Question
Name four organisms causing congenital infections and describe in detail any one of them. (4+4)
Answer
Four organisms causing congenital infections (the classical “TORCH” group and related agents):
- Toxoplasma gondii.
- Rubella virus.
- Cytomegalovirus (CMV).
- Herpes simplex virus (and Treponema pallidum, causing congenital syphilis, is another important classical example).
Detailed description — Congenital Rubella Syndrome (CRS)
Transmission: Rubella virus infection acquired by a non-immune pregnant woman, particularly during the first trimester (when the risk and severity of fetal damage is highest, given the teratogenic effect during the critical period of organogenesis), crosses the placenta and infects the developing fetus.
Clinical manifestations (classical triad and expanded features):
- Cardiac defects — particularly Patent Ductus Arteriosus (PDA) and pulmonary artery stenosis.
- Ocular defects — congenital cataract, glaucoma, retinopathy.
- Sensorineural deafness — the most common single manifestation.
- Additional features: microcephaly, intrauterine growth restriction, hepatosplenomegaly, “blueberry muffin” rash (dermal erythropoiesis), and developmental/intellectual disability, in more severely affected infants.
Laboratory diagnosis:
- Detection of rubella-specific IgM antibody in neonatal/infant serum (since maternal IgM does not cross the placenta, its presence in the infant confirms congenital infection).
- Persistently elevated/rising rubella IgG titre beyond the expected decline of passively transferred maternal antibody.
- Virus isolation or RT-PCR — detection of viral RNA from throat swab, urine, or CSF, particularly useful in the first months of life, since infants with CRS may shed virus for a prolonged period, posing an infection-control consideration.
Prevention: MMR (Measles-Mumps-Rubella) vaccination, ideally ensuring women of childbearing age are immune (either via vaccination or documented prior immunity) before pregnancy, since the vaccine (a live attenuated vaccine) is contraindicated during pregnancy itself; screening of pregnant women for rubella immunity is part of standard antenatal care in many settings.