aids or cochlear implants, and developmental support. Infected infants shed virus for months, making isolation precautions important. Prevention through maternal rubella vaccination prior to pregnancy is the primary strategy, noting that the live vaccine is contraindicated during pregnancy.

Congenital Herpes Simplex Virus (HSV)

Epidemiology

Neonatal HSV occurs in approximately 1 in 3,000-20,000 live births. While HSV-2 has been more common historically, the proportion of HSV-1 is increasing. The highest transmission risk (30-50%) occurs with maternal primary genital infection near delivery, while recurrent maternal infection carries less than 2% transmission risk due to the protective effect of transplacental antibodies. The route of acquisition is intrapartum in 85% of cases, postnatal in 10%, and in utero in only 5%.

Clinical Presentations (Three Categories)

Neonatal HSV is classified into three distinct categories. Skin, eye, and mouth (SEM) disease accounts for approximately 45% of cases and presents with vesicular skin lesions, keratoconjunctivitis, or oral ulcers, usually appearing at days 10-12 of life. It carries the best prognosis when treated promptly.

CNS disease accounts for approximately 30% of cases and presents with seizures, lethargy, poor feeding, and bulging fontanelle. CSF shows pleocytosis with elevated protein, and HSV PCR is positive. Critically, skin lesions may be absent in 30-40% of CNS disease cases.

Disseminated disease accounts for approximately 25% and presents with a sepsis-like picture including disseminated intravascular coagulation, hepatitis, pneumonitis, and shock. It carries the highest mortality at 30% even with treatment. It typically presents earlier, at days 5-9 of life, and liver involvement with markedly elevated transaminases is the hallmark.

Diagnosis

Diagnosis relies on HSV PCR of vesicle fluid, blood (plasma), and CSF. Surface cultures from the mouth, nasopharynx, conjunctivae, and rectum at 24 hours of life are used for exposed infants. HSV serology is not useful in neonates. Liver function tests and DIC panels should be obtained when disseminated disease is suspected.

Treatment

Intravenous acyclovir at 60 mg/kg/day divided every 8 hours is the standard treatment: 14 days for SEM disease and 21 days for CNS or disseminated disease. Following the IV course, oral acyclovir suppressive therapy at 300 mg/m2/dose three times daily for 6 months is given. The Kimberlin 2011 study demonstrated that suppressive therapy improves neurodevelopmental outcomes in CNS disease and reduces skin recurrences in SEM disease. Renal function and neutrophil count should be monitored during IV therapy.

<image>Algorithm for the evaluation and management of neonatal herpes simplex virus showing the three clinical categories (SEM, CNS, disseminated), diagnostic workup including HSV PCR from blood, CSF, and surface cultures, and treatment durations for each category</image>

Congenital Syphilis

Epidemiology

Congenital syphilis is caused by the spirochete Treponema pallidum and is experiencing a dramatic resurgence, with the CDC reporting 3,761 US cases in 2022 representing a 10-fold increase since 2012. Transmission occurs transplacentally at any stage of pregnancy, with the highest rates (60-100%) during primary and secondary maternal syphilis. Untreated maternal syphilis results in stillbirth or perinatal death in 40% of cases.

Clinical Presentation

Early congenital syphilis (presenting before 2 years of age) features hepatosplenomegaly, jaundice, "snuffles" (copious and often bloody nasal discharge that is highly infectious), maculopapular rash of the palms and soles with desquamation, osteochondritis and periostitis causing the painful pseudoparalysis of Parrot, hemolytic anemia, thrombocytopenia, and nephrotic syndrome. Many infants are asymptomatic at birth.

Late congenital syphilis (manifesting after 2 years if untreated) produces the Hutchinson triad of notched incisors (Hutchinson teeth), interstitial keratitis, and eighth cranial nerve deafness. Additional late findings include saddle nose deformity, frontal bossing, saber shins, and Clutton joints (bilateral knee effusions).

Diagnosis

Maternal screening uses a nontreponemal test (RPR or VDRL) confirmed by a treponemal test (FTA-ABS). The neonatal workup for inadequately treated or untreated maternal syphilis includes infant RPR/VDRL with comparison of titers to maternal levels, CBC, hepatic panel, CSF analysis (VDRL, cell count, protein) for neurosyphilis evaluation, long bone radiographs for periostitis and osteochondritis, ophthalmologic examination, and auditory brainstem response testing.

Treatment

Treatment consists of aqueous crystalline penicillin G at 50,000 units/kg IV every 12 hours for infants younger than 7 days or every 8 hours for infants older than 7 days, continued for 10 days. Alternatively, procaine penicillin G at 50,000 units/kg IM daily for 10 days may be used. Follow-up requires serial nontreponemal titers, which should decline and become nonreactive by 6-12 months. CSF should be re-examined at 6 months if the initial analysis was abnormal.

TORCH Infections Summary

Congenital Zika Virus

Zika virus is a mosquito-borne flavivirus recognized since the 2015-2016 epidemic as a cause of congenital Zika syndrome. The syndrome features severe microcephaly with partially collapsed skull, subcortical calcifications, macular scarring, congenital contractures (arthrogryposis), and marked neurologic impairment. Diagnosis relies on Zika RNA PCR and Zika IgM in infant serum and CSF. No specific treatment exists; management is supportive with neurodevelopmental follow-up. Prevention centers on vector control and avoidance of travel to endemic areas during pregnancy.

Clinical Pearls

Congenital infection should always be considered in any newborn with unexplained thrombocytopenia, hepatosplenomegaly, conjugated hyperbilirubinemia, or intrauterine growth restriction. The pattern of intracranial calcifications helps narrow the differential: periventricular suggests CMV, diffuse and scattered suggests toxoplasmosis, and basal ganglia calcifications suggest Zika. CMV testing must be performed within the first 21 days of life to confirm congenital rather than postnatal infection, and this window is frequently missed in clinical practice. Congenital syphilis is entirely preventable with adequate maternal screening and treatment, and its resurgence reflects failures in prenatal care access. In congenital HSV, the absence of skin vesicles does not rule out CNS or disseminated disease. Ordering "TORCH titers" as a blanket panel is wasteful; targeted testing based on the clinical presentation is preferred.

<image>Comparison of intracranial imaging findings across TORCH infections showing periventricular calcifications in CMV, diffuse scattered calcifications in toxoplasmosis, basal ganglia calcifications and severe microcephaly in Zika, and normal-appearing brain with potential cortical malformations in rubella</image>

Key Controversy: Universal Newborn CMV Screening

Congenital CMV is common (0.5-1% prevalence) and is the leading cause of non-genetic sensorineural hearing loss, yet 85-90% of infected infants are asymptomatic at birth and 10-15% of these will develop late-onset hearing loss. Current screening relies on targeted testing of symptomatic infants, missing the majority of affected newborns.

Arguments for universal screening include early identification allowing audiologic monitoring and intervention, potential to prevent hearing deterioration with early valganciclovir treatment, and the possibility of mitigating SNHL outcomes. Arguments against include the absence of proven treatment benefit for asymptomatic congenital CMV (though trials are underway), false-positive saliva screening from breast milk contamination, parental anxiety from identification without a clear treatment pathway, cost and feasibility challenges of screening millions of newborns, and the logistic difficulty of ensuring testing within the 21-day diagnostic window.

Several states including Minnesota, Connecticut, and Utah have implemented targeted or universal screening programs. Active clinical trials such as ValEAR are investigating valganciclovir for asymptomatic congenital CMV with isolated sensorineural hearing loss.

References

• Kimberlin DW, et al. Valganciclovir for Symptomatic Congenital CMV Disease. N Engl J Med. 2015;372:933-943.
• Kimberlin DW, et al. Oral Acyclovir Suppression and Neurodevelopment after Neonatal Herpes. N Engl J Med. 2011;365:1284-1292.
• Maldonado YA, et al. Congenital CMV Infection. Pediatrics. 2017;139(1):e20163430 (AAP Clinical Report).
• Dobson SR, et al. Congenital Toxoplasmosis Treatment Study. Pediatrics. 2020;145(4):e20193879.
• CDC. Sexually Transmitted Infections Treatment Guidelines: Congenital Syphilis. 2021.
• Rasmussen SA, et al. Zika Virus and Birth Defects. N Engl J Med. 2016;374:1981-1987.
• Rawlinson WD, et al. Congenital CMV Infection in Pregnancy and the Neonate. Lancet Infect Dis. 2017;17(6):e177-e188.

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