Towards practical diagnostics. It remains technically challenging to develop accurate and affordable diagnostics suitable for use in the developing world.
Accurate diagnosis of infectious disease is important both for treatment of individual patients but also, more generally, for monitoring the prevalence and spread of disease. Unfortunately, clinical symptoms alone are rarely sufficient to allow unambiguous identification of a causative organism, while culture-based or other methods of identification usually require referral to central facilities – which is slow, inefficient and expensive. We have a long-standing interest in diagnostics, for diseases such as African trypanosomiasis (sleeping sickness), tuberculosis and malaria.
To be of practical value, diagnostics must be both highly sensitive (detecting an infectious agent whenever it is present) and specific (not generating ‘false positives’ – positive results when an organism is not actually present). These can be highly challenging criteria to fulfill. Furthermore, for use in the developing world, an additional set of criteria are important, such as ease of use, reliability, affordability, robustness and the practicalities of use in resource-poor settings.
In the past we have explored the potential of proteomics-based approaches – analysis of characteristic peptide fragments – for trypanosomiasis and TB. Recently, DNA-based methods combined with nanotechnology sensors have emerged as a highly promising approach, as in our Nanomal consortium (see right). With Professor Phil Butcher at St George’s, we are also working with Nanomal’s technology partners, QuantuMDx, to develop an affordable DNA-based diagnostic for TB.
We have also used our diagnostics expertise closer to home. Our evaluation of diagnostic tests for the important microbial pathogen Clostridium difficile, for example, revealed significant issues in the way the results of commercially available diagnostic tools were being interpreted, and recommended a screening
approach overcoming these drawbacks.
Papadopoulos MC et al. A novel and accurate diagnostic test for human African trypanosomiasis.Lancet. 2004;363(9418):135863.
Agranoff D et al. Identification of diagnostic markers for tuberculosis by proteomic fingerprinting of serum.Lancet. 2006;368(9540):1012–21.
Planche T et al. Diagnosis of Clostridium difficile infection by toxin detection kits: a systematic review.Lancet Infect Dis. 2008;8(12):777–84.