Leptospirosis is an infectious, contagious, and even fatal disease found in cattle. Dawn Prime speaks to a vet to find out more about the disease, its symptoms and treatment options.
Failure to control leptospirosis can have a negative impact on the health and productivity of the herd, and also those working with the herd as it can be passed from humans to cattle.
However, Colin Greer, a vet from Abbey Veterinary Group, Paisley, says that the strategic use of vaccines and controlled management measures to reduce the environmental risks can help keep the bacteria that causes the disease in check.
Mr Greer explains that leptospirosis is a bacterial infection caused by the bacteria from the genus Leptospira.
He says: “Cattle contract leptospirosis by encountering infected urine, abortive material, and reproductive fluid, such as semen, from infected bulls. It can also be contracted by other cattle that are infected with the bacteria, co-grazing with sheep and sharing water courses.”
He adds that clinical symptoms include fever, jaundice, anaemia, blood tinged urine and lack of appetite. Some cattle also drop in milk yield.
Mr Greer also says that bacteria can persist in the cow’s reproductive tract – causing sub-clinical signs, due to chronic infection, which leads to fertility issues and abortions, and usually occur three to twelve weeks following infection.
Most abortions occur during the last three months of pregnancy, but infection of the cow may also produce premature and weak calves.
Mr Greer adds: “Signs of leptospirosis can be non-specific and difficult to diagnose, but include an occasional milk drop, abortion, or the cow that you just could not get into calf. All could be due to leptospirosis."
According to Cattle Health Certification Standards 75 per cent of all cattle are estimated to have been exposed to the leptospirosis causing bacteria.
And the the regulatory body estimates the costs associated are between £68 and £106 per cow in an infected herd.
In terms of cost per litre this works out at a loss of 0.91-1.41ppl.
However, Mr Greer adds that because the symptoms are often ‘vague’ leptospirosis can go unnoticed.
The main method in which leptospirosis can be diagnosed is through bulk milk antibody tests.
Blood antibody tests are a good way to find out if cattle have been exposed to leptospirosis.
However, Mr Greer says a single test will not tell you the whole story.
He says: “A positive test tells you that the cow/herd has been exposed to leptospirosis; it does not tell you if the cow has a problem with leptospirosis.
“Testing for antibodies is a useful tool to establish if there is evidence of infection on-farm without going into the specifics of individual cattle. If you are looking for leptospirosis in certain cows, then test a urine sample or the aborted foetus.
“Paired blood samples, taken three to four weeks apart, can test for individual cows. These samples show if the antibody levels have changed and indicates if the cow has been recently exposed.”
Mr Greer says the treatment is antibiotics, usually streptomycin or dihydrostreptomycin, depending on the stage of infection.
He adds: “Without antibiotics the bacteria will have more time to spread to the herd. An anti-inflammatory can also be useful.”
Mr Greer explains there are vaccines available, which are a a good start in reducing disease on-farm,.
However, he adds: “Remember that the vaccination prevents the disease but does not eliminate in its entirety, so annual boosters are also essential.”
Calves which are born from a vaccinated cow are immune for about six months, after this time they will need their own vaccination program.
Some farmers do not start vaccinating until the bulling heifer stage and infection can occur prior to this. It may be worth considering vaccinating sooner, and for best advice discuss this with your vet.
Bacteria can also be shed from the male reproduction tract in the form of semen and be spread among the other cows. Therefore the use of artificial insemination is often considered safer than using a bull.
Mr Greer says: “Remember, the bull needs regular monitoring to make sure they are bovine viral diarrhoea, infectious bovine rhinotracheitis and leptospirosis free."
Other measures include fencing off cattle from potentially contaminated waters, and the cattle not sharing water with sheep.
As leptospirosis can be passed to humans, usually through exposure to the disease causing bacteria via bodily fluids when the cow is calving or aborting.
However, the most common way of transmission is through infected urine (touching urine or an object that has been urinated on) or contaminated waters.
Mr Greer says: “A cut on the skin is a perfect way for the bacteria to gain entry. It can show in humans as headaches, fever, muscular aches, and sickness.
“Biosecurity is key. Please do not handle dead animals with bare hands and never drink water from rivers.
“Personal prevention is also important, such as washing hands, cleaning, and covering wounds. Protective clothing is also strongly advisable.”