The Filariasis IgG/IgM Rapid Test is a lateral flow immunoassay for
the simultaneous detection and differentiation of IgG and IgM
anti‐lymphatic filarial parasites (W. Bancrofti and B. Malayi) in
human serum, plasma or whole blood. This test is intended to be
used as a screening test and as an aid in the diagnosis of
infection with lymphatic filarial parasites. Any reactive specimen
with the Filariasis IgG/IgM Rapid Test must be confirmed with
alternative testing method(s).
SUMMARY AND EXPLANATION OF THE TEST
The lymphatic filariasis known a s Elephantiasis, mainly caused by
W. bancrofti and B. malayi, affects about 120 million people over
80 countries 1,2. The disease is transmitted to humans by the bites
of infected mosquitoes within which the microflariae sucked from a
n infected human subject develops into third‐stage larvae.
Generally, repeated and prolonged expo sure to infected larvae is
required for establishment of human infection. The definitive
parasitologic diagnosis is the demonstration of microflariae in
blood samples3. However, this gold standard test is restricted by
the requirement for nocturnal blood collection and lack of adequate
sensitivity. Detection of circulating antigens is commercially
available. Its usefulness is limited for W. bancrofti4. In
addition, microfilaremia and antigenemia develop from months to
years after exposure. Antibody detection provides an early means to
detect filarial parasite infection. Presence of IgM to the parasite
antigens suggest current infection, whereas, IgG corresponds to
late stage of infection or past infection5. Furthermore,
identification of conserved antigens allows ‘pan‐filaria’ test to
be applicable. Utilization of recombinant proteins eliminates
cross‐reaction with individuals having other parasitic diseases6.
The Filariasis IgG/IgM Rapid Test uses conserved recombinant
antigens to simultaneously detect IgG and IgM to the W. bancrofti
and B. malayi parasites without the restriction on specimen
The Filariasis IgG/IgM Rapid Test is a lateral flow chromatographic
immunoassay. The test cassette consists of: 1) a burgundy colored
conjugate pad containing recombinant W. bancrofti and B. malayi
common antigens conjugated with colloid gold (Filariasis
conjugates) and rabbit IgG‐gold conjugates, 2) a nitrocellulose
membrane strip containing two test bands (T1 and T2 bands) and a
control band (C band). The T1 band is pre‐coated with monoclonal
anti‐human IgM for the detection of IgM anti W. bancrofti and B.
malayi, T2 band is pre‐coated with reagents for the detection of
IgG antiW. bancrofti and B. malayi, and the C band is pre‐coated
with goat anti rabbit IgG. When an adequate volume of test specimen
is dispensed into the sample well of the cassette, the specimen
migrates by capillary action across the cassette. W. bancrofti or
B. malayi IgM antibodies if present in the specimen will bind to
the Filariasis conjugates. The immunocomplex is then captured on
the membrane by the pre‐coated anti‐human IgM antibody, forming a
burgundy colored T2 band, indicating a W. bancrofti or B. malayi
IgM positive test result. W. bancrofti or B. malayi IgG antibodies
if present in the specimen will bind to the Filariasis conjugates.
The immunocomplex is then captured by the pre‐coated reagents on
the membrane, forming a burgundy colored T1 band, indicating a W.
bancrofti or B. malayi IgG positive test result. Absence of any
test bands (T1 and T2) suggests a negative result.
Contact Rebecca Yan