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Leptospirosis
Karalee
Gehl, DVM
Staff Veterinarian
Technical Service
What
is Lepto?
Leptospira is a spirochete in the Leptospiraceae family. A
spirochete is a slender, motile bacteria with a multi-layered
membrane containing flagella on each end which give it the
ability to move spontaneously. It’s an aerobic bacterium,
meaning it needs oxygen to survive and it favors temperatures
between 50 and 90 degrees F.
Who
does it affect?
Leptospirosis is an infectious and contagious bacterial
disease of most farm animals and many wildlife species. In
nature, spirochetes are shed in the urine and survive in many
types of water or damp alkaline soil. In the USA
, disease in farm animals is primarily due to the Leptospira
serovars hardjo, pamona, canicola, icterohaemorrhagiae
and grippotyphosa. However, others have also been
isolated. The manifestations of this disease can vary
greatly depending on the infecting serotype. It’s also
a zoonotic disease, meaning it can be transmitted to people.
What’s
the source and transmission of Lepto?
Leptospira organisms are transmitted by an infected animal’s
urine which comes into contact with an uninfected animal.
As the disease spreads through the unvaccinated herd,
the immunity of the herd increases and the incidence of the
disease decreases. Once
most of the animals are immune, exposure decreases and
therefore immunity will start to wane.
This allows cattle to become infected again, either by
carriers or by some other fresh exposure to infection.
It is believed there is an increase in infections
during the rainy season or flooding. This organism resides in
the kidneys, but can also reside in the liver, lungs and
reproductive tract. It gains entry into the body by way of the
eyes, nose, mouth or broken skin. It can be spread by
infected rodents, raccoons, skunks, foxes or by an infected
member of the herd.
What
are the clinical signs?
Calves can be severely affected with acute Leptospirosis.
Clinical signs can range from a fever, anorexia, difficulty
breathing and jaundice. The urine may have a red color, which
is blood in the urine; this is where the term ‘Redwater of
calves’ comes from. (Redwater is also a term used in
infections caused by Clostridium
haemolyticum.) Morbidity and mortality are higher in
calves than adult cattle.
In adult cattle, the clinical signs can
vary dramatically. They range from abnormal milk, drop in milk
production, jaundice, anemia, submucosal hemorrhages and blood
in the urine. Abortion
storms also can occur in herds that have recently been
introduced to Leptospira.
Pigs are infected primarily by rodents.
Abortions that occur 2 to 4 weeks before term, are the most
common manifestation of Leptospira in pigs. Piglets that are
born with Leptospira may be weak or die soon after birth.
How
is it diagnosed?
Serology with paired serum samples, direct culture in special
media, or fluorescent antibody techniques on tissues are
methods used to confirm clinical and postmortem findings. The
most commonly used technique is the microscopic agglutination
test (MAT). When
evaluating or diagnosing a herd, sera should be obtained from
various age groups.
How
can it be prevented or controlled?
Annual vaccinations and confinement rearing are used for
control. Annual vaccination should be used in closed herds,
where semiannual vaccination should be considered for open
herds. Calves and piglets can be vaccinated at 4-6months of
age.
When vaccinating for the first time with
Colorado Serum Company’s Lepto-5
bacterin, a booster is recommended 2-4 wks later, then annual
vaccinations. Vaccinate cows 30 days prior to breeding.
Colorado Serum’s Lepto-5
protects against the five most common forms of Leptospirosis
found in the
United States
- Leptospirosis canicola,
grippotyphosa, hardjo, icterohaemorrhagiae, and pamona.
Bacterins may provide protection against
abortions, death and reduce renal infections, although some
infections do occur. It is important to reduce transmission by
controlling rodents, fencing cattle from potentially
contaminated streams and ponds, separating cattle from pigs
and wildlife, and selecting replacement stock from herds that
are seronegative for Leptospirosis.
References:
1.http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51202.htm&word=leptospirosis%2cin%2ccattle
2.http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/51205.htm&word=leptospirosis%2cin%2cpigs
3.http://www.iowabeefcenter.org/pdfs/bch/03230.pdf
4.http://www.aces.edu/pubs/docs/A/ANR-0858/ANR-0858.pdf
5. http://www.agric.nsw.gov.au/reader/cattlehealth/leprospirosis-cattle-herds.htm
6. Proceedings of the 6th Western Dairy Management
Conference. March 12-14, 2003. Reno, NV-157. Carole A.
Bolin, DVM, PhD. Department of Pathobiology and Diagnostic
Investigation College of Veterinary Medicine, Michigan State
University, East Lancing, MI 48824.
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