Your primary dx should be the sign/symptom or diagnosis that drove the encounter. This may or may not be the presenting problem. (ie pt presents with pharyngitis, but due to pain has not been drinking fluids. Labs indicate dehydration, for which an IV of fluids is started and he/she is admitted overnight.
Neurosyphilis is considered infectious but is not transmitted from person to person. Generally, a disease like this is caused by an infectious agent and not spread between people. Neurosyphilis, although infectious, is not a genetic disease. It is not caused by a defective or abnormal gene.
Syphilis is a contagious infection caused by Treponema pallidum and is primarily transmitted through sexual contact. However, if you are an expecting mother with syphilis congenital syphilis is also a possibility. Congenital syphilis results through transplacental transmission of the bacteria to the baby. Transmission is possible at any stage of pregnancy and can result in death, or multiple organ problems, it can also affect ears, eyes, liver, bone marrow, skin, bones, and heart.