A newborn presents with microcephaly, cataracts, and chorioretinitis. The mother had a mild illness with rash during the first trimester. What is the most likely causative virus?

• A. Cytomegalovirus
• B. HIV
• C. Rubella virus
• D. Measles virus

Answer: (C)

The clinical presentation of the newborn, including microcephaly, cataracts, and chorioretinitis, strongly suggests congenital rubella syndrome. The mother’s report of a mild illness with rash during the first trimester aligns well with rubella infection, as maternal infection during early pregnancy can lead to significant teratogenic effects on the fetus.

Rubella virus is known for its association with the classic triad of congenital defects: cardiac abnormalities, cataracts, and sensorineural hearing loss. Microcephaly can also occur as part of this syndrome. The timing of maternal infection plays a crucial role in determining the likelihood of these congenital abnormalities. The first trimester is particularly critical, as this is when the fetus is most susceptible to the teratogenic effects of the rubella virus.

In contrast, while cytomegalovirus may also cause microcephaly and chorioretinitis, it is less commonly associated with cataracts. HIV can lead to various neonatal complications, but it is not typically linked to this specific triad of findings. Measles virus is associated with severe illness in children but does not lead to this constellation of abnormalities when contracted by the mother during pregnancy. Thus, the combination of the maternal history, symptoms, and the