 Brenda Mills, DVM Leptospirosis Leptospirosis is a bacterial disease that usually causes kidney failure but may also cause meningitis or liver failure. Symptoms may include fever, weakness, pain, inappetence, vomiting, and diarrhea. The organisms are shed in the urine of affected animals, including wildlife, and may survive for weeks or even months in water or moist soil. Leptospirosis is commonly considered to be a “wet weather” disease, and direct exposure to carrier animals is not required for infection due to the possibility of the organism being carried in runoff. Vaccines To acquire immunity, the immune system must be exposed to characteristic structures, usually proteins, that serve as a fingerprint for a bacterial or viral organism. These structures are found on the outside of the organism. There are three ways for an immune system to see these structures: Through natural exposure to the organism (infection) Through intentional exposure to key parts of the dead organism (killed vaccine) Through intentional exposure to the living organism after the organism has been rendered harmless (modified live vaccine) While infection typically results in the longest-term immunity to an organism, the disease caused by infection is what we are trying to avoid by inducing immunity. Killed vaccines are much safer than natural infection, however, since the organism is dead and not reproducing in the animal or doing anything else to excite the immune system, an adjuvant (irritant) is required to provoke the immune response. While the organism portion of the vaccine will be removed in the course of developing immunity, the adjuvant usually remains behind and may act to chronically provoke the immune system. Modified live vaccines introduce actual organisms which are unable to cause disease but otherwise behave exactly like an infection, provoking the immune system without the need for adjuvants. These vaccines are completely cleared from the body when their job is done. Leptospirosis vaccines Most of our vaccines are against viruses, which are much smaller and have less complex fingerprints than bacteria. Vaccines against bacterial diseases are difficult to develop, very complex, and result in short-term immunity. The original Leptospirosis vaccines were made by essentially running the actual organism through a blender to rupture and kill it. This produced a vaccine that was safe from the perspective of not being able to cause disease, but which had a tremendous capacity to over-excite the immune system because the vaccine not only exposed the individual to the important structures on the outside of the bacteria, but also to all of the stuff on the inside. This gave Leptospirosis vaccines their reputation for causing “bad reactions.” These vaccines typically last approximately 11 months. What we use: A huge improvement in the safety and efficacy of Leptospirosis vaccines came with the advent of genetic engineering, which allowed the production of purified subunit vaccines. Through the magic of gene splicing, E. coli was used to produce specific proteins which occur on the outside of the bacteria, reducing the number of molecules in the vaccine, making it safer and more effective. This vaccine still requires the use of an adjuvant and provides approximately 11 months of protection. A newer vaccine, which now provides immunity against the four major species of Leptospirosis, is a non-adjuvanted modified live vaccine. A virus has been engineered to infect the patient’s cells with harmless components which make the cells pump out proteins and train the immune system to recognize the fingerprint of Leptospirosis. This vaccine mimics natural infection without causing disease, provoking immunity which has been shown to last at least 15 months without the use of an adjuvant and this is the vaccine we are currently using – Recombitek by Merial.
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 Brenda Mills, DVM
Fast Facts – as related to the UC-Davis School of Veterinary Medicine Class of 1998 in our required Behavior class:
Additional facts:
In the early days of veterinary vaccine development, vaccines were by necessity clumsy and nearly impotent concoctions created by treating the disease agent to render it harmless and adding a compound to irritate the immune system and make it notice an otherwise harmless agent. These vaccines were far safer than natural exposure to the disease but contained a lot of extra material that the immune system really didn’t need to worry about, and resulted in relatively short-term immunity (1 year or less). The availability of veterinary care and the expense of vaccination meant that many animals were un-vaccinated or under-vaccinated, and even well-vaccinated animals might have faulty immunity, so Parvovirus, Distemper, and the like were potentially life-threatening risks for young dogs who had not completed their vaccine series. Enter the modern-day vaccine. The majority of the vaccines administered by veterinary professionals are now genetically engineered, modified-live vaccines that safely mimic an infection – from the immune system’s perspective – and provoke a strong, targeted immune response with the initial injection. Additional doses are administered to make the immune system “remember” the vaccine and put the important information about the diseases into its long-term memory. Even young puppies can now have good protection, and nowadays behavior is a bigger risk to survival than the diseases against which we vaccinate. Early socialization and training is behavior vaccination! When should puppies go to their first puppy class and puppy socials? Two to 14 days after coming home! In a perfect world, every puppy would be enrolled in a class taught using positive motivation, reinforcement and reward before coming home. If the start date falls within the first 48 hours of bringing your puppy home, or if your puppy requires a “quarantine” period because he or she just came out of the shelter, leave your puppy at home and attend class solo so you can start your homework and keep from falling behind! Which puppies can go about the neighborhood on pavement, rock, and bare dirt from the day they come home? Puppies whose mothers are known to have been up to date on their vaccines or vaccine titers, according to their veterinarian, at the time they were bred and who received a vaccine against Distemper, Adenovirus, and Parvovirus from a veterinary professional at least 10 days before they went to their new homes. These puppies should be experiencing the world from the time they come home even if they are only 8 weeks old. Which puppies should be socialized primarily in their new homes for the first 2 weeks after coming home? Puppies whose breeders use vaccines from the feed store for the mothers and/or the puppies, whose mothers have uncertain vaccine histories, who were not vaccinated before leaving the litter, or who have been out of an animal shelter for less than 2 weeks. Which puppies should wait longer than 2 weeks after going home to go out and about in their new world? Only puppies who are sick! |
AuthorsDr. Brenda Mills and staff members Archives
January 2021
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