Commercially available rapid diagnostic tests for diagnosing chikungunya virus appear to perform poorly in terms of specificity and sensitivity, according to recent findings.
“The increasing threat of [chikungunya virus] emergence in temperate regions and the need to anticipate possible outbreaks of [chikungunya virus] infection are presenting a challenge to the current level of diagnostic preparedness,” researchers wrote in Emerging Infectious Diseases.
In the study, the researchers assessed the utility of four commercially available blood tests approved by the European Commission for the detection of chikungunya virus. Two of these tests were rapid detection tests (RDTs) for chikungunya immunoglobulin M antibodies and included the SD Bioline Chikungunya IgM (Standard Diagnostics Inc.) and the OnSite Chikungunya IgM Combo Rapid Test (CTK Biotech). The remaining two tests were enzyme-linked immunosorbent assays (ELISAs) screening for chikungunya IgM and IgG, and they were manufactured by Euroimmun and IBL International, respectively.
The researchers acquired two sets of serum samples that had been sent to the French Armed Forces Biomedical Research Institute (IRBA) for arbovirus testing between 2005 and 2014. Panel A, which consisted of 23 samples, was assayed in two National Reference Centers for Arboviruses laboratories. The samples were analyzed through two in-house ELISAs and a neutralization test. Panel B was tested via in-house IRBA techniques. Due to limited sample volumes, the researchers used panel A to test the commercial kits, whereas panel B was used only when test results from panel A yielded specificity and sensitivity higher than 70%.
The researchers found that, upon using the two RDTs to test panel A samples plus serum samples infected with Mayaro virus and O’nyong-nyong virus, these tests did not detect either virus. The SD Bioline RDT demonstrated poor sensitivity (30%) and specificity (73%) in the detection of chikungunya in the panel A samples, with a 39% rate of false-negative results and 57% rate of false-positive results. The RDT from CTK Biotech had 93% specificity and 20% sensitivity in the panel A samples, with a 36% rate of false negatives and a 33% rate of false positives. Because the RDTs were determined to be ineffective by the panel A test results, the panel B samples were not tested.
The IgM and IgG ELISAs also were used to assay samples from panel A plus blood samples infected with Mayaro virus and O’nyong-nyong virus. Because the results of these tests had specificity and sensitivity of more than 70%, the researchers also tested panel B.
Both ELISAs detected IgM and IgG antibodies for O’nyong-nyong virus. Additionally, the Euroimmun ELISA detected IgG but not IgM for Mayaro virus, whereas the IBL International ELISA detected neither IgG nor IgM antibodies. The IBL International ELISA yielded a specificity of 88% (IgM) and 96% (IgG), and a sensitivity of 79% (IgM) and 52% (IgG). In the detection of IgM, the IBL International ELISA had a 12% rate of false-positive results and a 21% rate of false negatives.
The Euroimmun ELISA had a specificity rate of 82% (IgM) and 95% (IgG), and a sensitivity of 85% (IgM) and 88% (IgG). In detecting IgM, the Euroimmun ELISA kit had an 18% false-positive rate and a 15% false-negative rate.
According to the researchers, these findings indicate that the RDTs evaluated should not be used in a clinical setting; they added that while the ELISAs performed better, their rates of false-positive and false-negative results are “non-negligible.” They also noted that more effective chikungunya tests are needed.
“If the current outbreak of [chikungunya] infection in the Americas follows the same trend as that seen in the 2005 Réunion Island outbreak, increased circulation of the virus can be expected, and diagnostic laboratories must be prepared,” the researchers wrote. “Our evaluation was a pilot study using a small number of samples, but the findings show the importance of evaluating commercial diagnostic kits and published protocols before using such tools in clinical settings.”
Disclosure: The researchers report no relevant financial disclosures.