What is the most effective way to prevent and control foot-and-mouth disease? All the methods are here
Preventing foot-and-mouth disease this way is the most effective!!!
I. Introduction to foot-and-mouth
1.0 Epidemic prevention
1.1 Survival time of the virus in the environment
The virus survives 14 days in dry feces, 6 months in mud, and 39 days in urine. In soil it can survive 3 days in summer and 28 days in winter.
1.2 Transmission
2.2.1 Transmission through personnel: people in contact with infected animals can retain and exhale the virus for up to 36 hours and become a source of infection.
1.2.2 Airborne transmission
Aerosols from infected animals spread through the air. Pigs excrete the largest amount of airborne virus, releasing 400,000,000 virus particles per day. Cattle are the most susceptible to airborne transmission; 0 to 12 virus particles can infect one cow. Birds can also play a role in transmission.
1.3 Immunity to foot-and-mouth disease
Foot-and-mouth disease has 7 serotypes, and these 7 serotypes are mutually independent diseases. At present, porcine foot-and-mouth disease is mainly type O, type A and Asia1. Among them, type O foot-and-mouth disease is the most common infection and the most difficult to prevent and control, and should be given attention. It should be reminded that the type O foot-and-mouth disease vaccine has no cross-protection against type A foot-and-mouth disease. At present, the type A foot-and-mouth disease vaccine is only available for cattle, not for pigs. However, cattle foot-and-mouth disease vaccine cannot be used to inject pigs, while pig foot-and-mouth disease vaccine can be used to inject cattle. Because pig foot-and-mouth disease vaccine requires a higher antigen content, generally speaking, the vaccine dose for 1 pig can be used to inject 10 cattle, while the amount of foot-and-mouth disease vaccine used for 10 cattle can only be used to inject 1 pig.
Immunization is one of the comprehensive measures for foot-and-mouth disease prevention and control. Immunization can reduce the susceptibility of animals; effective immunization can reduce the transmission of the virus between animals: it can reduce the amount of virus shed; then if foot-and-mouth disease occurs, can emergency vaccination control the epidemic? Tests show that the effect of emergency vaccination in dairy cows is relatively good, followed by sheep, and the effect of emergency vaccination in pigs is the worst. It cannot eliminate foot-and-mouth disease, but it can reduce the amount of virus transmission.
Whether an outbreak of foot-and-mouth disease in a pig herd can be controlled through immunization remains doubtful. Immunization cannot prevent transmission, but it can delay an outbreak. When herd immune protection reaches 85%, it can provide herd protection and ensure that foot-and-mouth disease will not cause a pandemic.
Foot-and-mouth disease immunization can reduce the number of cases and gradually reduce the virus in the environment, but it will not eradicate the disease.
In addition, vaccines cannot guarantee that animals will not contract foot-and-mouth disease, so daily biosecurity measures are very important. Some largebreeding pigfarms in the south do not allow vehicles transporting pigs and feed to enter within a radius of one kilometer outside the farm.
1.3.1 Factors affecting the immune effect of foot-and-mouth disease vaccine
Factors affecting the immune effect of foot-and-mouth disease vaccine mainly include the following: the efficacy of the vaccine itself (some vaccines do not have enough antigen content); vaccine storage conditions; the method of vaccine use (multivalent vaccines are superior to monovalent vaccines); the matching between vaccine strains and epidemic strains; maternal antibodies; immune tolerance, immunosuppressive diseases, especially PRRS (if PRRS occurs on a pig farm, it is more susceptible to foot-and-mouth disease).
1.3.2 Differences between bovine foot-and-mouth disease and porcine foot-and-mouth disease
1.3.2.1 Different speed of immune response: cattle produce an immune response relatively quickly, while pigs are relatively slow;
1.3.2.2 Different immune effects: the immune effect in cattle is better;
1.3.2.3 Different amounts of antigen required for immunization: more for pigs and less for cattle. The Netherlands immunized pigs in the 1960s and 1970s, and the pig vaccine contained 4 to 10 times the antigen of cattle vaccine. Therefore, pig foot-and-mouth disease vaccine can be used to immunize cattle, but using cattle foot-and-mouth disease vaccine to immunize pigs will not achieve the immune protection effect.
1.3.2.4 Differences in infection routes: cattle are infected through the respiratory tract.
1.3.2.5 Differences in the amount of virus shed: more for pigs and less for cattle.
2. The most common questions about PRRS vaccine
2.1 Application strategies of gene-deleted PRRS vaccine
2.1.1 Forbreeding pigsthat are unstable and growing pigs that are unstable, vaccinate the whole herd, with two vaccinations at an interval of 4 weeks for the first immunization, and do not vaccinate piglets at this time.
2.1.2 Forbreeding pigsthat are unstable and growing pigs that are stable
Vaccinate the whole herd, with two vaccinations at an interval of 4 weeks for the first immunization; at this time piglets can be vaccinated at 2 to 4 weeks.
2.1.3 Forbreeding pigsthat are stable and growing pigs that are unstable
Vaccinate sows after each farrowing, and vaccinate piglets at 2 to 4 weeks.
2.1.4 Forbreeding pigsthat are stable and growing pigs that are stable, vaccination may be omitted, or sows may be vaccinated after each farrowing and piglets vaccinated at 2 to 4 weeks. Considering the possible presence of classical swine fever infection, piglets can be vaccinated with PRRS vaccine and classical swine fever vaccine at the same time at 4 weeks of age.
2.2 Precautions for vaccine use
1.2.1 A pig farm and a pig herd should use only one attenuated vaccine to prevent mutual interference and avoid the risk of recombination.
2.2.2 Use vaccines with low virulence and few side effects to prevent adverse effects on the pig herd and prevent immunosuppressive effects on the pig body.
2.2.3 Use vaccines with good homology; for variant strains, vaccines against the variant strains should be used.
2.2.4 Use vaccines with a short duration of virus carriage in the body, to prevent virulence reversion from too long a carriage period and prevent virus shedding and transmission to non-immunized pigs.
2.2.5 Use vaccines with heat-resistant protective agents to ensure the stability of the vaccine dose.
II. How to effectively prevent and control foot-and-mouth disease?
Clarify the overall goal: the foot-and-mouth disease virus has six fears: it fears high temperature, sunlight, acid, alkali, formalin, and vaccines.
Ensure that the environment inside the pig house is dry and the room temperature is controlled between 15-22 degrees, and set up an insulated box for piglets in the farrowing house (temperature controlled at 25-28 degrees).
2. Once foot-and-mouth disease is found in surrounding areas, emergency vaccination should be carried out immediately for the pigs on the farm, and at the same time caustic soda and quicklime should be used to disinfect the pens; potassium permanganate or iodine solution should be sprayed into the pig house space to disinfect the air, etc.
3. Improve the body resistance of the pig herd and do a good job in pig farm health care. It is recommended to enhance the nonspecific immune capacity of the pig herd, especially the ability to resist viral diseases.
4. Do a good job in foot-and-mouth disease vaccination on the pig farm: breeding sows are vaccinated once every 4-6 months, and finishing pig herds are vaccinated 2 times, with the first vaccination at 23-25 days of age and the second at 60 days of age. However, the immune stress of foot-and-mouth disease vaccine is particularly severe, and its clinical manifestations are: allergic collapse, rapid breathing, cyanosis of the skin, increased body temperature, decreased feed intake, and even death in severe cases. Therefore, mostpig farmsare unwilling to vaccinate, which brings huge difficulties to foot-and-mouth disease prevention and control. In response to vaccine stress, alleviate the immune stress and allergic reactions of foot-and-mouth disease vaccine, produce high levels of foot-and-mouth disease antibodies, increase daily weight gain, reduce the feed-to-meat ratio, prevent the occurrence of foot-and-mouth disease, and improve breeding efficiency.
III. What should be done if foot-and-mouth disease has already occurred on a pig farm? ⟦61 General principle of handling: when foot-and-mouth disease or suspected foot-and-mouth disease occurs on a pig farm, effective emergency measures must be taken according to the principle of “early, fast, strict, and few” to eliminate foot-and-mouth disease in the bud as soon as possible.
General principles for handling: When foot-and-mouth disease or suspected foot-and-mouth disease occurs on a pig farm, the principles of "early, fast, strict, and limited" must be followed, and effective emergency measures must be taken to eliminate foot-and-mouth disease in its early stages as quickly as possible.
Early: once discovered, isolate immediately, and carry out emergency vaccination for the other pig herds.
Fast: immediately lock down the affected farm, and prohibit the sale of any pigs to the outside during the outbreak period. The keepers of this production line stay at their posts and must not work in other pig houses (cross-warehouse), and immediately use disinfectants with good efficacy against the virus to strictly disinfect the pig houses, pig herds, and main passages in the production area.
Strict: culling sick pigs is a key measure to control the spread of foot-and-mouth disease, and dead pigs are deeply buried.
Few: according to the condition of the sick pigs, a small amount oftreatmentmay be given, such as: if there are symptoms of myocarditis, a small amount of cardiotonic drugs can be used. Apply gentian violet to the ruptured hoof areas. (Source: Internet)