The amount of CD4 cells in the blood indicates both how well a patient's immune system is doing as well as how far AIDS has advanced. When the count drops below a set amount, the patient can then be given antiviral drugs; yet, because current technology is expensive to operate and maintain, the tests are too expensive for most Africans. University News Service has the story on how J. Paul Robinson, a professor in the Weldon School of Biomedical Engineering and the School of Veterinary Medicine, is working with Parker Hannifin and other partners to provide low-cost, easy-to-maintain systems that can make the tests affordable.