Intended Use:

Tell Me Fast One Step Visceral Leishmaniasis (VL) Test is a rapid immunochromatographic assay for the qualitative detection of antibodies to members of L. donovani in human serum, plasma or whole blood. The test provides a visual, qualitative result, and all positive specimens must be confirmed with other qualified assays. The test is intended for healthcare professional use only.

Summary and Principle:

Leishmania is a genus of Trypanosomatid protozoa, and is the parasite responsible for the disease leishmaniasis. It is spread through sandflies of the genus Phlebotomus in the Old World, and of the genus Lutzomyia in the New World. Their primary hosts are vertebrates; Leishmania commonly infects hyraxes, canids, rodents, and humans. Leishmania currently affects 12 million people in 88 countries. Visceral leishmaniasis infections are often recognised by fever, swelling of the liver and spleen, and anemia. They are known by many local names, of which the most common is probably Kala azar, which is Caused exclusively by species of the L. donovani complex (L. donovani, L. infantum syn. L. chagasi). Found in tropical and subtropical areas of all continents except Australia, visceral infections are most common in Bangladesh, Brazil, India, Nepal and Sudan. Visceral leishmaniasis also found in part of China, such as Sichuan Province, Gansu Province and Xinjiang Uygur Autonomous Region. Most forms of the disease are transmissible only from animals (zoonosis), but some can be spread between humans. Human infection is caused by about 21 of 30 species that infect mammals. These include the L. donovani complex with three species (L. donovani, L. infantum, and L. chagasi); the L. mexicana complex with four main species (L. mexicana, L. amazonensis, and L. venezuelensis); L. tropica; L. major; L. aethiopica; and the subgenus Viannia with four main species (L. (V.) braziliensis, L. (V.) guyanensis, L. (V.) panamensis, and L. (V.) peruviana). Cutaneous leishmaniasis is the most common form of leishmaniasis. Visceral leishmaniasis (Kala azar) is a severe form in which the parasites have migrated to the vital organs and can be fatal if untreated.   Visceral leishmaniasis - also known as kala azar - is characterized by irregular bouts of fever, substantial weight loss, swelling of the spleen and liver, and anaemia (occasionally serious). If left untreated, the fatality rate in developing countries can be as high as 100% within 2 years. As per WHO 90% of Visceral leishmaniasis cases occur in Bangladesh, India, Nepal, Sudan & Brazil. VL is a severe disease with high mortality. It is caused by members of the Leishmania donovani complex and canines have been identified as the major reservoir for transmission.  Serodiagnosis has been widely utilized to establish infection because antileishmanial antibody titers are high during acute disease.  The preferred method of diagnosis in a laboratory situation is by ELISA, although fluorescent antibody (IFAT) or direct agglutination tests (DAT), both utilizing whole parasites, are still widely used.  These tests are highly cross-reactive with trypanosomes and mycobacteria.  In addition, the whole parasite preparations used are unstable and variable in quality.  This rapid assay is for the qualitative determination of antibodies to a recombinant antigen specific for Visceral Leishmaniasis caused by parasite members of the L. donovani complex.   Biocan Tell Me Fast Test utilizes a recombinant antigen, rK39, which has been shown to be specific for antibodies in patients with VL caused by members of the L. donovani complex. rK39 is a fusion polyprotein comprising regions of L. donovani haspb1 (L. infantum k26 homologue), L. donovani kinesin (L. infantum k39 homologue) and L. donovani haspb2 (L. infantum k9 homologue). This antigen, which is conserved in the kinesin region, is highly sensitive and predictive of the onset of acute disease. The antigen is derived from L. chagasi, which in the United States is used for veterinary purposes, though it is not approved for human use. High antibody titers in immunocompetent patients with VL have been demonstrated. This antigen has been reported to be 100% sensitive and 100% specific in the diagnosis of VL and PKDL by ELISA. Another important facet of anti-rK39 antibody is that the titer correlates directly with the disease activity, indicating its potential for use in predicting response to chemotherapy. It was previously shown that anti-rK39 antibody titers were 59-fold higher than those of antibody against CSA at the time of diagnosis, and with successful therapy, it fell sharply at the end of treatment and fell further during follow-up monitoring. RK-39 can capture circulating antibodies against all three component proteins (Haspb1, LdK39, and Haspb2) leading to a more robust signal. Therefore, it is likely that tests using rK39 protein could potentially diagnose individuals that are missed by rK28. The development of an rK39-based point-of-care test has yielded promising results and will become a valuable tool in rapid diagnosis of VL in conjunction with complementary tools such as parasite circulating antigen detection tests and nucleic acid detection tests and permit addressing the under-reporting of this neglected disease.   Tell Me Fast One Step Visceral Leishmaniasis (VL) Test is a qualitative, membrane based immunoassay for the detection of antibodies to Visceral Leishmaniasis in human serum.  The test antigen is immobilized on a nitrocellulose membrane within the test zone. The liquid conjugate is applied to the device through the reagent port, priming the device to facilitate the migration of serum applied in the sample port. The specific antibodies present in the serum are captured by the immobilized antigens and subsequently visualized in the form of a magenta-colored test line by the conjugate. Regardless of the presence of antibody to VL antigen, as the mixture continues to migrate across the membrane to the immobilized control line region, a red line at the control line region will always appear.  The presence of this red line serves as verification for sufficient sample volume and proper flow and as a control for the reagents.