Wednesday, December 21, 2016
Leptospirosis in cattle.
Leptospirosis is one of the most common causes of abortion in cows and also causes infertility and milk drop in cows.The economic value of a farm where leptospirosis infection is present is reduced due to death of calves, and drop in milk . Leptospirosis is a zoonosis causing disease in humans, farmers / farm-workers, abattoir workers and vets are the main risk groups. The disease in man is usually acquired from contact with the urine, afterbirth or aborted fetus of an infected animal or with contaminated water. The signs of the disease in humans are flu-like, with headaches and fever which progresses to meningitis. The cattle shed leptospires in high levels in urine, milk and fetal fluids and this shedding persists for a number of weeks. Recovered animals may intermittently shed leptospires in urine as many animals become renal carriers of the bacteria after infection. At the onset of leptospiral infection,the bacteria localizes in the kidney and urinary tract,this is followed by sudden drop in milk yield which is usually followed by abortions 6-12 weeks after infection. The abortion rate in a herd is about 30% while a herd with previous history of infection is about 5%, this actually shows the importance of the infection as calving expectation is reduced not only that, where leptospires are shed in milk this becomes a waste as it cannot be sold because of public health concerns. The overall picture is that the cost of rearing the animals during that season brings no profit,hence a calving cycle/cow in the herd is lost. Infertility is another sign of leptospirosis,where conception rates are extremely low in the herd necessitating culling of unproductive cows,while cows that are infected during pregnancy have weak calves that die shortly after birth. Bio security measures must instituted on farms and followed strictly as the bacteria can survive in stagnant water,wet soil and streams for 6 weeks.Keep shed dry and clean and use of foot dips and car dips are also important. Handle any aborted calf carefully,wash hands and disinfect after coming in contact with abortion fluid or tissue.