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Sleeping sickness
Molecular tools for diagnosisThe parasitologic tests in use for diagnosis of human African trypanosomiasis (HAT), or sleeping sickness, have low sensitivity, and current serologic tests have inadequate specificity. Detection of trypanosomal DNA sequences from a patient’s blood, urine or saliva could be a significant improvement on parasitological examination. Loop-mediated isothermal amplification (LAMP) of DNA is a promising new molecular technique that shows high sensitivity and specificity, amplifies target DNA under isothermal conditions, meaning that the test can be carried out with minimal equipment. Furthermore, positive samples are identified visually either through the formation of a white precipitate or through a color reaction (see example with SYBR Green in Figure 1). LAMP can also be used for the simultaneous analysis of large numbers of samples, and can be performed by staff with minimal experience in molecular biology. This test may also be useful for confirming cure in treatment follow-up.
FIND has been working with Murdoch and Obihiro Universities, as well as research institutes in endemic countries, to develop and evaluate the potential for HAT diagnostics based on LAMP technology. Sets of primers that are specific to the subgenus Trypanozoon, T.b. rhodesiense and T.b. gambiense are being designed and tests optimized using DNA from various members of the sub-genus Trypanozoon. The most sensitive and specific primer sets will be validated using samples from HAT patients. Reproducibility of the tests in laboratories based in the endemic regions has already been verified. This work has given sufficiently promising results to support adaptation of the LAMP technique for diagnosis of HAT. See papers by Z.K. Njiru, et al:
[pdf 420kb] In 2005, FIND partnered with Eiken Chemical Company Ltd (Japan), the owner of the patent rights to LAMP, to work together in developing and supplying a diagnostic test for Mycobacterium tuberculosis for the developing world. Eiken has already developed and marketed other infectious disease tests, including assays for Salmonella detection, various E. coli detection kits, Listeria monocytogenes and Campylobacter detection kits based on LAMP. FIND has a close and ongoing collaboration with Eiken to assess opportunities to use LAMP for diagnosing other infectious diseases, including HAT. © Foundation for Innovative New Diagnostics 2008. Click here to see the copyright notice |
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