CONGENITAL INTRAUTERINE INFECTIONS

Congenital Intrauterine Infections

Congenital intrauterine infections refer to infections transmitted from mother to fetus during pregnancy, leading to fetal or neonatal disease. These infections can result in miscarriage, stillbirth, preterm birth, intrauterine growth restriction (IUGR), congenital anomalies, or long-term neurodevelopmental impairment. Early diagnosis and timely management are crucial to minimize adverse outcomes.

Traditionally, congenital infections are grouped under the acronym TORCH, which includes Toxoplasmosis, Rubella, Cytomegalovirus infection, and Herpes simplex, along with other infections such as syphilis, varicella, parvovirus B19, HIV, hepatitis B, and Zika virus.

Pathogenesis and Transmission

Intrauterine infections occur primarily through transplacental transmission during maternal viremia or parasitemia. Some infections ascend from the genital tract, while others may be transmitted during delivery. The severity of fetal damage depends on:

• Gestational age at infection

• Virulence of the organism

• Maternal immune status

• Duration of fetal exposure

Infections during the first trimester often cause structural malformations, while later infections may result in growth restriction, organ dysfunction, or preterm birth.

Major Congenital Infections

1. Toxoplasmosis

Caused by the protozoan Toxoplasma gondii, maternal infection typically occurs through ingestion of undercooked meat or exposure to cat feces. Fetal infection may result in the classic triad:

• Chorioretinitis

• Hydrocephalus

• Intracranial calcifications

Severity is greater when infection occurs early in pregnancy. Treatment during pregnancy may reduce fetal transmission and severity.

2. Rubella

Maternal infection with rubella virus in early pregnancy can cause congenital rubella syndrome (CRS). Features include:

• Sensorineural deafness

• Cataracts

• Congenital heart defects (e.g., PDA)

• Microcephaly

Vaccination prior to pregnancy has significantly reduced incidence worldwide.

3. Cytomegalovirus (CMV)

CMV is the most common congenital viral infection. Many infants are asymptomatic at birth, but symptomatic cases may present with:

• Periventricular calcifications

• Microcephaly

• Hepatosplenomegaly

• Thrombocytopenia

• Developmental delay

Primary maternal infection carries the highest risk of fetal transmission.

4. Herpes Simplex Virus (HSV)

HSV transmission usually occurs during delivery, but intrauterine infection is rare and may cause:

• Skin vesicles or scarring

• Eye involvement

• Central nervous system damage

Cesarean delivery is recommended in women with active genital lesions at labor.

5. Syphilis

Untreated maternal syphilis can lead to congenital syphilis, characterized by:

• Hepatosplenomegaly

• Rash

• Bone abnormalities

• Late manifestations such as Hutchinson teeth and saddle nose deformity

Screening during pregnancy and penicillin therapy effectively prevent fetal complications.

Clinical Manifestations

Common features of congenital intrauterine infections include:

• Intrauterine growth restriction (IUGR)

• Prematurity

• Low birth weight

• Microcephaly

• Seizures

• Hepatosplenomegaly

• Jaundice

• Thrombocytopenia

• Intracranial calcifications

Some infants appear normal at birth but develop hearing loss, vision problems, or neurodevelopmental delay later in childhood.

Diagnosis

Diagnosis involves maternal and fetal evaluation:

Maternal testing:

• Serology (IgM and IgG antibodies)

• Avidity testing to determine timing of infection

• PCR assays for viral DNA

Fetal assessment:

• Ultrasound for structural abnormalities (hydrocephalus, calcifications, ascites)

• Amniocentesis for PCR testing

• Doppler studies in selected infections

Neonatal evaluation:

• Blood tests

• CSF examination

• Neuroimaging

• Ophthalmologic and hearing assessment

Management

Management depends on the specific infection:

• Antiparasitic therapy for toxoplasmosis

• Antiviral therapy (e.g., ganciclovir) for symptomatic CMV

• Penicillin for syphilis

• Supportive neonatal care

Prevention is a key strategy and includes:

• Preconception vaccination (e.g., rubella)

• Routine antenatal screening (e.g., syphilis, HIV, hepatitis B)

• Safe food practices

• Avoiding exposure to infectious agents

• Screening and counseling in high-risk pregnancies

Prevention and Public Health Importance

Congenital infections remain a significant cause of perinatal morbidity and mortality worldwide. Vaccination programs, antenatal screening policies, improved sanitation, and public awareness have reduced incidence in many regions. However, emerging infections such as Zika virus highlight the ongoing need for surveillance and preventive strategies.