Infection characteristics of African swine fever virus genotype II in the field outbreaks

Abstract

The objective of this study was to initially investigate the prevalence of African swine fever virus (ASFV) in the sows in some infected farms considering a number of epidemiological factors, such as: contact characteristics, farm model and disease outbreak time at the farm. The studied result showed that the infection rate of pigs in the opened farm system was higher than in the closed farm system (p<0.05) and in the re-infection farm was higher than in the first infection farm (p<0.05). This rate in the farm with outbreak time >1 week was higher than in the farm with outbreak time <1 week (p<0.001) and in the pigs directly contacted with F0 pigs was higher than in the pigs indirectly
contacted with F0 pigs (p<0.001). The positive rate of blood samples was 35.56% (16/45), while the positive rate of the oral swab samples was 22.22% (10/45). The concentration of ASFV in the blood sample was also higher than that of the swab sample (p<0.01). The results of gene sequence
analysis showed that all the six ASFV collected strains belonged to genotype II and was similar compared to the strains already identified in Viet Nam and in the neighboring countries.