Easy, Inexpensive Test Detects Tuberculosis
in Livestock and Wildlife By
November 21, 2002
A test developed by Agricultural Research Service scientists
for detecting bovine tuberculosis may not only be revolutionary, but very
timely as well.
The breakthrough--a new blood-based assay for detecting the
disease in animals--is important because it is applicable for most if not all
species of mammals and requires only a single blood sample. That means animals
are handled just once.
A patent application for the test has been submitted by the
U.S. Department of Agriculture on behalf of
the inventors, veterinarians Ray Waters and Mitch Palmer. They work in the
of Livestock Research Unit at ARS' National Animal Disease Center in
Ames, Iowa. ARS is the USDA's chief scientific research agency.
The assay detects nitrite--as an indication of nitric oxide
production--in blood-sample cultures. Mammals produce nitric oxide as a natural
response when fighting tuberculosis.
According to Waters, the test is an inexpensive and easy process
for diagnostic laboratories and regulatory agencies. It will likely be used on
livestock species such as cattle, sheep and goats and on wildlife such as deer,
bison and elk.
Currently, the only government-approved tuberculosis-detection
method is a skin test that causes a reaction that is measured 72 hours later.
Handling the animal a second time can lead to injury and stress, especially to
wildlife species, according to Waters.
Eradication efforts started by the USDA in 1917 almost
eliminated bovine tuberculosis. But recent developments, including outbreaks
among white-tailed deer in Michigan and feeder cattle in Texas, show that the
disease is still active in the United States.
The new, still-unnamed test can detect all three types of
tuberculosis--human, avian, and bovine--according to Palmer. He notes that
another test, an interferon gamma assay already in use for livestock, is based
upon the same blood-culture principle as their procedure. However, it can't be
used on other species and can only be applied in conjunction with the skin
Read more about this new test in the
November issue of
Agricultural Research magazine.