Vertically transmitted infection

A vertically transmitted infection is an infection caused by pathogenic bacteria or viruses that use mother-to-child transmission, that is, transmission directly from the mother to an embryo, fetus, or baby during pregnancy or childbirth. It can occur when the mother has a pre-existing disease or becomes infected during pregnancy. Nutritional deficiencies may exacerbate the risks of perinatal infections. Vertical transmission is important for the mathematical modelling of infectious diseases, especially for diseases of animals with large litter sizes, as it causes a wave of new infectious individuals. Bacteria, viruses, and other organisms are able to be passed from mother to child. Several vertically transmitted infections are included in the TORCH complex: T – toxoplasmosis from Toxoplasma gondii O – other infections (see below) R – rubella C – cytomegalovirus H – herpes simplex virus-2 or neonatal herpes simplex Other infections include: Parvovirus B19 Coxsackievirus Chickenpox (caused by varicella zoster virus) Chlamydia HIV Human T-lymphotropic virus Syphilis Zika fever, caused by Zika virus, can cause microcephaly and other brain defects in the child. COVID-19 in pregnancy is associated with an increased risk of stillbirth with an odds ratio of approximately 2. Hepatitis B may also be classified as a vertically transmitted infection. The hepatitis B virus is large and does not cross the placenta. Hence, it cannot infect the fetus unless breaks in the maternal-fetal barrier have occurred, but such breaks can occur in bleeding during childbirth or amniocentesis. The TORCH complex was originally considered to consist of the four conditions mentioned above, with the "TO" referring to Toxoplasma. The four-term form is still used in many modern references, and the capitalization "ToRCH" is sometimes used in these contexts. The acronym has also been listed as TORCHES, for TOxoplasmosis, Rubella, Cytomegalovirus, HErpes simplex, and Syphilis.