Simplified cytometry for routine monitoring of infectious diseases

The interacting epidemics of HIV/AIDS, tuberculosis (TB) and malaria in resource-poor areas of the world have created a critical need for rapid, simple, affordable apparatus and tests that will permit patients with these diseases to be promptly diagnosed and properly managed. As documented in the current issue of Clinical Cytometry, complex flow cytometric analyses used in affluent countries for CD4+ T cell counting in HIV/AIDS have been simplified, introduced, and quality assessed in resource-restricted countries of Africa and the Caribbean, where simple gating protocols such as panleucogating now provide accurate and precise CD4+ T cell counts on a large scale. CD4/CD8 ratios in infants may replace more expensive molecular tests for HIV infection; simplified flow cytometry is also compatible with HIV viral load-associated lymphocyte activation tests and with antigen-specific cellular immune response assays that rapidly diagnose active TB in both HIV-negative and HIV-TB co-infected individuals. In addition, it is becoming evident that smaller, much less expensive fluorescence imaging cytometers can be used for CD4 counting, immunophenotyping, and hematology and for other applications such as diagnosis and drug-susceptibility testing of TB and diagnosis of malaria. With the gradual, organized expansion of the much-needed diagnostic networks in the underprivileged countries, the most cost-effective apparatus may be one capable of performing tests for all the three diseases mentioned. The most sustainable systems will be those that can be assembled and maintained, to the greatest extent possible, in the countries where they will be used.