Veterinary Preventive Medicine-II

CONTROL

• Spread by air borne route is very difficult to control. Control of movement of livestock is one of the effective measures.
• Where the disease is not endemic the policy of quarantine, slaughter and disinfection of infected premises has proved efficient and economical also.
• Slaughter of infected animal stops the production of virus and slaughter of animals in direct or indirect contact with the source of infection breaks the infective chain.
• This is an economic method only in countries where disease incidence is low. In other countries, it may not be economically or socially acceptable and there vaccination is carried out.
• Where the disease is not endemic the policy of quarantine, slaughter and disinfection of infected premises has proved efficient and economical.
• Inactivated vaccines containing serotypes predominant in the geographical areas are available commercially.
• Vaccines may be monovalent, bivalent, trivalent or polyvalent.
• To establish a satisfactory level of immunity it is usual to give a primary course of two inoculations, 2-4 weeks apart, followed by revaccination every 4-12 months.
• In young animals maternal antibody may last for 3-6 months and can interfere with immunization.
• To avoid gap in protection, countries recommend first vaccination at ages ranging from 2-6 months.
• For calves usually first vaccination is given at the age of 4 months, followed by booster at 2-4 weeks interval, revaccination every 6 months or 4-12 months once.
• Sheep and pigs vaccinated at 6 months of age. The dosage of vaccine in sheep is one-third of that of cattle.
• The first vaccination leads to immunity in ruminants for about 3-6 months. Subsequent vaccinations may give protection for a year in cattle but only about 6 months in sheep.
• In the areas where the greatest risk of infection is likely, ruminants are vaccinated three times a year. With a medium risk, animals are vaccinated twice a year.
• In countries where the infection is low ruminants are vaccinated twice the first year and subsequently annually. The choice of strains of FMDV to use in the vaccine is important.