Rare sheep could be key to better diagnostic tests in developing world, says Stan...( STANFORD Calif. The newest revolutio...),Health

STANFORD, Calif. The newest revolution in microbiology testing walks on four legs and says "baa."

It's the hair sheep, a less-hirsute version of the familiar woolly barnyard resident. A new study from the Stanford University School of Medicine, which is to be published July 3 in PLoS ONE, finds that not only are these ruminants low-maintenance and parasite-resistant, they're also perfect blood donors for the microbiology tests necessary to diagnose infectious disease in the developing world.

Identifying microbes from a patient's urine or sputum requires growing those microbes in culture dishes filled with gelatinous agar and a small amount of blood. The blood provides nutrients to the growing bugs and also provides clues as to the microbes' identities: Microbiologists can rule out or identify certain strains of bacteria based on how the organisms interact with the blood cells in culture.

In the developed world, microbiologists use sheep or horse blood. But in many parts of the developing world, horses are prohibitively expensive, and regular sheep, with their constant need for shearing and tendency to get infections, are difficult to keep alive. Importing animal blood isn't feasible either, as shipping is costly and often unreliable.

Many labs in the developing world use human blood, often donated by lab technicians themselves. But diagnostic tests aren't standardized for human blood, said Ellen Yeh, MD, a resident in pathology at Stanford and first author on the paper. "You don't get the same test results when you use human blood versus sheep blood," she said. In addition, the use of human donors increases technicians' risk of infection with blood-borne diseases.

Ellen Jo Baron, PhD, professor of pathology at the medical school and senior author on the paper, wanted to do better. She's a veteran of overseas microbiology, having trained lab technicians from Botswana to Cambodia for more than a decade.