The TORCH screen is a group of blood tests that check for several different infections in a newborn. TORCH stands for toxoplasmosis, rubella, cytomegalovirus, herpes simplex Toxoplasma gondii:

Toxoplasma:

Toxoplasma gondii is an obligate intracellular protozoan parasite that is capable of infecting a variety of intermediate hosts including humans. Toxoplasmosis is acquired by humans through ingestion of food or water contaminated with cat feces or through eating undercooked meat containing viable oocysts. Vertical transmission of the parasite through the placenta can also occur, leading to congenital Toxoplasmosis. Following primary infection, Toxoplasma gondii can remain latent for the life of the host; the risk for reactivation is highest among immunosuppressed individuals.

Transplacental transmission of the parasites resulting in congenital toxoplasmosis can occur during the acute phase of acquired maternal infection. The risk of fetal infection is a function of the time at which acute maternal infection occurs during gestation.

 The incidence of congenital toxoplasmosis increases as pregnancy progresses; conversely, the severity of congenital toxoplasmosis is greatest when maternal infection is acquired early during pregnancy.

Rubella:

Rubella (German or 3-day measles) is a member of the togavirus family and humans remain the only natural host for this virus in utero rubella infections can lead to severe sequelae for the fetus, particularly if infection occurs within the first 4 months of gestation. Congenital rubella syndrome is often associated with hearing loss, cardiovascular and ocular defects.

cytomegalovirus: 

cytomegalovirus is a common herpes virus. Many people do not know they have it, because they may have no symptoms. But the virus, which remains dormant in the body, can cause complications during pregnancy and for people with a weakened immune system.

90 percent of babies born with CMV have no symptoms, but 10 percent to 15 percent of them will develop hearing loss, normally during their first 6 months of life. The severity ranges from slight to total hearing loss.

 75 percent of babies born with congenital CMV, there will be an impact on the brain.  Conditions that they may face include:  Autism، Central vision loss, scarring of the retina, and uveitis, or swelling and irritation of the eye ، Cognitive and learning difficulties ،Deafness or partial hearing loss، Epilepsy، Impaired vision،Problems with physical coordination

HSV:

HSV types 1 and 2 are members of the Herpesviridae, and produce infections that may range from mild stomatitis to disseminated and fatal disease.

Clinical conditions associated with HSV infection include gingivostomatitis, keratitis, encephalitis, vesicular skin eruptions, aseptic meningitis, neonatal herpes, genital tract infections, and disseminated primary infection.