Leptospirosis infections in Cattle

What is Leptospirosis?  Leptospirosis, or Lepto as it is commonly called, is an infectious bacterial disease that can affect many species including people. It can be a major problem in cattle. It can either be an acute or chronic infection. Acute infections cause ill thrift and death in calves or decreased milk in lactating or nursing cows. Chronic infections contribute to the most significant losses in a herd causing up to 30% of the herd to abort, have stillbirths, or weak calves. It is present throughout the US.

Etiology:  Leptospirosis is caused by the bacterium Leptospira interrogans and there are multiple serovars. The six most common affecting cattle are Hardjo, Pomona, Icterohaemorrhagiae, Bratislava, Canicola, and Grippotyphos. Of these Pomona and Hardjo are thought to cause the worst clinical disease.

Transmission:  Leptospirosis is most frequently transmitted from urine of infected animals. This urine can contaminate pastures, feeds, water sources or splash in the eyes of susceptible animals. Common animals that may carry leptospirosis are rodents, raccoons, skunks, opossums, foxes, dogs and swine.

Clinical signs for acute infections in calves may include:

¨      Fever

¨      Jaundice

¨      Bloody urine

¨      Loss of appetite

¨      Difficulty breathing

¨      Anemia (loss of blood from hemolysis)

Clinical signs of acute infection in adult cattle may include:

¨      Fever

¨      Bloody urine

¨      Decreased milk production

¨      Milk that is thick and yellow or red

¨      Abortions

Clinical signs in chronic infections of adult cattle may include:

¨      Abortion if cows are in last half of pregnancy

Diagnosing Leptospirosis in the herd:  It is always best to contact your veterinarian if you suspect an outbreak of Leptospirosis in your herd. They can help to determine the likelihood and will know the best samples to collect for a diagnosis. There are generally three ways to diagnose the presence of leptospirosis in your cattle herd. Samples from the placenta and aborted fetuses tissues and fluids can be submitted to a diagnostic laboratory which will use immunofluorescent staining to detect the presence of the organism. Another method would be to try to grow the organism but this is often difficult and unsuccessful. The third and most commonly used method is to take blood samples from a portion of the herd including affected and unaffected animals. The samples will be tested for antibodies against the particular Leptospirosis serovars. It is best to draw two blood samples from the animals at least two weeks apart. The level of antibodies called a titer  will be looked at and your veterinarian can help you understand the reported results. Vaccines also create titers thus making paired samples more useful than single samples.

Treating Leptospirosis:  It is often difficult to treat for the disease in cows because the first sign may be abortions. However if it is caught early enough antibiotics such as tetracycline and streptomycin can be used. It is always best to consult with your veterinarian before using the antibiotics. In the face of a major abortion storm the use of antibiotics and vaccinating the herd can decrease the shedding of the bacterium among the herd and help prevent further abortions. In the acute infection and in young calves, fluids and antibiotics are usually successful if treatment is started soon after initial clinical signs.

Preventing Leptospirosis:  The herd should be vaccinated at least once a year against leptospirosis and ideally twice a year. All replacement animals both heifers and bulls should be vaccinated as well as all other breeding animals. It is best to vaccinate cows 30 days before breeding. Most vaccines are safe for pregnant animals so they can be given during pregnancy diagnoses. It is not recommended to vaccinate calves under 3 months of age as it can lead to residual antibodies. The vaccine is relatively inexpensive and can save you money by preventing even one abortion in the herd.  The cost of an outbreak is obvious, thus all breeding cattle should be vaccinated for Leptosprosis.  Lepto vaccines commonly contain the 5 serovars of Lepto.  There are currently 2 companies with newer vaccines that contain the Hardjo bovis serovar.  Although we have not experienced outbreaks in vaccinated herds, H. bovis can be difficult to diagnose and I often wonder if it is not responsible for some of the late term sporadic abortions that most often go undiagnosed. If you are experiencing some of these undiagnosed abortions then a trial of one of these vaccines to see if it helps may be more economical that diagnostics.

Good management can also decrease the likelihood of transmission of leptospirosis. Some simple steps include:

¨      Eliminating access of cattle to surface water or streams used by other livestock.

¨      Removing trash that harbors wildlife and rats.

¨      Limiting access of rodents and wildlife to livestock feed.

¨      Eliminating urine drainage into water sources.

¨      Reducing contacts between cattle, other livestock, rodents, and wildlife as much as possible.

¨      Cleaning, disinfecting, and drying barns, pens, and other confinement areas after use by infected cattle.

¨      Draining or fencing swampy areas likely to harbor the leptospires.

¨      Vaccinating susceptible animals for relevant serotypes.

*Leptospirosis can infect humans as well and some caution should be taken when handling materials that you suspect may be contaminated, also avoid swimming in suspected contaminated waters.