What is the most likely causative agent for the symptoms of a small-for-gestational age infant with chorioretinitis and jaundice?

The selection of cytomegalovirus (CMV) as the most likely causative agent for the symptoms in a small-for-gestational-age infant is supported by the association between CMV infection and both chorioretinitis and jaundice. CMV is one of the leading infectious causes of congenital defects, and it is known to cause a range of symptoms in affected infants, including growth restriction, neurologic issues, and specific ocular manifestations such as chorioretinitis.

Infants with congenital CMV infection often present with a distinctive set of clinical findings, which can include microcephaly, jaundice due to liver dysfunction, and retinal damage indicative of chorioretinitis. This combination of symptoms—being small for gestational age, having chorioretinitis, and jaundice—points most directly to CMV as the underlying cause.

Other potential infectious agents listed can cause symptoms in neonates as well, but they are less common in this specific combination of findings. Toxoplasmosis, rubella, and Zika virus can lead to congenital infection and some overlapping symptoms, yet they do not typically present with the same frequency or severity of chorioretinitis and jaundice as seen with CMV. For example, while tox