Evaluated blood test in points of attention for disease of the Ebola virus

Evaluated blood test in points of attention for disease of the Ebola virus

By the editorial team of Labmedica in Spanish

The current diagnosis of the disease of the Ebola virus (EVD) is based on the technology of polymerase chain reaction with reverse transcription (RT-PCR), which requires laboratory personnel qualified and technical infrastructure.

The lack of capacity on the diagnostic laboratory has led to diagnostic delays of the current outbreak of EVD in West Africa in 2014 and 2015, endangering the control of the outbreak, with an estimated 24,701 cases and more than 10,000 deaths.

The scientists from King’scollege of London (United Kingdom) and their international colleagues evaluated the diagnostic accuracy of a rapid diagnostic test (RDT) for the EVD, in comparison with the gold standard for the Ebola virus (EBOV), RT-PCR in an operational environment for the diagnosis of suspected cases of Ebola admitted to the units of retention (EHUs) in the western area of Sierra Leone. A total of 138 participants were enrolled and were recruited consecutively at the study sites, from January 22 until February 16 2015.

The Science Lab and Defense Technologies (DSTL, Porton Down, United Kingdom) has developed a rapid diagnostic test for antigen (VDR) for the diagnosis of the EVD. The DSTL EVD VDR is a lateral flow test bedside that uses capillary blood instead of venous blood to detect the presence of an antigen not revealed of the Ebola virus. The test can be performed and interpreted with minimal training and the result is obtained in 20 minutes. A result semi-quantitative is obtained by quantifying the intensity of the color of a test line. Tests were carried out RT-PCR for the EVD in blood samples obtained by venipuncture with the kit review AltonaRealStarFilovirus (AltonaDiagnostics; Hamburg, Germany).

Fifteen of 131 patients tested positive for the EVD by RT-PCR, giving a prevalence of 11.5 %.  All the cases of EVD were identified by a VDR with a positive score on the test line for six or more, giving a 100% sensitivity and specificity corresponding was high, at 96.6 %.  The positive and negative predictive value for the prevalence in the population was 79.0 % and 100 %, respectively. The authors concluded that the DSTL EVD VDR is highly sensitive, specific, and performs well in a operating environment. A high sensitivity is essential for the acceptability of a diagnostic test for the EVD.

A screening test for high sensitivity such as this, which would prioritize the EVD suspected cases of high-risk for the insulation and the confirmatory diagnostic tests with a RT-PCR, reducing income not EVD in the EHUs. If the sensitivity is less, the positive cases of EVD could be discharged from inappropriately to hospital wards, with risk of nosocomial transmission later. This VDR could be used as a screening test using the rapid identification of cases of the EVD for improving the allocation of resources. The study was published on March 16, 2015, in the journal Eurosurveillance.