Assessment of immunization procedures for foot-and-mouth disease in large-scale pig farms in China based on actual data and dynamics

Abstract

Foot-and-mouth disease (FMD) is an acute, highly infectious and pathogenic animal disease. In recent years, with the rapid development of the swine breeding industry in China, pig farms have shown a trend of larger-scale development. Large-scale pig farms employ standardized management, a high level of automation, and a strict system. However, these farms have a large trading volume, and increased transmission intensity of FMD is noted inside the farm. At present, the main control measure against FMD is pig vaccination. However, a standard for immunization procedures is not available, and currently adopted immunization procedures have not been effectively and systematically evaluated. Taking a typical large-scale pig farm in China as the research subject and considering the breeding pattern, piggery structure, age structure and immunization procedures, an individual-based state probability model is established to evaluate the effectiveness of the immune procedure. Based on numerical simulation, it is concluded that the optimal immunization program involves primary immunization at 40 days of age and secondary immunization at 80 days of age for commercial pigs. Breeding boars and breeding sows are immunized 4 times a year, and reserve pigs are immunized at 169 and 259 days of age. According to the theoretical analysis, the average control reproduction number of individuals under the optimal immunization procedure in the farm is 0.4927. In the absence of immunization, the average is 1.7498, indicating that the epidemic cannot be controlled without immunization procedures.

Assessing the impact of different contact patterns on disease transmission: Taking COVID-19 as a case

“…If it is less than 1, the infection will decline in the population. According to [18][19][20][21], combined with the definition of the basic reproduction number, we can get that during daytime, the average number of secondary infected individuals caused by an infectious individual with household size-k, age group-a i is:…”

Enhancement of intestinal mucosal immunity and immune response to the foot-and-mouth disease vaccine by oral administration of danggui buxue decoction

“…In today's intensive farming environment, once an individual gets sick, a group infection will soon break out and cause serious economic losses to the breeding industry ( 3 ). Presently, vaccination is the most important means for the prevention and control of FMD ( 4 ). Therefore, compulsory immunization with FMD vaccine was adopted in China to prevent and control the disease, which can control a possible pandemic of FMD to a certain extent ( 5 ).…”