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TORCH Test

TORCH test

Definition

The TORCH test, sometimes called the TORCH panel, belongs to a category of blood tests called infectious-disease antibody titers. A titer is the serial dilution of antibodies (protein molecules or immunoglobulins produced by the immune system in response to specific disease agents) found in blood serum that determines their level of concentration. Antibodies are proteins produced by the immune system in response to infectious agents that are foreign to the body, such as viruses, bacteria, parasites, or toxins. These infectious organisms have antigens on their surfaces that stimulate the immune system to produce corresponding antibodies. IgM antibodies are produced in response to viruses. The TORCH test screens for the presence of IgM antibodies, and the titer determines their concentration in the blood. The name of the test is an acronym derived from the initial letters of the five groups of chronic infections: toxoplasmosis , other viruses, rubella , cytomegalovirus (CMV), and herpes simplex virus (HSV). The "other viruses" usually include syphilis, hepatitis B , coxsackie virus, Epstein-Barr virus (mononucleosis), varicella-zoster virus, and human parvovirus. The test is performed by various methods in the clinical laboratory and may also be referred to as viral immunoglobulins testing. Methods used in the early 2000s are more sensitive and specific and can identify the specific virus.

Purpose

A TORCH test is performed to help screen for certain virus infections in infants who may have been exposed to a causative organism. The five groups of disease-causing organisms whose antibodies are measured by the TORCH test are grouped together because they can cause a cluster of symptomatic birth defects in newborns. This group of defects is sometimes called the TORCH syndrome. The pediatrician may order the TORCH test to be performed when a newborn has these symptoms, in order to determine if any of the five types of infection may be involved.

Symptoms of TORCH syndrome that may encourage testing include the following:

  • Small size in proportion to length of the mother's pregnancy at time of delivery: Infants who are smaller than would be expected (below the tenth percentile) are referred to as small-for-gestational-age (SGA).
  • Enlarged liver and spleen.
  • Low level of platelets (tiny cellular elements in blood that are an important part of coagulation).
  • Skin rash: The type of skin rash associated with the TORCH syndrome is usually reddish-purple or brown and is caused by the leakage of blood from broken capillaries into the baby's skin.
  • Central nervous system impairment: This may include encephalitis , calcium deposits in brain tissue, or seizures.
  • Jaundice : Yellow-stained skin and whites of the eyes due to elevated levels of bilirubin, a substance normally filtered out by the liver. Jaundice may indicate liver dysfunction, although it can also be a normal result of red cell turnover in the newborn.

Description

Besides general symptoms that may encourage a pediatrician to order the TORCH panel of tests, each of the TORCH infections has its own origins and may have a characteristic cluster of symptoms in newborns. These unique characteristics, the general condition and symptoms of the child, and the test results are studied in order for the physician to make a diagnosis.

Toxoplasmosis

Toxoplasmosis is caused by Toxoplasma gondii, a parasite that can be acquired by the mother from handling cat feces, drinking unpasteurized milk, or eating contaminated meat. The infection is carried to the infant through the mother's placenta and can cause impairment of the infant's eyes (opthalmic impairment) and central nervous system (neurological dysfunction). The organism can invade brain or muscle tissue and form cysts. Infection acquired by the mother later in pregnancy usually decreases the likelihood of infection in the infant at birth although eye problems may occur in adolescence . Toxoplasmosis early in pregnancy is more likely to cause miscarriage or serious birth defects. The incidence of toxoplasmosis in newborns is one in 1,000 live births.

Other viruses (syphilis)

Syphilis is caused by the spiral- or coil-shaped bacteria (spirochete), Treponema pallidum. It is transmitted among adults through sexual intercourse. About 2 to 5 percent of children born to mothers diagnosed with syphilis have the disease at birth. Syphilis was added to the TORCH panel because of an increase in reported cases after 1990. Syphilis can cause early delivery, miscarriage, and is a potentially life-threatening infection for an affected fetus, often resulting in stillbirth. The mortality rate in infants infected with syphilis is about 54 percent.

Rubella

Rubella is a virus that has a seasonal pattern, with epidemics most likely in the spring. Between 0.1 to 2 percent of newborns are infected with rubella. The rate of fetal infection varies according to the timing of the mother's infection during pregnancy. Birth defects, however, are most likely (85%) in infants infected during the first eight weeks of pregnancy. Infants born with rubella may already show signs of heart disease, retarded growth, hearing loss, blood disorders, vision problems, or pneumonia . They may also develop problems later in childhood, including autism , hearing loss, brain syndromes, immune system disorders, or thyroid disease.

Cytomegalovirus (CMV)

Cytomegalovirus belongs to the herpesvirus group of infections. It can be transmitted through body secretions, as well as by sexual contact; some newborns acquire CMV through the mother's breast milk. In adults, it produces symptoms resembling those of mononucleosis. About 1 to 2.2 percent of newborns in the United States are infected with CMV. Of this group, 10 percent have measurable symptoms. The mortality rate for these symptomatic newborns is 20 to 30 percent. Surviving infants with CMV may suffer from hearing problems (15%) or mental retardation (30%). Newborns who acquire CMV during the birth process or shortly after birth may develop pneumonia, hepatitis, or various blood disorders.

Herpes simplex virus (HSV)

Herpesvirus infections are among the most common viral infections in humans. They are spread by oral or genital contact. It is estimated that between one in 1,000 and one in 5,000 infants are born with HSV infections. About 80 percent of these infections are acquired during the birth process itself; the virus enters the infant through its eyes, skin, mouth, and upper respiratory tract. Of infants born with HSV infection, about 20 percent have localized infections of the eyes, mouth, or skin. About 50 percent of infected infants will develop the disease throughout the body (disseminated) within nine to 11 days after birth. Disseminated herpes infections attack the liver and adrenal glands, as well as other body organs. Without treatment, the mortality rate is 80 percent. Even with antiviral medication, the mortality rate is still 15 to 20 percent, with 40 to 55 percent of the survivors having long-term damage to the central nervous system. In order to begin early, effective treatment, it is critical for pediatricians to diagnose HSV infection in newborns as soon as possible.

Performing the TORCH panel requires obtaining a sample of the infant's blood. Samples from infants are usually obtained by the heelstick procedure when only a small quantity of blood is needed. The baby's foot is wrapped in a warm cloth for five minutes to bring blood to the surface and help it to flow more easily. The foot is then sterilized with an alcohol swab and a lancet is used to puncture the baby's heel on one side, avoiding the center of the heel to prevent inflammation of the bone. The blood sample is drawn in tiny capillary tubes, properly labeled, and taken to the laboratory for testing. In rare instances, a phlebotomist is not able to draw sufficient blood from a heel puncture, and a physician may draw venous blood from a femoral vein in the groin area or another vein larger than veins in an infant's arms.

Since the TORCH test is a screening or first-level test, the pediatrician may order tests of other body fluids or tissues to confirm the diagnosis of a specific infection. In suspected cases of toxoplasmosis, rubella, or syphilis, cerebrospinal fluid may be obtained from the infant by spinal tap in order to confirm the diagnosis. A diagnosis of CMV is usually confirmed by culturing the virus in a sample of the infant's urine. In HSV infections, tissue culture is the best method to confirm the diagnosis.

Precautions

Because toxoplasmosis can be transmitted by handling cat feces, pregnant women should avoid cleaning cat boxes or handling cats. Any suspected infection should be reported to the obstetrician so that testing for the causative parasite in the mother can be performed.

Medical personnel and family members must be aware of the possible presence of infective organisms in the infant and proper precautions taken, such as hand washing, when the infant or the infant's body fluids (blood, urine, feces) are handled.

If the infant has had blood drawn often from the same site on the heel or heels, causing scarring, inflammation, or the accumulation of tissue fluid, it may cause inaccurate test results.

False negative and false positive results can occur with the TORCH test for immunoglobulins because of cross-reacting antibodies, especially among the different types of herpes viruses.

Preparation

No special preparation, other than sterile technique by medical personnel, is required.

Aftercare

The site from which blood is withdrawn must be kept clean after the procedure and must be checked regularly for bleeding. A small adhesive patch may be used to protect the site.

Risks

The performance of the TORCH test carries no significant risk. Drawing blood for the test may involve light bleeding or bruising at the site of puncture or blood may accumulate under the puncture site (hematoma), requiring that a new location be found for subsequent tests. The infant's heel may be at risk of scarring, infection of the bone, cellulitis (inflammation of cellular tissue), small lumpy calcium deposits.

Normal results

The normal result of a TORCH panel reveals normal levels of immunoglobulin M (IgM) antibody in the infant's blood. IgM is one of five types of antibodies (protein molecules) produced by the immune system and found in blood. IgM is a specific class of antibody that seeks out virus particles. It is the most common type of immunoglobulin in newborns and, therefore, the most useful indicator of the presence of one of the TORCH virus infections.

Abnormal results

The general abnormal or "positive" result reveals high levels of IgM antibody present in the infant's blood. The test can be refined further for antibodies specific to given disease agents. The TORCH screen, however, can produce both false-positive and false-negative findings. Doctors can measure IgM levels in the infant's cerebrospinal fluid, as well as in the blood, if confirmation is needed.

Parental concerns

Parents will necessarily be concerned about the possibility of infection in the child and the amount of testing that may have to be done. Awareness of the value of the TORCH panel of tests to help confirm the presence of an infective organism and its concentration in the blood is important, especially because confirmatory tests lead to faster, more effective treatment. Medical personnel can teach parents about safe practices for handling an infant with a virus infection that can possibly spread to family members.

KEY TERMS

Antibody A special protein made by the body's immune system as a defense against foreign material (bacteria, viruses, etc.) that enters the body. It is uniquely designed to attack and neutralize the specific antigen that triggered the immune response.

Antigen A substance (usually a protein) identified as foreign by the body's immune system, triggering the release of antibodies as part of the body's immune response.

Bacteria Singular, bacterium; tiny, one-celled forms of life that cause many diseases and infections.

Titer The highest dilution of a material (e.g., serum or other body fluid) that produces a reaction in an immunologic test system. Also refers to the extent to which an antibody can be diluted before it will no longer react with a specific antigen. Also spelled titre.

Virus A small infectious agent consisting of a core of genetic material (DNA or RNA) surrounded by a shell of protein. A virus needs a living cell to reproduce.

See also Cytomegalovirus (CMV) infection; Infectious mononucleosis; Hepatitis B.

Resources

BOOKS

Beers, Mark H., and Robert Berkow, eds. The Merck Manual, 2nd home ed. West Point, PA: Merck & Co., 2004.

Cohen, Margaret, et al. Sent Before My Time: A Child Psychotherapist's View of Life on a Neonatal Intensive Care Unit. London: Karnac Books, 2003.

Moore, Keith L., et al. Before We Are Born: Essentials of Embryology and Birth Defects. Kent, UK: ElsevierHealth Sciences Division, 2002.

Roberton, N. R. C., et al. A Manual of Neonatal Intensive Care. Oxford, UK: Oxford University Press, 2002.

ORGANIZATIONS

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. Web site: <www.cdc.gov>.

WEB SITES

"TORCH Test." Joseph F. Smith Medical Library. Available online at <www.chclibary.org/micromed/00068480.html> (accessed December 2, 2004).

L. Lee Culvert Rebecca J. Frey, PhD

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TORCH Test

TORCH Test

Definition

The TORCH test, which is sometimes called the TORCH panel, belongs to a category of blood tests called infectious-disease antibody titer tests. This type of blood test measures the presence of antibodies (protein molecules produced by the human immune system in response to a specific disease agent) and their level of concentration in the blood. The name of the test comes from the initial letters of the five disease categories. The TORCH test measures the levels of an infant's antibodies against five groups of chronic infections: t oxoplasmosis, o ther infections, r ubella, c ytomegalovirus (CMV), and h erpes simplex virus (HSV). The "other infections" usually include syphilis, hepatitis B, coxsackie virus, Epstein-Barr virus, varicella-zoster virus, and human parvovirus.

Since the TORCH test is a screening or first-level test, the pediatrician may order tests of other body fluids or tissues to confirm the diagnosis of a specific infection. In the case of toxoplasmosis, rubella, and syphilis, cerebrospinal fluid may be obtained from the infant through a spinal tap in order to confirm the diagnosis. In the case of CMV, the diagnosis is confirmed by culturing the virus in a sample of the infant's urine. In HSV infections, tissue culture is the best method to confirm the diagnosis.

Purpose

The five categories of organisms whose antibodies are measured by the TORCH test are grouped together because they can cause a cluster of symptomatic birth defects in newborns. This group of defects is sometimes called the TORCH syndrome. A newborn baby with these symptoms will be given a TORCH test to see if any of the five types of infection are involved.

The symptoms of the TORCH syndrome include:

  • Small size in proportion to length of the mother's pregnancy at time of delivery. Infants who are smaller than would be expected (below the tenth percentile) are referred to as small-for-gestational-age, or SGA.
  • Enlarged liver and spleen
  • Low level of platelets in the blood
  • Skin rash. The type of skin rash associated with the TORCH syndrome is usually reddish-purple or brown and is caused by the leakage of blood from broken capillaries into the baby's skin.
  • Involvement of the central nervous system. These defects can include encephalitis, calcium deposits in the brain tissue, and seizures.
  • Jaundice. The yellowish discoloration of the skin and whites of the eyes due to liver disease.

In addition to these symptoms, each of the TORCH infections has its own characteristic symptom cluster in newborns:

Toxoplasmosis

Toxoplasmosis is caused by Toxoplasma gondii, a parasite that the mother can acquire from handling infected cats, drinking unpasteurized milk, or eating contaminated meat. The infection is carried to the infant through the mother's placenta, and can cause infections of the eyes or central nervous system. The organism can invade brain or muscle tissue and form tissue cysts. The later in pregnancy that the mother is infected, the higher the probability that the fetus will be infected. On the other hand, toxoplasmosis early in pregnancy is more likely to cause a miscarriage or serious birth defects. The incidence of toxoplasmosis in newborns is one in 1,000 live births.

Other (syphilis)

Syphilis is caused by a spirochete (spiral- or coil-shaped bacterium), Treponema pallidum. It is transmitted in the adult population by sexual intercourse. About 2-5% of children born to mothers diagnosed with syphilis will have the disease at birth. Syphilis was added to the TORCH panel because of a rapid increase in reported cases since 1990. It is also a potentially life-threatening infection for the fetus. Syphilis can cause early delivery, miscarriage, or stillbirth. The mortality rate in infants infected with syphilis is about 54%.

Rubella

Rubella is a virus that has a seasonal pattern, with epidemics most likely in the spring. Between 0.1-2% of newborns will be infected with rubella. The rate of fetal infection varies according to the timing of the mother's infection during pregnancy. Birth defects, however, are most likely (85%) in infants infected during the first eight weeks of pregnancy. Infants born with rubella may already show signs of heart disease, retarded growth, hearing loss, blood disorders, vision problems, or pneumonia. They may also develop problems later in childhood, including autism, hearing loss, brain syndromes, immune system disorders, or thyroid disease.

Cytomegalovirus (CMV)

Cytomegalovirus belongs to the herpesvirus group of infections. It can be transmitted through body secretions, as well as by sexual contact; some newborns acquire CMV through the mother's breast milk. In adults, it produces symptoms resembling those of mononucleosis. About 1-2.2% of newborns in the United States are infected with CMV. Of this group, 10% will have measurable symptoms. The mortality rate for these symptomatic newborns is 20-30%. Surviving infants with CMV may suffer from hearing problems (15%) or mental retardation (30%). Newborns that acquire CMV during the birth process or shortly after birth may develop pneumonia, hepatitis, or various blood disorders.

Herpes simplex virus (HSV)

Herpesvirus infections are among the most common viral infections in humans. They are spread by oral, as well as genital, contact. It is estimated that between 1 in 1,000 and 1 in 5,000 infants are born with HSV infections. About 80% of these infections are acquired during the birth process itself; the virus enters the infant through its eyes, skin, mouth, and upper respiratory tract. Of infants born with HSV infection, about 20% will have localized infections of the eyes, mouth, or skin. About 50% of infected infants will develop disease spread throughout the body (disseminated) within nine to 11 days after birth. Disseminated herpes infections attack the liver and adrenal glands, as well as other body organs. Without treatment, the mortality rate is 80%. Even with antiviral medication, the mortality rate is still 15-20%, with 40-55% of the survivors having long-term damage to the central nervous system. It is critical for the doctor to diagnose HSV infection in the newborn as soon as possible, for effective treatment.

Description

The TORCH panel requires a sample of the infant's blood. Samples from infants are usually obtained by the heelstick procedure when only a small quantity of blood is needed. The baby's foot is wrapped in a warm cloth for five minutes, to make the blood flow more easily. The foot is then wiped with an alcohol swab and a lancet is used to stick the baby's heel on one side. It is important to avoid the center of the heel, in order to prevent an inflammation of the bone.

Preparation

No special preparation, other than sterile technique, is required.

Risks

The only complications associated with the TORCH test are those resulting from the heelstick technique itself. These risks include scarring, infection of the bone, cellulitis (inflammation of cellular tissue), small lumpy calcium deposits, and inaccurate test results.

Normal results

The normal result would be normal levels of immunoglobulin M (IgM) antibody in the infant's blood. IgM is one of five types of protein molecules found in blood that function as antibodies. IgM is a specific class of antibodies that seeks out virus particles. In contrast to adults, IgM is the most common type of immunoglobulin in newborn children. It is, therefore, the most useful indicator of the presence of a TORCH infection.

Abnormal results

The general abnormal, or positive, finding would be high levels of IgM antibody. The test can be refined further for antibodies specific to given disease agents. The TORCH screen, however, can produce both false-positive and false-negative findings. Doctors can measure IgM levels in the infant's cerebrospinal fluid, as well as in the blood, if they want to confirm the TORCH results.

Resources

BOOKS

Levin, Myron J. "Infections: Viral & Rickettsial." In Current Pediatric Diagnosis & Treatment, edited by William W. Hay Jr., et al. Stamford: Appleton & Lange, 1997.

KEY TERMS

Antibody A protein molecule produced by the immune system that is specific to a disease agent, such as CMV and the other organisms sought by the TORCH test. The antibody combines with the organism and disables it.

Perinatal Referring to the period of time surrounding an infant's birth, from the last two months of pregnancy to the first 28 days of life. The TORCH panel tests for perinatal infections.

Small-for-gestational-age (SGA) A term used to describe newborns who are below the 10th percentile in height or weight for their estimated gestational age. The gestational age is based upon the date of the mother's last menstrual period. SGA is one of the symptoms of TORCH syndrome.

Titer The concentration of a substance in a given sample of blood or other tissue fluid.

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TORCH Test

TORCH Test

Definition

The TORCH test, which is sometimes called the TORCH panel, consists of tests for antibodies to four organisms that cause congenital infections transmitted from mother to fetus. The name of the test is an acronym for the organisms detected by this panel: Toxoplasma gondii (toxoplasmosis), rubella (German measles), cytomegalovirus (CMV), and herpes simplex virus (HSV).

Purpose

Although the four diseases are not particularly serious for adults who are exposed and treated, women who are become affected with any of these diseases during pregnancy are at risk for miscarriage, still birth, or for a child with serious birth defects and/or illness. Thus, this test is performed before or as soon as pregnancy is diagnosed to determine the mother's history of exposure to these organisms. The test is also performed on neonatal serum when the newborn presents with symptoms consistent with a congenitally acquired infection by one of the organisms above.

Precautions

TORCH screening can be associated with both false negative and false positive results. False negative IgM tests can result from IgG antibodies to the organism binding to the antigen used in the test or from immunodeficiency syndromes that reduce the antibody response to these organisms. False positive test results can result from rheumatoid, autoimmune, or heterophile antibodies in the mother's serum. When testing neonates, the IgG antibody levels may be detected as a result of prior infection or current maternal infection, and therefore does not mean the neonate is infected. Maternal antibodies to HSV and CMV may not adequately protect the fetus. TORCH screening requires blood from the mother and if needed, the neonate. The nurse or phlebotomist performing the venipuncture should observe universal precautions for the prevention of transmission of bloodborne pathogens.

Description

The TORCH panel is performed on women before or during pregnancy and on newborns if warranted by risk of infection during pregnancy. Samples from infants are usually obtained by the heelstick procedure when only a small quantity of blood is needed. The baby's foot is wrapped in a warm cloth for five minutes, to make the blood flow more easily. The foot is then wiped with an alcohol swab and a lancet is used to stick the baby's heel on one side. Blood is collected from adults by venipuncture. The blood is collected by a nurse or phlebotomist from a vein located in the crease of the arm. Serum, the liquid portion of the blood after it clots, is used for the test.

When a person is infected with a pathogen, the normal immune response results in the production of immunoglobulin M (IgM) antibodies followed by immunoglobulin G (IgG) antibodies. IgM antibodies against TORCH organisms usually persist for about three months, while IgG antibodies remain detectable for a lifetime, providing immunity and preventing or reducing the severity of reinfection. Thus, if IgM antibodies are present in a pregnant woman, a current or recent infection with the organism has occurred. If IgM antibodies are absent and IgG antibodies are present and do not demonstrate an increase on serial testing several weeks later, it can be assumed that the person has had a previous infection by the corresponding organism, or has been vaccinated to prevent an infection. If the serum of a person has no evidence of either IgM or IgG antibodies specific for the organism, then the person is at risk of infection if exposed because they do not have any demonstrable immunity.

TORCH testing is most often performed by enzyme linked immunsorbent assay (ELISA). These are double antibody sandwich enzyme immunoassays in which the antigens or organisms are bound to a solid phase such as the bottom of a plastic well. Dilutions of the patient's serum are prepared and incubated with the antigens. Any specific antibodies to the antigen will bind forming antibody-antigen complexes. The wells are washed to remove unbound serum proteins, and enzyme-conjugated antihuman immunoglobulin is added. The wells are washed again to remove any unbound reagent antibody and a substrate is added. If antibodies to the organism are present, the enzyme converts the substrate to a colored product that can be measured. Assays for IgM or IgG antibodies are available. Alternative procedures include latex agglutination, indirect immunofluorescence assay for toxoplasma antibodies, chemiluminescence immunoassay, DNA amplification, and viral culture.

The TORCH panel is used to determine the immune status of a pregnant female for Toxoplasma gondii, rubella, cytomegalovirus, and herpes simplex virus. If IgG antibodies are present at a concentration that indicates immunity against each of these organisms, the female is in no danger of contracting a toxoplasma or rubella infection during pregnancy and transmitting it to the fetus. In addition, there is a low probability of transmitting a herpes simplex or CMV infection, although the antibodies detected by the test may not be fully protective. If antibodies are absent, the patient will be observed closely during the pregnancy for any sign of suspected infection. Should an infection occur, it will need to be treated aggressively to prevent transmission to the fetus.

The organisms which comprise the TORCH panel are commonly encountered. Most people are exposed the them during childhood. In most healthy persons exposed to Toxoplasma gondii, the organism causes an asymptomatic infection or mild self-limiting illness resembling infectious mononucleosis. The same pattern occurs for CMV infection. Rubella causes an acute infection with fever and rash, but is self-limiting with symptoms subsiding in two to three days. Children and young adults are typically infected. Herpes simplex 1 typically causes fever blisters. The infections caused by TORCH organisms are grouped together because they may all result in stillbirth or serious birth defects when transmitted from an infected mother to her fetus during pregnancy.

The symptoms of the TORCH infections in neonates include:

  • small size for gestational age (SGA)
  • enlarged liver and spleen
  • low level of platelets in the blood
  • skin rash
  • central nervous system involvement, including encephalitis, calcium deposits in the brain tissue, and seizures
  • jaundice

This group of defects is called the TORCH syndrome. As such, other organisms causing serious congenital infections such as syphilis, human immunodeficiency virus, parvovirus, and enterovirus are sometimes considered part of this group. A newborn baby with these symptoms will be given a TORCH test and may be tested for some of these other infections as well.

In addition to these symptoms, each of the TORCH infections has its own characteristic symptoms in newborns.

Toxoplasmosis

Toxoplasmosis is caused by Toxoplasma gondii, a parasite that can acquired from ingesting cysts from the feces of infected cats, drinking unpasteurized milk, or eating contaminated meat containing the cyst or trophozoites. The infection is transmitted to the infant through the placenta, and can cause eye deformity, eye infections and mental retardation by invading brain tissue. The later in pregnancy the mother is infected, the higher the probability that the fetus will be affected. On the other hand, toxoplasmosis exposure early in pregnancy is more likely to cause a miscarriage or serious birth defects. The incidence of toxoplasmosis in newborns is between one to eight per 1,000 live births in the United States.

Rubella

Prior to the 1970s the incidence of congenital rubella infection was approximately 6.3 per 10,000 births. Ten years following the introduction of the vaccine the rate dropped six-fold to approximately one in 10,000 births. The rate of fetal infection varies depending on when in gestation the exposure occurred. Approximately 85% of neonates who develop birth defects as a result of infection during pregnancy contract the virus during the first eight weeks of gestation. Infants born with rubella may show signs of heart disease, retarded growth, ocular defects, or pneumonia at birth. They may also develop problems later in childhood, including autism, hearing loss, brain involvement, immune system disorders, or thyroid disease.

Cytomegalovirus

Cytomegalovirus belongs to the herpes virus group of infections. It can be transmitted through body secretions, as well as by sexual contact; some newborns acquire CMV through breast milk. Of newborns in the United States infected with CMV, 10% will have measurable symptoms. The mortality rate for these symptomatic newborns is 20-30%. Surviving infants with CMV may suffer from hearing loss (15%) or mental retardation (30%). Newborns that acquire CMV during the birth process or shortly after birth may develop pneumonia, hepatitis, or various blood disorders.

Herpes simplex virus

Herpes virus infections are among the most common viral infections in humans. They are spread by oral, as well as genital, contact. It is estimated that between one in 1,000 and one in 5,000 infants are born with HSV infections. About 80% of these infections are acquired during the birth process itself; the virus enters the infant through its eyes, skin, mouth, and upper respiratory tract. Of infants born with HSV infection, about 20% will have localized infections of the eyes, mouth, or skin. About 50% of infected infants will develop disease spread throughout the body (disseminated) within nine to 11 days after birth. Disseminated herpes infections attack the liver and adrenal glands, as well as other body organs. Without treatment, the mortality rate is 80%. Even with antiviral medication, the mortality rate is still 15-20%, with 40-55% of the survivors having long-term damage to the central nervous system. It is critical for the doctor to diagnose HSV infection in the newborn as soon as possible, for effective treatment.

TORCH testing is most effectively utilized to determine the mother's immune status and monitor those pregnant females who do not demonstrate immunity. TORCH testing of neonates is difficult to evaluate, since maternal IgG from either present or past exposure crosses the placenta and will often produce higher levels in the neonate than in maternal serum. The infant's IgM response may or may not be developed sufficiently at birth to be definitive, and false positive and negative results are known to occur. When neonates are tested, the TORCH screen should include testing for specific IgM antibodies, and should be repeated within two to three weeks to demonstrate a rise in concentration indicative of active infection. Viral cultures or DNA probe tests are required to make a definitive diagnosis of the specific infection. CMV can be cultured from urine and white blood cells; herpes simplex can be cultured from vesicles on the skin or conjunctiva (mucus membranes inside the eyelids); both CMV and rubella may be cultured from cerebrospinal fluid, but culture time for rubella can take several weeks. Cultures are performed by inoculating living cells such as primary monkey kidney.

Preparation

No special preparation, other than sterile technique, is required.

Aftercare

There is no special aftercare specific to the test itself. Discomfort or bruising may occur at the puncture site, or the person may feel dizzy or faint. Pressure to the puncture site until the bleeding stops reduces bruising. Applying warm packs to the puncture site relieves discomfort.

Complications

For the mother, minor temporary discomfort may occur with any blood test, but there are no complications specific to TORCH testing. For the infant, complications associated with the TORCH test are those resulting from the heelstick technique/venipuncture. These risks include scarring, infection, cellulitis (inflammation of cellular tissue), and small lumpy calcium deposits. Results of serological tests (antibody tests) on the neonate may be inconclusive. Follow-up testing may be needed to demonstrate a rise in antibody titre (concentration). Additional diagnostic testing and/or treatment is determined on a case-by-case basis, depending on results.

Results

A normal result is undetectable IgM antibody in the blood of either mother or neonate. The presence of IgM indicates recent or current infection. When specific IgM antibodies to TORCH antigens are found in the neonate, this indicates a very high probability of infection with the respective organism, and should be followed up by subsequent testing to demonstrate either a rise in titre or by viral culture or DNA tests.

For rubella and Toxiplasma gondii, the presence of a significant IgG titer in maternal serum indicates immunity for both mother and fetus. The presence of IgG antibody to CMV and herpes simplex in maternal serum may or may not be fully protective. When neonatal infection is suspected, TORCH testing of the neonate may not be definitive. IgG antibodies in fetal serum may result from either current or prior maternal infection or vaccination. In such cases, an IgM level should be measured in both maternal and neonatal serum, and viral cultures or DNA testing should be performed.

Results for TORCH antibodies may be interpreted as negative, equivocal, or positive. Equivocal results occur when antibody levels fall within an index value below the low positive standard but above the negative standard. Testing by another method is recommended. In addition, serum from the patient should be collected and retested after waiting an additional 10-14 days.

Health care team member roles

The test is typically ordered and interpreted by a physician. Blood samples for the TORCH screen are collected by a nurse or phlebotomist. Pregnant women found to be exposed should receive treatment and a thorough explanation of potential consequences by their obstetrician. Counseling may be helpful. TORCH testing is performed by a clinical laboratory scientist/medical technologist.

KEY TERMS

Antibody— A protein molecule produced by the immune system that is specific to a disease agent, such as CMV. The antibody combines with the antigen on the organism and facilitates its destruction or removal from the host.

Perinatal— Referring to the period of time surrounding an infant's birth, from the last two months of pregnancy to the first 28 days of life. The TORCH panel tests for perinatal infections.

Small-for-gestational-age (SGA)— A term used to describe newborns who are below the 10th percentile in height or weight for their estimated gestational age. The gestational age is based upon the date of the mother's last menstrual period. SGA is one of the symptoms of TORCH syndrome.

Titre (titer)— The concentration of a substance in a given sample of blood or other tissue fluid.

Resources

BOOKS

Cruse, Julius M., and Robert E. Lewis. Illustrated Dictionary of Immunology. New York: CRC Press, 1995.

"Pediatrics and Genetics: Disturbances in Newborns and Infants." In vol. II, edited by Robert Berkow, et al. Rahway, NJ: Merck Research Laboratories, 1992.

"Procedures: Heelstick (Capillary Blood Sampling)." In Neonatology: Management, Procedures, On-Call Problems, Diseases, and Drugs. 4th edition. Edited by Tricia Lacy Gomella, et al. Norwalk, CT: Appleton & Lange, 1999.

OTHER

Pittsburgh.com. Illustrated Health Encyclopedia. 〈http://www.pittsburgh.com/shared/health/adam/ency/article〉.

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