Torch Test Toxoplasmosis Rubella Cytomegalovirus Herpes Simplex Virus in details
Posted By HealthcareOnTime Team
Posted on 2021-07-30
TORCH SCREEN Test - Protecting the Naive
"I cried with joy when I saw two pink lines on the strip. I was very happy but at the same time the thought
of Pregnancy did scare me a little. The excitement to welcome my little angel into this world transcended
all my worries but then, I lost my baby!" said a weeping woman who visited a clinic to consult for her
pregnancy loss, Doctor suggested a thorough medical workup. thyroid, liver, LDL-bad cholesterol, blood sugar tests and karyotyping were normal. However, she tested positive for TORCH.
What is TORCH?
Andres Nahmias in 1971, coined the term "TORCH," categorizing a group of perinatal infections found to
manifest similar clinical symptoms. TORCH infections initially comprised of Toxoplasmosis, Rubella,
Cytomegalovirus and Herpes Simplex Virus. As more infectious agents causing similar symptoms became
recognized, the 'O' in TORCH is now denoted as "Other infections". TORCH infections acquired during
pregnancy are one of the leading causes of prenatal and infant morbidity and mortality i.e. may lead to
permanent fetal damage and even fetal loss.
Toxoplasmosis infection is caused by an obligate intracellular parasite Toxoplasma gondii.
This causative agent is a protozoan with a wide host range including humans and warm-blooded
animals (especially cat family). Humans may get infected by consuming under cooked and
contaminated meat pork, lamb, and venison) or shellfish, raw eggs, etc. Infections also occur
from exposure to infected cat feces, litters and contaminated water or soil. Infected mothers
may pass on the infection to the developing fetus through placenta (congenital toxoplasmosis).
Higher risk of transmission has been found to be in later stage of pregnancy (third trimester).
If mother gets infected in early stages of pregnancy first and second trimester), it may result
in a more severe outcome such as miscarriage or birth defects in newborn. More recently it
has also been discovered that T.gondii can be sexually transmitted. Incidence of Toxoplasmosis
of 1 in 1,000 live births have been reported in newboms in India.
Rubella is a contagious viral infection that manifests in peculiar red rashes. Also known as German
measles, it is caused by infection with Rubella virus (family Togoviridae) which has a single-stranded
RNA genome. Rubella infection is spread by airborne transmission i.e. through inhalation of contaminated
aerosol particles. Measles Rubella (MR) Vaccination given as a part of immunization programme in India
has brought down the infection rate. However, infected pregnant women can pass on the virus to the
developing fetus. Infection in the early stage of pregnancy may manifest a severe outcome at birth known
as Congenital Rubella Syndrome (CRS). A higher incidence of congenital rubella infection
(0.6% among asymptomatic infants and 12% among infants) has been reported in India.
CMV belongs to the virus family herpesviridae and has a double-stranded DNA genome. It is a common virus
whose transmission is mediated through contact with infected body fluids such as saliva or urine. CMV can
also be sexually transmitted. Infected mother can transmit CMV to newborn transplacentally or through
breast milk. Majority of people and newborns with CMV infection may remain asymptomatic as CMV may
remain latent. A higher risk to fetus has been reported if the mother acquires infection during initial stage
of pregnancy (first trimester) which include hearing loss or epilepsy. About 1.8-2.1% incidence of congenital
CMV has been reported in India.
Herpes Simplex Virus (HSV)
HSV belongs to the virus family herpesviridae and has a double-stranded DNA genome. There are two
forms - HSV1 (oral herpes) and HSV2 (genital herpes). Pregnant women may also acquire HSV infection
via sexual contact with an infected person and subsequently pass the infection to the developing fetus
during delivery. HSV1 infection may be acquired through direct skin-toskin contact with infected lesions
after rupture of membranes leyes, skin or mouth contact). Neonates mostly acquire HSV2 infection while
they pass through an infected birth canal during delivery. Incidence of HSV infection is between
1 in 1,000 and 1 in 5,000 live births.
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Syphilis Syphilis is a sexually transmitted disease caused by the spirochete Treponema pallidum. Pregnant
women may also acquire Syphilis infection via sexual contact with an infected person and subsequently pass
the infection transplacentally to the developing fetus. This infection can also spread through direct contact
with a spirochete containing lesion. Risk of transmission (congenital syphilis) has been found to increase as
the pregnancy progresses. If mother gets infected in early stages of pregnancy (first and second trimester), it
may result in a more severe outcome.
Parvovirus B19 belongs to the virus family Parvoviridae and has a single-stranded DNA genome. Parvovirus
infection is also known as Fifth Disease and has peculiar presentation in the form of facial red rashes in
children. The virus is transmitted through contact with contaminated respiratory tract secretions or
contaminated blood. Pregnant women with parvovirus infection can transmit it to the fetus.
Human Immunodeficiency Virus (HIV)
HIV belongs to the virus family Retroviridae. There are two types of HIV: HIV-1 and HIV-2. Both of them affect
human beings. HIV genome consists of two single stranded RNA molecules. HIV can be transmitted due to
sexual contact with infected person. Moreover, exposure to infected blood or use of contaminated needles
or sharp objects may also transmit HIV. Transplacental transmission of HIV can happen to the fetus from
infected pregnant mother with the highest risk of infection during delivery due to exposure to the maternal blood.
Varicella-Zoster Virus (VZV)
VZV belongs to the virus family herpesviridae. It is highly infectious and known to cause Chicken Pox and Herpes
Zoster (Shingles). VZV is transmitted via airbome contact with infected aerosols or respiratory secretions.
VZV can be transmitted transplacentally from infected mother to developing fetus.
Common clinical manifestations associated with TORCH infections during pregnancy and in newborns are:
- Severe Complications - Miscarriage, stillbirth, premature birth or Intrauterine Growth Restriction (IUGR)
- Hepatosplenomegaly (enlargement of liver and spleen)
- Skin Lesions - Petechiae and purpura (skin hemorrhage), maculopapular rash, blueberry muffin rash
(in rubella), subcutaneous edema
- Ocular Diseases - Chorioretinitis (inflammation of choroid and retina), cataract (clouding on eye lens),
Microphthalmia (small eyeballs) and other retinal and comeal abnormalities
- Microcephaly (small head size)
- Central Nervous System Complications -
Encephalitis (inflammation of brain), intracranial calcification (calcium deposits in the brain tissue)
- Hearing Impairment -including deafness
- Cardiac Deficits - Pulmonary artery stenosis, patentductus arteriosus, myocarditis
- Mental Retardation
What is TORCH Screen test?
TORCH screen test is a panel of specific serological tests which measures the presence of antibodies
against TORCH infections. TORCH screen panel includes measuring the IgM and IgG antibody titers of
infections Toxoplasmosis, CMV, Rubella and HSV type 1 and 2 by Enzyme Linked Immunosorbent Assay
(ELISA) technique. Serum sample is required for TORCH screen.
When we acquire any infection, our body's immune system produces different antibodies
(immunoglobulins, Ig) to fight the foreign infectious agents. IgM antibodies are first produced
to fight a new infection and is a measure of an acute infection. IgG antibodies produced later are
the most abundant type of antibodies which remain in our body life long and is a measure of a
past infection. Maternal IgG antibodies undergo selective transfer across placenta and confer
protection to fetus against infections in future.
TORCH screen will thus help in identifying pregnant women who have acquired these infections
and thus at a high risk to pass along these infections to developing fetus.
IgM (positive). Current or present infection
IgM (negative) and IgG (positive) - Previous infection/ vaccination taken
IgM (negative) and IgG (negative) - No infection
Other Methods To Diagnose Torch Infections
Real Time. Polymerase Chain Reaction (RT-PCR) -
It is a sensitive test which detects and quantitatively measures the presence of individual infections principle
of amplifying specific region of the genome of pathogen required to determine genotype. Detection of
nfectious DNA OG RNA in amniotic fluid or chorionic villi can confirm fetal infection. It is used for
diagnosis of Toxoplasmosis, Rubella, CMV, HSV, Syphilis, Parvovirus B19, VZV and HIV.
Culture (blood/urine/lesion/CSF) - Culturing of sample to detect specific pathogen and also
checking the cytopathic effects on cells
Dark field microscopy and VDRL/RPR tests -For detection of Syphilis
Are only pregnant women at risk?
No. TORCH infections can affect anybody. Men, women (non-pregnant) and children may also
catch these infections.
Then why so much emphasis on pregnant women?
Pregnant women with TORCH infections pass on these infections to the fetus either transplacentally
or during the birth process through contact with blood or other body fluids.
I am pregnant but I have no symptoms. Should I also opt for TORCH screen?
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Sometimes TORCH infections may not result in any visible clinical symptoms in the expecting mother,
but the developing fetus may be at a major risk. All pregnant women may undergo TORCH screen.
Presently Available Treatment Modalities
- Toxoplasmosis: A combination of sulfadiazine and pyrimethamine drugs is used
to treat toxoplasmosis.Spiramycin drug is also used which has shown to prevent the
trans-placental transmission of Toxoplasma.
- Rubella: Specific treatment is not available, but supportive care is beneficial
- CMV: Antiviral drugs ganciclovir and valganciclovir have shown promising results
to control the infection
- HSV and VZV: Acyclovir is the drug of choice
- Syphilis: Penicillin is the drug of choice
- HIV: Antiretroviral therapy is used
- Parvovirus B19: Specific treatment is not available,but intravenous immunoglobulins may be beneficial
Best method of preventing the TORCH infection is maintaining proper personal hygiene.
Proper immunization can be provided to fetus in form of vaccination (Rubella vaccine).
Routine TORCH screening in women planning for pregnancy can be a preventive measure.
Consuming under-cooked meat should be avoided. Only clean drinking water (boiled or filtered)
or properly washed fruits and vegetables should be consumed.
Thyrocare offers two TORCH
- TORCH All Eight and TORCH All Ten. TORCH All Eight
includes measuring Toxoplasma IgM and Toxoplasma IgG levels, CMV, Rubella and HSV by ELISA.
TORCH All Ten includes measuring IgM and IgG levels of Toxoplasma, CMV, Rubella,
HSV1 and HSV2 by ELISA.