Lifestyle Options Dwindle for Bovine
Bacteria By Ann
Perry August 7, 2007
The bacterium that causes leptospirosis, one of the most widespread
infections transmitted between animals and humans, appears to be changing in
ways that could limit its ability to survive and thrive.
Research suggests that Leptospira borgpetersenii serovar
Hardjo, which commonly infects cattle, is losing its capacity to live in water
and is evolving towards a strict host-to-host transmission cycle. This finding
is from Agricultural Research Service (ARS) microbiologist
L. Zuerner, who works at the agency's
Animal Disease Center in Ames, Iowa, and scientists at
Monash University in Australia.
People and animals can be infected with Leptospira when exposed
to water contaminated with urine from infected animals, or by direct contact
with bodily fluids or tissue from infected animals. Pregnant cows infected with
serovar Hardjo may experience abortion or stillbirth, or give birth to weakened
offspring. Infected humans can develop flulike symptoms orin more severe
Worldwide, most cases of bovine leptospirosis are due to infection by
L. borgpetersenii, but both L. borgpetersenii and L.
interrogans transmit leptospirosis among cattle in North America. Many
Leptospira strains, including L. interrogans, can be transmitted
through surface water.
Genomic sequencing studies conducted by Zuerner and his Australian
colleagues Ben Adler and Dieter Bulach indicate that the L.
borgpetersenii genome is decaying, which is impairing its ability to sense
environmental changes, acquire nutrients and survive outside of a mammalian
host. These changes have also significantly reduced or eliminated the ability
of L. borgpetersenii to survive in water, which in turn restricts its
effectiveness at spreading disease. It appears that L. borgpetersenii is
now contracted mainly, if not solely, through close contact with infected
This research provides a foundation for comparing the
disease-transmission processes of L. borgpetersenii and L.
interrogans, and for developing increasingly effective vaccines and other
disease control strategies for bovine leptospirosis.
more about this research in the August 2007 issue of Agricultural
ARS is the U.S. Department of
Agriculture's chief scientific research agency.