What are the effects of TORCH (Toxoplasmosis, Rubella, Cytomegalovirus, Herpes simplex virus) and CLAP (Chlamydia, Lyme disease, AIDS, Parvovirus B19) infections, as well as Zika and COVID-19, on a fetus in a pregnant individual or someone of childbearing age?

Fetal Effects of TORCH, CLAP, Zika, and COVID-19 Infections

Each of these maternal infections carries distinct risks for the fetus, ranging from severe congenital anomalies and microcephaly (Toxoplasmosis, Rubella, CMV, Zika) to increased preterm birth and stillbirth (COVID-19, HSV), with most causing mild maternal symptoms but potentially devastating fetal consequences that require vigilant monitoring and counseling on prevention.

TORCH Infections

Toxoplasmosis

• Causes congenital anomalies in 2-3% of all cases when transmitted vertically 1
• Produces serious fetal consequences despite causing only mild maternal morbidity 1
• Treatment of maternal infection frequently has no impact on fetal outcome, making prevention critical 1

Rubella

• Results in congenital rubella syndrome with cardiac defects, cataracts, and deafness 1
• Associated with long-term sequelae including autism and adult-onset diabetes 2
• Maternal infection causes mild symptoms but severe fetal developmental disruption 1

Cytomegalovirus (CMV)

• Most common congenital infection causing sensorineural hearing loss and developmental delays 1
• Hearing loss can develop during the first year of life even when absent at birth 2
• Produces variable outcomes from asymptomatic infection to severe neurologic impairment 3

Herpes Simplex Virus (HSV)

• Causes neonatal herpes with high mortality if disseminated or involving CNS 1
• Transmission primarily occurs during delivery rather than in utero 1
• Maternal infection requires careful monitoring and consideration of cesarean delivery 1

CLAP Infections

Chlamydia

• Leads to neonatal conjunctivitis and pneumonia through vertical transmission during delivery 3
• Does not typically cause congenital anomalies but increases risk of preterm birth 3

Lyme Disease

• Limited evidence for significant fetal effects, though vertical transmission has been reported 3
• Appropriate antibiotic treatment during pregnancy is essential 3

AIDS (HIV)

• Without treatment, vertical transmission occurs in 25-30% of cases 3
• Antiretroviral therapy during pregnancy reduces transmission to less than 2% 3
• Requires comprehensive prenatal care and delivery planning 3

Parvovirus B19

• Causes fetal hydrops and severe anemia through infection of erythroid precursor cells 1, 3
• Can lead to fetal demise, particularly in second trimester infections 1
• Maternal infection often presents as mild illness or fifth disease 3

Zika Virus

Zika virus is definitively teratogenic and should be considered a TORCH pathogen 4, 5

• Causes congenital Zika syndrome (CZS) characterized by severe microcephaly, brain anomalies, and eye defects 2, 4
• Microcephaly may not be present at birth but can develop postnatally, with 11 of 13 infants in one series developing postnatal microcephaly by one year 2
• Virus can continue replicating in infant brain tissue after birth, causing progressive neurologic damage 2
• Eye findings occur even in infants without microcephaly or brain anomalies 2
• Delays in recognizing high fetal morbidity and mortality during the outbreak led to preventable harm 2
• Long-term effects include developmental delays, sensory impairments, and motor dysfunction requiring years of monitoring 2

COVID-19 (SARS-CoV-2)

COVID-19 in pregnancy is associated with increased severe maternal and neonatal morbidity, including preeclampsia, preterm birth, cesarean delivery, and low birthweight infants 2

Direct Fetal Effects

• Vertical transmission appears rare but documented, with unclear mechanisms of placental transfer 2
• Placental pathology shows inflammation, thrombosis, and vascular malperfusion 2
• Outcomes include preterm birth, stillbirth, intrauterine fetal demise (IUFD), and neonatal death 2

Indirect Fetal Effects

• Maternal inflammatory state, hypoxia, and thrombotic disease impact fetal developmental pathways 2
• Potential for alterations in stress pathways, fetal inflammatory response syndrome, and epigenetic changes 2
• Long-term neurodevelopmental effects remain unknown but concerning given inflammatory cytokine release 6
• Placental dysfunction from inflammation or thrombosis can cause intrauterine growth restriction (IUGR) and hypoxia 6
• Increased risk of cognitive and behavioral issues such as ADHD or autism from inflammatory cytokine exposure 6

Maternal Disease Severity

• Pregnant individuals experience equal or more severe disease than nonpregnant individuals 2
• Black and Hispanic pregnant individuals are disproportionately affected 2
• Maternal morbidity and mortality risks were initially underestimated due to reporting bias 2

Critical Clinical Considerations

Prevention and Counseling

• Recognition of maternal disease and appropriate counseling on preventive measures are essential since treatment often cannot alter fetal outcomes 1
• Hand hygiene for at least 20 seconds, avoiding sharing utensils, and cleaning surfaces reduce transmission 7
• Vaccination when available (rubella, COVID-19) is critical for prevention 2

Monitoring Requirements

• Fetal monitoring once maternal disease is recognized is crucial for all clinicians 1
• Long-term developmental surveillance is necessary for years, as some conditions are absent or difficult to detect at birth 2
• Serial ultrasounds to assess fetal growth and anatomy are indicated 2

Common Pitfalls

• Assuming absence of findings at birth excludes future problems—many effects manifest later in infancy or childhood 2
• Underestimating risks based on early case reports during emerging pandemics due to censoring bias 2
• Failing to recognize that asymptomatic maternal infections can still cause severe fetal disease 1, 5