Hot on the Tail of Poultry Killer
By Jill Lee
February 25, 1999
Not all forms of Salmonella make people sick. Some kindsnot
harmful to humansstrike poultry flocks and damage farm profits. For
years, scientists have misunderstood one poultry-killing strain of
Salmonella. Now a U.S. Department of
Agriculture researcher has found a way to track this bacteria more
effectivelyand in the process has overturned 60 years of
accepted research about the microbe.
For years, scientists said Salmonella pullorum lacked the ability to
propel itself through blood and other fluids because it lacked whip-like tail
fibers known as flagella. A special growth medium helped a scientist with
USDAs Agricultural Research
Service discover that the microbe did, indeed, have flagella.
Most strains of salmonella have thick, strong flagella. But pullorum
has fine, feather-like flagella. A new growth medium made the pullorum
grow flagella to detectable levels. Adapted staining procedures also made them
more visible. The discovery was confirmed with an electron microscope.
Knowing pullorum possesses these propelling tails will lead to better
detection methods. When a chickens body recognizes foreign invaders like
pullorum, it starts making antibodies--special proteins that fight the
infection. Flagella cause the body to react by releasing more and different
kinds of antibodies, making detection easier. Early detection means an outbreak
is more easily contained.
Pullorum devastated the U.S. poultry industry shortly after the turn
of the century. USDA has been part of a successful national control effort
since the 1930s, although serious and expensive outbreaks still occur
sporadically in the U.S. In developing countries, pullorum disease
remains a widespread problem and exacts a heavy economic toll on the poultry
industry. The disease is passed from hens to eggs. It kills chicks in the first
weeks of life.
ARS is the USDAs chief scientific agency.
Scientific contact: Peter
Poultry Research Laboratory, Athens, Ga., phone (706) 546-3442, fax (706)