Diagnostic accuracy of a duplex real-time reverse transcription quantitative PCR assay for detection of African horse sickness virus.

The research paper analyzes the effectiveness of a diagnostic test, called a “duplex real-time reverse transcription quantitative PCR assay,” in detecting African horse sickness virus (AHSV). The study found that this assay demonstrated a high degree of accuracy in the detection of the virus.

Sample Collection and Testing

• Blood samples were collected from 503 suspected cases of African horse sickness, 503 uninfected and unvaccinated horses from South Africa, as well as 98 samples from horses in a country free from this disease.
• These samples were then tested using two methods: a duplex real-time reverse transcription quantitative PCR assay (AHSV RT-qPCR) and virus isolation (VI).

Estimation of Diagnostic Sensitivity and Specificity

• The study estimates the diagnostic sensitivity and specificity of the AHSV RT-qPCR assay and VI through a 2-test 2-population Bayesian latent class model.
• This method makes no assumptions about the true infection status of the animals tested. It also allows for the possibility of correlation in test results, a conditional dependence.

Findings of the Study

• The median diagnostic sensitivity of the AHSV RT-qPCR was 97.8%, while its specificity was 99.9%.
• The virus isolation method demonstrated a median diagnostic specificity of >99%, but its sensitivity was significantly lower at 44.2%.
• These results show that the AHSV RT-qPCR assay is both analytically and diagnostically sensitive and specific.
• Additionally, this method allows for rapid, high-throughput analysis of samples.

Conclusion and Potential Use

• The study concludes that the AHSV RT-qPCR assay is useful in demonstrating whether horses are free from or infected with the African horse sickness virus.
• It suggests further validation of this assay in other laboratories worldwide to establish it as a global standard for detecting AHSV.