Monday, November 23, 2009

Strange sheep and their blood

Sometimes the right person spots the right sheep at the right time. It was several years ago in Botswana that Ellen Jo Baron, Ph.D., first laid eyes on the sheep that she now thinks will revolutionize the diagnosis of infectious disease in poor countries.

Baron, an internationally recognized Stanford pathologist, has spent years training lab technicians in the developing world to diagnose infectious diseases. In fact, she literally wrote the book on microbial diagnosis. But she realized it was time to adapt when she discovered one of her densely-worded textbooks locked away and covered in dust in a Malaysian hospital office. She created a low-text, flowchart-rich version of the book for non-English-speaking settings.

Having simplified her textbook, she then had to confront the fact that the photos in it didn't correspond to what her trainees were seeing under their microscopes. The book featured pictures of organisms grown on standard Western lab plates, which are based on sheep- or horse-blood agar. Those animals require too much expensive care and handling to make them available to low-resource labs, which must use human blood instead. Apart from being a biohazard, human blood doesn't behave the same way that animal blood does in diagnostic tests--so the labs that use it couldn't make sense of the photos in her textbook.

Then came her trip to Botswana, where she saw one of these. "'What is that?'" she recalls asking herself. "Clearly, it wasn't a goat and it wasn't a sheep--it was some other thing." It was a hair sheep, a cousin of the familiar wool sheep that has some unsheeplike traits. It is happy in hot climates and small pastures, resistant to parasites and other infections, and, of course, needs no shearing. Such a low-maintenance animal, Baron realized, could be a big boon to labs in the developing world. After finding a rare herd of wool sheep at an experimental farm in California and convincing the owners to let her tap the sheeps' jugulars, Baron tried the standard microbial diagnostic tests on hair sheep blood, at her own expense. All the tests worked beautifully. The blood produces standard results without the need for expensive techniques or unaffordable animals.

Clinical laboratories are unsung and unglamorous places, but they are in many ways the brains of the hospital--or at least the left hemisphere to the physician's right. Microscopes and centrifuges and other analytic equipment allow for the types of decision-making--about patients' health, about germs and their drug susceptibilities, about genes even--that revolutionized 20th-century medicine. Yet few American doctors visit their hospital's lab or know the name of its director. Few of us have looked down a microscope or counted colonies since those squirmy afternoon sessions in medical school, and that leaves us both unprepared to diagnose malaria or anemia singlehandedly and unappreciative of the equipment and supplies and expertise that are needed to make that diagnosis. In short, we seldom think about how central the laboratory is to any medical effort. Photogenic medical missions to fix cleft lips and congenital heart defects are sorely needed, but so are the bent backs of the microscopists--perhaps more so.

Hearing of Baron's discovery, people have begun to come out of the woodwork, wanting to help. An American hair sheep breeders' association is interested in sending sheep to Southeast Asia and training people in their simple husbandry. A Brazilian blood distribution company has offered a citrated blood-storage bag. And one Botswanan lab is beginning to use hair sheep already. All Baron needs is the time and money to put the hair sheep where they're needed. She's determined to do it. As she told a Stanford interviewer last fall, getting hair sheep to labs in the developing world "is going to change everything."

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