New biomolecular assays must be tested by direct study in the developing world

EDITOR—Garner et al's editorial on appropriate diagnostics in developing countries is welcome to those who develop novel diagnostic systems for tuberculosis, which remains the most important infectious disease globally.1 Conventional diagnosis is difficult, and most developments have centred on molecular amplification techniques, often using the polymerase chain reaction, which are expensive and less sensitive than culture. 2 3 Ethical issues arise if precious samples such as cerebrospinal fluid are repeatedly subdivided for research.

Per capita healthcare spending in the developed world …