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G86-797-A
Causes of Vaccination-Immunization
Failures in Livestock
This NebGuide discusses reasons why vaccinations fail to provide immunity against disease, and how to prevent this from happening.
Duane Rice, DVM, Extension Veterinarian
E. Denis Erickson, DVM, Veterinary Microbiologist
Dale Grotelueschen, DVM, Extension Veterinarian
To comprehend the many reasons for vaccine failure, it is important to understand how animals and humans have the ability to resist infectious diseases. It is also important to know what a disease is and how it affects the animal.
According to Stedman's Dictionary , disease is an interruption, cessation or disorder of body functions, systems or organs. Diseases may be obvious even to the untrained eye, or detectable only by sophisticated testing procedures (subclinical disease). Serious irreversible damage may be done even at the subclinical level if therapeutic or preventive measures are not taken early.
These may be categorized in two types:
- Nonliving , such as chemical poisons (toxins), or excessive heat or cold.
- Living , which includes infectious agents (pathogens), viruses, bacteria (which may themselves produce toxins), and large parasites such as lice and worms.
Resistance can also be divided into two types:
- Nonspecific or innate resistance --resistance that is present in the normal animal prior to infection.
- Specific immune resistance --resistance that arises only after repeated exposure to the agent.
Innate Resistance
This type includes natural barriers such as the skin, the washing effect by secretions such as tears, and certain normal responses such as coughing. Each is a part of the individual from birth, but may be significantly affected by hereditary, nutritional, and environmental influences.
Specific "Immune" Resistance
This type usually arises following exposure of the animal (particularly the white blood cells in the animal) to the infectious agent (an antigen). This exposure can come about during an actual (natural) infection, or artificially by inoculation of the animal with the infectious agent, which has been killed or made nonpathogenic. This procedure is called vaccination . In most cases the animal will respond to the vaccine (antigen) by producing immune bodies called antibodies , and will stimulate production of more white blood cells that react specifically with the inciting agent (vaccine). Occasionally an animal does not respond sufficiently to provide protection. Such animals, in spite of vaccination, have failed to become immune--they are not immunized . Many factors can affect the development of immunity in the individual, and contribute to apparent failures in vaccine protection. The remainder of this NebGuide provides some reasons for such failure.
Age
The very young animal has not had time to develop a competent immune system. On the other hand, the very old animal may have various deficiencies in immunological capability.
Young animals that have received colostrum have also received large quantities of antibodies from their dam. High levels of these passively acquired antibodies can interfere with the development of the young animal's own immune response to vaccines for 1 to 2 months or longer.
Biological Variation
Some animals, due to heritable traits, respond less than the normal population does to antigens either through vaccination or natural infection. Even though they have been inoculated with the vaccine, they may not become immunized.
Nutrition Level
Animals deficient in nutrients may respond poorly to vaccines, as well as being below their genetic production potential.
Interference Due to Concurrent Disease
Certain diseases, if present at the time of vaccination, may prevent an adequate immune response to the vaccine.
Immunodeficiency
Protection against infection of newborn animals is best obtained by passive transfer of antibodies from the dam. Some vaccines are given to the dam in anticipation that she will transfer specific preformed antibodies to her young. These are passively acquired antibodies that are effective for only one to two months in the offspring. However, if she does not respond with adequate antibody levels, or if her offspring do not suckle adequately in the first 12 hours of life, there may be a failure to transfer antibodies to her young.
Antibody Interference
When the antibody level within an animal is present due to maternal or other passive immunity, the antigenic properties of vaccine can be neutralized and no immunity develops. As the passive antibody levels wane, the animal may then have no protection because the vaccine used earlier was inhibited by the very antibody that is now depleted.
Stress
Poor nutrition, shipping, crowding, and other stressful events may produce hormonal or chemical imbalances in the animal that suppress the immune system and its response to vaccines.
Wrong Serotype
The immune response is very specific. A vaccine may contain organisms of the same family as those involved in a disease outbreak, but if they are not of the same serotype (type within the family), the results may be disappointing.
Potency and Purity
Vaccines must have adequate antigenic mass to properly stimulate an immune response. Vaccines not made under strict controls may not have this capability. Purity is also an important factor as contamination may render the vaccine worthless by destroying antigenic properties. Other adverse effects may include abscess development at the site of inoculation, or the introduction of an entirely different disease problem.
Outdated Vaccine
Outdated vaccine may not contain the required antigenic properties due to deterioration or other factors. It is not worth taking a chance that it may work. The investment to obtain fresh, quality vaccine far outweighs the possibility of losing just one animal due to poor vaccine.
Vaccine Limitations
All vaccines have limitations. Some vaccines for certain diseases occasionally do not cause production of enough immunity at both the local and systemic levels to give adequate protection against that disease. Alternate routes of administration and/or boosters are sometimes used to help alleviate this problem. We must not expect more than the vaccine manufacturer indicates.
Handling Procedures
It is imperative that vaccines be stored and used exactly as directed by the manufacturer. Exposure to sunlight, chemicals, drugs, and adverse temperatures may destroy the vaccine's effectiveness. Vaccine that requires mixing should always be used promptly. Sources of purchase of vaccine should be evaluated to help determine if proper care was provided before purchase.
Improper Mixing
Mixing vaccines properly is a "must" as the "antigenic mass," or dosage, is calibrated to produce antibody levels that are protective. Modified live virus (MLV) vaccines must be reconstituted properly, using the diluent supplied for that vaccine in the correct quantity. Administer vaccine only from sterile syringes that have been sterilized without the use of chemicals. Never mix other vaccine types together when not specifically recommended by the manufacturer, as chemical incompatibility is possible.
Timing of Vaccinations
The correct timing of vaccine administration is absolutely necessary to expect a reasonable immune response. Time to build protection, time in relation to animal age, and the time when most resistance to the disease is needed are some of the factors you must consider.
Waning of Immune Status
Immune status can wane to the point of susceptibility when exposure to antigenic material is minimal or absent. For this reason, some manufacturers recommend using a booster vaccination to build a higher antibody level. When the manufacturer's directions recommend a booster, it is necessary that it be done at the recommended intervals . Frequently the first dose only sensitizes the immune system; the second dose is necessary to develop a high protective level.
Overwhelming Challenge
This can occur when excessive animal stress combines with entrance of extremely large numbers of virulent disease-causing organisms. This overwhelming infection can overcome even a relatively strong immune protection.
Mechanics of Vaccination
At the time the vaccine is administered, strict attention to details is very important to prevent "misses." Animals can be missed at vaccination time when too many jobs are being done simultaneously. Organization is very important. Escape-proof pens or corrals and other methods to reduce the "missed ones" are also very important.
Route of Administration
Companies that produce vaccine will specifically label the route of administration and which site of inoculation is preferred. Research by the manufacturer has proven which route is best. If injection in the muscle is specified, the vaccine should not be given by any other route. Your veterinarian should be involved to ensure proper vaccine selection and use.
Animal Protection
Precautions should be taken to ensure the physical well-being of the animal. In addition to vaccine recommendations, precautions should be followed so as not to mechanically damage nerves, joints, or other body parts with the needle. This includes paying attention not only to the area of the animal injected, but also such things as length and gauge of the needle.
All commercially manufactured vaccines are formulated and labelled to be used only on healthy animals . Vaccinating animals in the face of an outbreak would generally be unadvisable as relatively high numbers of these animals would be sick, under stress, and would not be "healthy" at that time. These conditions contribute to vaccine failure.
The causes of vaccine failure are numerous, but if precautions are taken as described in this NebGuide, the "vaccine failures" that occur can be greatly reduced and disappointing livestock losses can be avoided. The best procedure in using vaccines is to CONSULT YOUR VETERINARIAN AND FOLLOW THE MANUFACTURER'S INSTRUCTIONS.
File G797 under: ANIMAL DISEASES
F-4, General Livestock
Issued May 1986; 12,000 printed.
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture. Elbert C. Dickey, Director of Cooperative Extension, University of Nebraska, Institute of Agriculture and Natural Resources.
University of Nebraska Cooperative Extension educational programs abide with the non-discrimination policies of the University of Nebraska-Lincoln and the United States Department of Agriculture.
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