Challenges and Future Directions in African Swine Fever Diagnosis

Accurate diagnosis is fundamental to the successful control of African swine fever (ASF). Over the years, significant advances have been made in molecular diagnostics, serological assays, and rapid point-of-care technologies, providing veterinarians with a broader range of diagnostic options than ever before. However, selecting the right diagnostic approach is not always straightforward. Factors such as the stage of infection, sample type, circulating virus strains, and the intended purpose of testing can all influence diagnostic outcomes. 

For practicing veterinarians, understanding these practical challenges is essential for interpreting results correctly and choosing the most appropriate diagnostic strategy for surveillance, outbreak investigations, and disease control. 

Diagnostic Challenges in Everyday Practice 

No single diagnostic method is suitable for every field situation. Conventional laboratory-based techniques offer excellent analytical sensitivity and are capable of processing large numbers of samples. However, these methods require specialized equipment, laboratory infrastructure, and trained personnel, which may not always be available during field investigations or emergency situations. 

Rapid diagnostic platforms have addressed many of these operational challenges by enabling testing closer to the point of need. Although these technologies improve accessibility and reduce turnaround time, they should be selected based on the diagnostic objective and field conditions, as different platforms offer different analytical capabilities. 

Another evolving challenge is the increasing diversity of ASFV strains. The emergence of gene-deleted and recombinant viruses has created a need for diagnostic assays capable of distinguishing these variants while maintaining reliable detection performance^1,2,3,4. 

Sample Selection Can Influence Diagnostic Success 

Choosing the right sample is just as important as selecting the appropriate diagnostic test. 

Although blood remains the most commonly used specimen for ASF diagnosis, additional sample types are proving valuable for surveillance and disease investigation. These include: 

• Oral fluids, which provide a practical and less invasive sampling option for surveillance⁵. 

• Ear tissues, which can be useful for virus detection under field conditions⁶. 

• Inguinal lymph nodes from dead pigs, which provide another valuable specimen for diagnostic testing⁷. 

Expanding the range of suitable clinical samples gives veterinarians greater flexibility when collecting specimens under different farm and outbreak conditions. 

Future Diagnostic Priorities 

Future developments in ASF diagnosis are expected to focus on improving both diagnostic performance and field applicability. 

One important area is the integration of pathogen detection and antibody detection. Antibodies against proteins such as p72, p54, p30, pK205R, and pB602L appear at different stages of infection, making antibody testing an important complement to molecular diagnosis⁸. 

This integrated approach becomes particularly valuable with attenuated ASFV strains, where intermittent viremia may reduce the likelihood of detecting infected animals using pathogen detection alone⁹. 

Additional priorities highlighted for future diagnostic development include: 

• Improving the sensitivity of rapid point-of-care diagnostic methods. 

• Developing assays capable of detecting latent infection carriers. 

• Enhancing diagnostic tools for import, export, and transportation quarantine. 

• Expanding diagnostic capabilities to address the continued emergence of new ASFV variants. 

Key Takeaway 

African swine fever diagnostics continue to evolve in response to changing disease patterns and field requirements. Future diagnostic strategies are expected to combine improved point-of-care technologies with broader sampling options and integrated pathogen and antibody detection. By understanding the strengths and limitations of available diagnostic methods and selecting the most appropriate approach for each clinical situation, veterinarians can strengthen surveillance, support timely disease investigations, and contribute to more effective ASF control programmes. 

References 

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2. Yang H, Peng Z, Song W, Zhang C, Fan J, Chen H, Hua L, Pei J, Tang X, Chen H, Wu B. A triplex real-time PCR method to detect African swine fever virus gene-deleted and wild type strains. Frontiers in Veterinary Science. 2022 Sep 15;9:943099. https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.943099/pdf 

3. Velazquez-Salinas L, Ramirez-Medina E, Rai A, Pruitt S, Vuono EA, Espinoza N, Gladue DP, Borca MV. Development real-time PCR assays to genetically differentiate vaccinated pigs from infected pigs with the Eurasian strain of African swine fever virus. Frontiers in veterinary science. 2021 Oct 27;8:768869. https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2021.768869/pdf 

4. Guo Z, Li K, Qiao S, Chen XX, Deng R, Zhang G. Development and evaluation of duplex TaqMan real-time PCR assay for detection and differentiation of wide-type and MGF505-2R gene-deleted African swine fever viruses. BMC veterinary research. 2020 Nov 9;16(1):428. https://link.springer.com/content/pdf/10.1186/s12917-020-02639-2.pdf 

5. Prickett JR, Zimmerman JJ. The development of oral fluid-based diagnostics and applications in veterinary medicine. Animal Health Research Reviews. 2010 Dec;11(2):207-16. https://doi.org/10.1017/S1466252310000010

6. Goonewardene KB, Onyilagha C, Goolia M, Le VP, Blome S, Ambagala A. Superficial inguinal lymph nodes for screening dead pigs for African swine fever. Viruses. 2022 Jan 4;14(1):83. https://www.mdpi.com/1999-4915/14/1/83 

7. Lee HS, Bui VN, Dao DT, Bui NA, Le TD, Kieu MA, Nguyen QH, Tran LH, Roh JH, So KM, Hur TY. Pathogenicity of an African swine fever virus strain isolated in Vietnam and alternative diagnostic specimens for early detection of viral infection. Porcine health management. 2021 May 2;7(1):36. https://link.springer.com/content/pdf/10.1186/s40813-021-00215-0.pdf 

8. Hu Z, Tian X, Lai R, Wang X, Li X. Current detection methods of African swine fever virus. Frontiers in Veterinary Science. 2023 Dec 8;10:1289676. https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2023.1289676/full 

9. Kosowska A, Cadenas-Fernández E, Barroso S, Sánchez-Vizcaíno JM, Barasona JA. Distinct African swine fever virus shedding in wild boar infected with virulent and attenuated isolates. Vaccines. 2020 Dec 16;8(4):767. https://www.mdpi.com/2076-393X/8/4/767