Introduction:Leptospirosis can cause a variety of problems including red blood cell destruction, kidney disease, and abortions. Because this organism thrives in wet environments, infections usually occur when animals have access to marshy areas, ponds, streams, and stagnant surface water. Leptospirosis also causes widespread abortion outbreaks, resulting in poor conception rates and loss of profit. These abortions usually occur during the second half of gestation. In general, these infections are considered only a small problem in isolated flocks and herds.
Causative Agent: Leptospirosis is caused by spiral-shaped bacteria known as spirochetes. There are many strains of Leptospira, and most sheep and goat cases are caused by Leptospira pomona, L. icterohaemorrhagiae, and L. grippotyphosa.
Clinical Signs: Clinical signs vary depending on factors such as age and health of the animal, environmental conditions, and which strain (serovar) of leptospirosis is involved. Generally, the signs in lambs/kids include fever, not eating (anorexia), difficulty breathing (dyspnea), and exhaustion. The above signs, along with a yellow discoloration to the gums and white of the eye (icterus), blood breakdown products in the urine (hemoglobinuria), and abortions are also common in adult animals.
Disease Transmission: Leptospirosis is carried to a susceptible animal by
contaminated water, rodents, wildlife, and domesticated animals. Infections
occur when the organism contacts the mucosal surfaces (mouth, eyes, nasal
passages, etc.) or an injured area on the skin of a susceptible animal. Once an
animal is infected, it sheds the bacteria in the urine, semen, vaginal
secretions, or in the placenta and fetal tissues. Because of this, care should
be taken when handling any urine, tissue, semen, or discharge from a
Leptospirosis is a very hardy organism and can survive in the environment for long periods of time, providing freezing temperatures do not occur.
Diagnosis: The most common way of knowing whether leptospirosis is the cause of disease is to run a test called serology. This test requires that blood samples be taken on two different occasions, 14-21 days apart, from the suspect animal or from animals of various age groups in the flock or herd. Leptospirosis is difficult to identify in tissue or body fluid samples and difficult to grow in a culture setting. Because of this, leptospirosis is often diagnosed by excluding other diseases that cause widespread problems in a flock or herd. A chilled, aborted fetus can be sent in to a laboratory for necropsy. Kidney, lung, and body fluids can then be examined for leptospirosis. See page D135 for more information on serology.
Treatment: It has been shown that certain antibiotics (oxytetracyclines and penicillin) are successful at treating the disease if given in the early stages of infection. If leptospirosis is diagnosed early in pregnant animals, abortions can be limited by vaccinating the entire flock or herd and administering antibiotics.
Prevention: For most sheep and goat flocks or herds, prevention involves good management practices. Fencing potentially contaminated streams and ponds, controlling rodent populations, and making certain that the animals are separated from pigs or wildlife are some of the methods used to reduce disease transmission. When purchasing replacement animals from an outside source, select animals that come from flocks/herds that have tested negative for leptospirosis. Before being added to the flock/herd, all replacement animals should be isolated for at least 21-30 days.
Vaccination against leptospirosis for goats and sheep is also an option; however, the decision to vaccinate should be based on the actual need in a particular flock or herd. Because leptospirosis is not a universal problem in sheep and goats, many animals would not require routine vaccination.
If it is decided that vaccination is warranted, vaccines should be given every year to all animals over 3 months of age. Lambs and kids less than 3 months of age should be protected if they are consuming colostrum from a vaccinated dam. Breeding animals should be vaccinated about 3 weeks prior to being bred. To be completely protective, most vaccines must be given every 6 months. Vaccinations are not 100 percent effective in all cases, so it is essential to implement good management practices in addition to vaccination.
Public Health Concerns: Leptospirosis is a "zoonotic" disease, meaning that people can become infected. Caution should be used around any animal suspected of having leptospirosis. Contaminated urine is highly infectious for people and susceptible animals, especially when this urine contacts mucous membrane surfaces or abrasions and cuts. Latex gloves should be worn when handling infected animals or their urine. Protective goggles and masks should be worn when hosing contaminated areas.