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Pig Loss Analysis of Virulent ASFV Infections Under Different Test and Removal Success Scenarios

African swine fever (ASF) is known as an infectious disease-causing high mortality of pigs and is notifiable to the World Organization of Animal Health (OIE). The etiological agent in the African swine fever virus (ASFV) has an incubation period varying from 4 to 19 days. Dr. Jiancong Yao at PIC analyses the virulent ASFV infections under different test and removal success scenarios.

Extract:

‘Pig Loss Analysis of Virulent ASFV Infections Under Different Test and Removal Success Scenarios’

While ASFV has been challenging the Chinese veterinarians and pig producers, the industry has tested and pioneered the strategy of test and removal to contain the disease. Though the success rates have varied, the test and removal strategy which highly hinged on early detection and people capabilities for biosecure and rapid removal, has helped many farms avoid being fully depopulated.

In this study, by distilling the experience gained from Chinese veterinary practitioners, the author intends to decipher the loss of ASFV under different health management scenarios and readers can infer its economic impacts in farm situations, by comparing with benchmark production parameters.

Test and Removal Strategy

“Test and removal” is to detect the ASFV infected pigs and remove them biosecurely from the herds to avoid further spreading diseases to other herds and pigs. This strategy uses the biology characteristic of ASFV which primarily transmits via direct contact of pig to pig, or via indirect contacts of contaminated fomites, thus transmits slowly. Early detection of the infected pigs needs three factors to be in place: 1) right samples from at risks pigs; 2) reliable diagnostic tools, such as fluorescent quantitative PCR and 3) a trustable veterinary diagnostic laboratory (VDL) and proficient staff who performs the testing. Very often, false positives can be generated by a VDL, and sometimes, a truly infected animal is missed.

The strategy has been widely utilised by pig veterinarians in China, but the publications are rare. Dr. Jiancong Yao have authored two papers on this subject and two success cases were all involved full depopulation of one barn in the setting of the big production compound.

Typical Baseline Breeder Herd Production Parameters Without Economically Important Diseases

Without major economically important diseases infections, in a typical well performing breeder farm with 1,000 production sows, we expect to give birth to 24,000 live pigs, and average mortality in a year in this herd is expected to be 15.62%. The cross-sectional average mortality rate (include one turn in each stage) is expected to be 6.07%.

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