What is a TORCH (Toxoplasmosis, Other, Rubella, Cytomegalovirus, Herpes simplex virus) infection?

What is a TORCH Infection?

TORCH is an acronym representing a group of congenital and perinatal infections that can cause serious fetal and neonatal harm, including: Toxoplasmosis, Other infections (syphilis, varicella-zoster, parvovirus B19, hepatitis B, Zika virus), Rubella, Cytomegalovirus (CMV), and Herpes simplex virus (HSV). 1, 2

Core Components of TORCH

The TORCH acronym encompasses specific pathogens that share common features:

• T = Toxoplasmosis: Caused by Toxoplasma gondii, a parasitic infection transmitted primarily through contaminated food, water, or soil, or by ingesting undercooked meat containing tissue cysts 3, 4
• O = Other infections: Includes syphilis (Treponema pallidum), varicella-zoster virus, parvovirus B19, hepatitis B and C viruses, human immunodeficiency virus (HIV), Zika virus, and enteroviruses 1, 5, 6
• R = Rubella: Rubella virus infection during pregnancy 1, 2
• C = Cytomegalovirus (CMV): The most common congenital viral infection 2, 5
• H = Herpes simplex virus: Both HSV-1 and HSV-2 1, 2

Why TORCH Infections Matter Clinically

These infections are grouped together because they share critical clinical characteristics:

• Similar clinical presentations: Newborns may present with rash, hepatosplenomegaly, jaundice, thrombocytopenia, microcephaly, intracranial calcifications, chorioretinitis, and hearing loss 3, 5
• Maternal transmission during pregnancy: All can be transmitted from mother to fetus during pregnancy or perinatally, with devastating consequences 3, 7
• Often asymptomatic in mothers: The majority of infected pregnant women show no symptoms, making screening and high clinical suspicion essential 3, 8
• Severe fetal/neonatal outcomes: These infections are major contributors to prenatal, perinatal, and postnatal morbidity and mortality, particularly in low- and middle-income countries 1

Clinical Manifestations in Neonates

At Birth

• 70-90% of infected infants are asymptomatic at birth for many TORCH infections, particularly toxoplasmosis 3, 4, 7
• When symptomatic, neonates may present with generalized disease (maculopapular rash, lymphadenopathy, hepatosplenomegaly, jaundice, anemia, thrombocytopenia) or predominantly neurologic disease (hydrocephalus, intracranial calcifications, microcephaly, chorioretinitis, seizures) 3

Late Sequelae

• The majority of asymptomatic children develop late complications including retinitis, visual impairment, hearing loss, and intellectual or neurologic impairment, with onset ranging from months to years after birth 3, 4, 7

Specific Risk in Immunocompromised Patients

TORCH infections pose particular danger in specific populations:

• HIV-infected pregnant women: At increased risk for transmitting Toxoplasma gondii to their fetuses, with transmission rates <4% even in chronically infected women due to reactivation with severe immune suppression 3
• Transplant recipients: The fetus is at risk for CMV and HSV infections related to the immunosuppressive state of the mother 3
• Fetuses exposed during pregnancy: Risk of transmission and severity varies by gestational age and specific pathogen 3

Diagnostic Approach

When TORCH infection is suspected:

• Serologic testing is the primary diagnostic method, though interpretation is often complex and requires reference laboratory expertise 3, 4
• For suspected toxoplasmosis exposure: Complete evaluation must include Toxoplasma-specific IgM, IgA, or IgE testing, ophthalmologic examination for chorioretinitis, neurologic examination, lumbar puncture for CSF analysis, and head imaging for hydrocephalus or intracranial calcifications 7
• For HSV: Obtain cultures from blood, skin vesicles, mouth/nasopharynx, eyes, urine, and stool/rectum immediately, plus CSF HSV PCR (gold standard for neonatal HSV encephalitis) 7
• Timing matters: Only 60% of neonates with CNS or disseminated HSV disease present with vesicular rash—absence of skin lesions should not delay evaluation 7

Prevention and Treatment Considerations

• Primary prevention of maternal infections during pregnancy is the cornerstone of preventing congenital infection 5
• Early recognition through prenatal screening is key, as treatment or prevention strategies are available for many of these pathogens 1
• For toxoplasmosis: Prompt initiation of prenatal treatment as soon as possible after acute maternal infection decreases mother-to-child transmission and ameliorates severity 3
• For HSV: IV acyclovir is the treatment of choice, with dosing and duration dependent on disease extent (CNS/disseminated vs. localized) 7