Specificity and sensitivity of diagnostic rapid tests for the acute infections with Hantaviruses

Puumala (PUUV) and Dobrava (DOBV) viruses are causative agents of hemorrhagic fever with renal syndrome (HFRS) in Croatia. Whole Croatia except the coast and islands is HFRS endemic region. Although many diagnostic tests are now developed for the serological confirmation of acute HFRS, there is still need for the accurate rapid test. During the greatest HFRS outbreak in Croatia in 2002, we aimed to evaluate rapid immunochromatographic test for the detection of specific IgM antibodies to PUUV and DOBV. For the preliminary, retrospective evaluation, serum samples of 105 acute HFRS patients were tested with five-minutes, POC PUUMALATM and POC DOBRAVATM point-of-care tests (ERILAB, Finland). HFRS diagnosis has been previously confirmed with one of the standardized techniques like IgM and IgG ELISA tests and IFA test for the detection of the specific antibodies to hantaviruses. Additionally, in some cases diagnosis was confirmed by RT-PCR. Further, both tests were tested for the specificity and sensitivity with the sera of acute HFRS patients infected with PUUV or DOBV. To evaluate the specificity of both rapid tests, we tested sera of patients with confirmed other acute zoonozis in Croatia: leptospirosis, tick borne encephalitis (TBE) and borreliosis. To exclude the subjectivity in the interpretation, several evaluators interpreted the tests and differences among them were statistically tested using 2.test. Retrospective evaluation showed that in about 80% of patients acute HFRS diagnosis was confirmed with the rapid immunochromatographic tests only. There were no statistical differences among the evaluators who interpreted the POC PUUMALATM, although the less subjectivity was found when they interpreted tests one hour after preparation. For the evaluation of POC DOBRAVATM test, additional evaluation is necessary to confirm the specificity and sensitivity of the test when tested in Croatian patients. Our results showed that sera of the patients with acute leptospirosis, TBE or borreliosis did not cross-react with POC PUUMALATM and POC DOBRAVATM point-of-care tests. The rapid immunochromatographic test is useful tool for the diagnosis of acute HFRS especially during the outbreak. However, the final diagnosis should be confirmed with additional tests.