distinguished from other disorders. Recently developed, IgM capture assays provide the clinician with a helpful and reliable test, not affected by rheumatoid factor.
The unreacted conjugate and unbound complex, if any,
move further on the membrane and are subsequently
immobilized by the antirabbit antibodies coated on the
membrane at the control region ‘C’, forming a colored
band. This control band serves to validate the reagent and
FIG. 22.27: Virucheck result reading
1. Flavicheck-HCV membrane test assembly (device)
comprises of HCV specific recombinant antigencolloidal gold conjugate co-dispensed with rabbit
IgG colloidal gold conjugate; predispensed with HCV
with a plastic sample dropper and desiccant.
The test kit should be stored between 4–30°C for the
duration of the shelf-life of the kit as indicated on the
1. In vitro diagnostic test. Not for medicinal use.
2. Do not use beyond expiry date.
3. Read the package insert carefully before performing
4. Handle all specimen as potentially infectious.
5. Follow standard biosafety guidelines for personal
protection, handling and disposal of potentially
Specimen Collection and Preparation
1. No prior preparation of the patient is required before
sample collection by approved techniques.
2. Fresh serum/plasma is preferable. Serum/plasma may
be stored at 2 to 8°C up to 24 hours in case of delay in
testing. For long-term storage, freeze the specimen at
–20°C for 3 months or –70°C for longer periods.
3. Repeated freezing and thawing of the specimen should
4. Do not use hemolyzed, clotted, contaminated,
5. Specimen containing precipitates or particulate matter
must be centrifuged and the clear supernatant only
6. Do not heat inactivate the sample.
Test Procedure and Interpretation of Results
1. Let the sealed pouches attain room temperature
2. Tear open the sealed pouches and retrieve the
appropriate number of test devices as required.
Label the test devices appropriately. Once opened,
the devices must be used immediately. The addition
of sample must be done at the center of the sample
port holding the sample dropper in a vertical
position. Ensure the drops are free falling. Use a new
sample dropper for each specimen to avoid cross
3. Dispense two drops of specimen in to the sample port
(S) using the dropper provided.
4. At the end of 15 minutes, read the results as follows:
Appearance of only one colored band at the control
Appearance of a colored band at the test region ‘T’in
addition to the band at control region ‘C’.
5. The test should be considered invalid if neither the test
nor the control bands appear. Repeat the test with a
6. Based on the concentration of antibodies to HCV in
the specimen a positive result may start appearing as
early as 2 minutes, however, negative results must be
confirmed only at the end of 15 minutes.
7. In case of doubtful results at 15 minutes, the test
may be extended up to a maximum of 30 minutes if
1. Though Flavicheck-HCV is a sensitive and reliable
screening test, it should not be used as a sole criterion
for diagnosis of HCV infection.
2. All positive specimen should be further tested using
appropriate supplemental confirmatory tests. Test
samples that are positive by a third generation
double antigen sandwich-based assays may be
reactive with very early seroconversion samples,
which are negative/intermediate with blot-based
assays. Such samples should be reconfirmed with the
RNA-PCR-based method or must be followed up for
seroconversion at a later date.
3. As with all diagnostic tests, results must be correlated
with clinical findings to arrive at the final diagnosis.
4. Absence of antibodies to HCV does not indicate that
an individual is absolutely free of HCV infection
as the collection of sample and its timing vis-a-vis
seroconversion will influence the test outcome.
5. Do not compare the intensity of test lines and the
control lines to judge the concentration of antibodies
6. Since various tests for HCV differ in their performance
characteristics and antigenic composition, their
reactivity patterns may differ.
7. Testing of pooled samples is not recommended.
TORCH Infections: Introduction
Toxoplasma gondii is an obligate intracellular protozoan
parasite that is probably capable of infecting all species of
mammals, including man. The detection of IgM antibodies
to T. gondii is particularly helpful for the diagnosis of acute/
primary infections in “risk” individuals in association with
AIDS, organ transplantation and pregnancy. As most
of Toxoplasma infections are mild or asymptomatic in
become important for the monitoring of primary infections
in pregnant women, as the parasite can lead to birth
defects. Moreover, as T. gondii infections are most severe
in immunocompromised patients, where the disease can
be fatal, acute infections due to this parasite have to be
distinguished from other disorders. Recently developed,
IgM capture assays provide the clinician with a helpful and
reliable test, not affected by rheumatoid factor.
Infection with Rubella virus in children and adults
is a self-limited, mild disease characterized by an
erythematous rash, mild upper respiratory symptoms
and suboccipital lymphadenopathy. After recovery, the
individual is immune to subsequent infection with rubella
virus. Primary infection of a pregnant woman, however,
particularly in the first trimester of pregnancy, may result
in a high risk of fetal infection with severe complications.
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