Assessment of African Swine Fever Diagnostic Techniques as a Response to the Epidemic Outbreaks in Eastern European Union Countries: How To Improve Surveillance and Control Programs

Abstract

This study represents a complete comparative analysis of the most widely used ASF diagnostic techniques in the EU using field and experimental samples from animals infected with genotype II-ASFV isolates circulating in Europe. To detect the ASFV, three different PCRs were evaluated in parallel using 785 field and experimental samples. The results showed almost perfect agreement between the UPL-PCR and the real-time (κ= 0.94_{[95% CI, 0.91-0.97]}) and conventional (κ= 0.88, _{[CI95% = 0.83-0.92)}) OIE-prescribed PCRs. The UPL-PCR had greater diagnostic sensitivity for detecting survivors and allows earlier detection of the disease. When compared to the commercial antigen ELISA, good-to-moderate agreement (κ= 0.67 _{[95% CI, 0.58-0.76]}) was obtained with a sensitivity of 77.2% in the commercial test. For ASF-antibody detection five serological methods were tested including three commercial ELISA tests, the OIE-ELISA and the confirmatory immunoperoxidase test (IPT). Greater sensitivity was obtained with the IPT than with the ELISAs since the IPT was able to detect ASF antibodies at an earlier point in the serological response, when few antibodies are present. The analysis of the exudate tissues from dead wild boar showed that IPT could be a useful serological tool for determining whether or not animals had been exposed to virus infection — regardless of whether antibodies were present or not. In conclusion, the UPL-PCR in combination with the IPT was the most trustworthy method for detecting ASF during the epidemic outbreaks affecting EU countries in 2014. The use of the most appropriate diagnostic tools is critical when implementing effective control programs.