Baa Baa Blood Test? Rare Sheep Could Be Key to Better Diagnostic Tests in Developing World, Says Stanford Study

STANFORD, Calif.--(Business Wire)--
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.

"Up until the time I saw a hair sheep-which I first saw in Botswana-I had no
idea there was even such a thing," said Baron, who is associate director of
Stanford`s clinical microbiology lab, interim director of the clinical virology
lab, and associate chair of pathology for faculty development. She wasted no
time in learning about the animals, finding that they resist parasites, don`t
need to be sheared, and do well in the tropical climes prevalent in much of the
developing world.

But no one had tested whether their blood was equivalent to horse or sheep
blood. So, calling in a favor from a colleague with a hobby farm near Walnut
Creek, Calif., Baron and her colleagues collected blood from hair sheep-the
animals are remarkably mellow about the donations, she said-and created test
cultures using the blood. Then, they ran a series of common diagnostic tests.

"It worked for every single thing," Baron said.

The researchers also found that they could collect the blood in donation bags,
much like those human donors might see at the Red Cross. That`s a big advantage
over the defibrination process the developed world uses. To defibrinate blood,
technicians must shake the samples in a glass jar filled with hundreds of tiny
glass beads constantly during and after the donation. That`s fine in a lab with
machines to do the shaking and autoclaves to sterilize all of those beads, but
it`s an enormous burden in labs without that equipment. Fortunately, Baron
found, hair sheep blood collected in donation bags performed the same as
defibrinated blood.

"It`s very important," said Bruce Hanna, PhD, professor of pathology and
microbiology at the New York University School of Medicine, who was not involved
in the study. "This paper found an alternative that is able to be produced in
Africa and provides identical results to the standardized products that are used
in this country."

Michele Barry, MD, senior associate dean for global health at Stanford medical
school, added: "Diagnosis of bacterial diseases and antibiotic sensitivity in
low resource settings is often infeasible due to cost, access to diagnostics or
manpower. Ellen Jo Baron and colleagues have uniquely decided to combine
veterinary health science and human blood banking to develop a blood agar from
hair sheep as medium to grow bacteria. This sheep is a low-maintenance animal
adopted for hot climates. The technology, which they are modeling in Botswana,
is an example of a practical `can do` innovation in microbiology that will save
lives in the tropics at low cost by quickly identifying bacteria to tailor
cost-effective antibiotic use-a precious commodity overseas."

Now, said Baron and Yeh, the only hurdle is getting the sheep to the labs that
need them. Two veterinary labs in Botswana already provide hair sheep blood to
local labs based on Baron`s initial results. Baron is now lobbying the charity
Heifer International to add hair sheep to its catalogue so microbiologists can
donate and send the animals to the developing world. After all, she said, the
sheep can provide milk and meat-and that`s on top of their role as donors of
blood that, in her words, "works perfectly for every microbiology test that a
laboratory would need to do."

Baron and Yeh`s co-authors on the paper are Stanford pathologist Benjamin A.
Pinsky, MD, PhD, and Niaz Banaei, MD, assistant professor of pathology and
infectious diseases. The study was self-funded by Baron.

NOTE TO MEDIA: A photo of the sheep is available upon request.

The Stanford University School of Medicine consistently ranks among the nation`s
top 10 medical schools, integrating research, medical education, patient care
and community service. For more news about the school, please visit
http://mednews.stanford.edu. The medical school is part of Stanford Medicine,
which includes Stanford Hospital & Clinics and Lucile Packard Children`s
Hospital. For information about all three, please visit
http://stanfordmedicine.org/about/news.html.

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For Stanford University School of Medicine
Print Media:
Jonathan Rabinovitz, 650-724-2459
jrabin@stanford.edu
Broadcast Media:
Margarita Gallardo, 650-723-7897
mjgallardo@stanford.edu

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