TORCH

• Toxoplasmosis is a parasitic infection that can be passed from mother to baby through the placenta during pregnancy. Infection with Toxoplasma gondii can cause disease of the eye and central nervous system, as well as cysts in muscle and brain. If a woman catches toxoplasmosis during pregnancy, miscarriage or birth defects are possible, depending on when the mother comes into contact with the parasite. Toxoplasmosis is caught by swallowing the parasite when handling infected cat faeces, drinking unpasteurised goat’s milk and, most commonly, eating contaminated meat.

• Rubella is the virus that causes German measles. If it is caught early in pregnancy, the baby may develop heart disease, slowed growth, hearing loss, blood disorders, vision problems or pneumonia. Effects that may appear during childhood include central nervous system disease, immune system disorders and thyroid disease.

• Cytomegalovirus (CMV) is another viral infection that a woman can catch during pregnancy. More than half of Italian adults have been infected with CMV at some point in their lives, but in most cases it does not cause serious illness. It can pass to the baby during delivery and can also infect the newborn through breast milk. Infected newborns may have serious problems such as hearing loss, intellectual disability, pneumonia, hepatitis or blood disorders.

• Herpes simplex virus (HSV) is a common viral infection. The two most common HSV infections are “cold sores”, which affect the lips, and genital herpes. A person can have both infections. HSV is commonly spread by oral or genital contact. Newborns usually catch the virus while passing through the birth canal when the mother has a genital HSV infection. The virus can spread throughout the newborn’s body, attacking vital organs. Treatment with specific antiviral drugs must begin as soon as possible in an infected newborn. Even after treatment, babies who survive may suffer permanent damage to the central nervous system.

Other infections that may be tested for at the same time are syphilis, hepatitis B, human immunodeficiency virus (HIV), enterovirus, Epstein-Barr virus, varicella-zoster virus and human parvovirus.

How is the sample collected for testing?
The sample is a simple blood test from a vein in the arm or, in newborns, from the heel.

Is any preparation needed to ensure the quality of the sample?
No preparation is needed for the test.

1. How is it used?
The TORCH test is used to check for antibodies produced in response to the infectious diseases included in the panel; it is performed mainly for pregnant women and for newborns with symptoms that may be due to these infections. The blood test shows whether a person has had a recent infection or a past infection, or has never been exposed to the pathogen.

2. When is it requested?
The test is requested when a pregnant woman is suspected of having one of the infections included in the TORCH panel. These infections can become serious if they occur during pregnancy, because the pathogens can cross the mother’s placenta, pass to the fetus and cause birth defects in the baby.
Rubella infection during the first 16 weeks of pregnancy carries the greatest risk for the baby. When a pregnant woman has a rash and other symptoms that may be due to rubella infection, laboratory tests are needed to reach a correct diagnosis. The doctor cannot rely solely on the clinical picture, which is shared with other types of infection. With Toxoplasma or CMV too, the symptoms are similar to those of other illnesses such as flu. Antibody testing will therefore help the doctor diagnose an infection that may harm the baby.

The test may be requested for a newborn baby showing some typical signs of these infections, such as:

• unusually small size for gestational age,
• deafness
• intellectual disability,
• seizures
• heart defects,
• cataracts
• enlarged liver or spleen,
• low platelet count
• jaundice

3. What does the result mean?
Results are usually reported as positive or negative, indicating the presence or absence of IgG and IgM antibodies to each infectious agent. Because IgM antibodies produced by the mother cannot cross the placenta, IgM antibodies in a newborn very probably indicate an active infection in the baby. By contrast, IgG antibodies without IgM in a newborn may indicate passive transfer of maternal antibodies rather than an active infection.
Similarly, IgM antibodies in a pregnant woman suggest a new infection with the virus or parasite. Further tests must, however, be carried out to confirm the diagnosis, as IgM antibodies may be present for other reasons. IgG antibodies in a pregnant woman may result from a previous infection with one of the agents tested for. By testing a second blood sample taken two weeks later, antibody levels can be compared: if the second sample shows an increase in IgG antibodies, a recent infection with the agent in question is likely.

4. Is there anything else I should know?
The TORCH panel has become less commonly used to diagnose these infections now that more specific and sensitive tests are available. Antibody production after infection takes days to weeks, and waiting for antibodies to become detectable would delay the diagnosis. Detecting antigens or growing the organism in culture can be done early in the infection and is more specific.
Pregnant women and newborns are often tested for other infectious diseases, such as syphilis, hepatitis B, human immunodeficiency virus (HIV), enterovirus, Epstein-Barr virus, varicella-zoster virus and human parvovirus. For more information, see Pregnancy and Newborn screening tests; Infectious diseases

1. If my antibody test is positive, does it mean I have been infected?
A positive IgG antibody test may indicate either a current infection or a past infection that has cleared. If the blood sample was taken when the illness began, a positive IgG result probably means that you were exposed to the agent more than a month ago, possibly even years before the current illness. By comparing the amount of antibody in two blood samples taken 2-3 weeks apart, the doctor can tell whether IgG levels are rising (associated with a recent infection) or stable (associated with a past infection). A positive IgM antibody test is harder to interpret, as false positives can occur. Some positive results should be confirmed with additional specific tests before the diagnosis can be considered valid. If your doctor suspects that you or your baby may have one of these infections despite a negative antibody test, other tests should be carried out to make sure that there is really no infection.

2. What type of test is used to confirm infection with these organisms?
To diagnose an active infection with one of the pathogens in the TORCH panel, more specific confirmatory tests must be carried out. In a baby, cerebrospinal fluid testing (which requires a lumbar puncture) is often used to confirm toxoplasmosis, herpes and rubella; a urine culture can be done for cytomegalovirus; for herpes simplex virus, if there are skin lesions, material obtained by gently scraping the surface of the lesion can be cultured. To diagnose toxoplasmosis in a pregnant woman or a baby, additional blood samples may be needed, which will be sent to a specialist reference laboratory for this test