Avaliação da utilização de ensaio imunocromatográfico para o diagnóstico e estudo de prevalência da hepatite A

Abstract

Abstract: The diagnosis of infection by the hepatitis A virus (HAV) through high sensitivity and specificity tests can lead an earlier and more accurate diagnosis, improving the prognosis of the disease. It should also be mentioned that a more precise diagnosis can become more reliable epidemiological studies and as a basis for the production of more effective control and eradication programs. The aim of this study was to evaluate an immunochromatographic test in outbreaks and epidemiological studies of prevalence, screening candidates for vaccination and post-vaccination surveillance programs. For this purpose, 342 samples from patients of four different groups were analyzed: (I) samples from blood donors (n=96), (II) samples from individuals vaccinated for hepatitis A (n=46), (III) samples from hepatitis A outbreaks (n=103) and (IV) samples from sporadic cases of hepatitis A (n=97). These samples were submitted to the rapid test SD BIOLINE HAV IgG/IgM and all results of the rapid test were compared to the results of HAV enzyme immunoassay (EIA) that is the gold standard to detect antibodies against HAV. The results obtained for the group I showed that, 33.3% (32/96) were positive for anti-HAV IgG using the rapid test and 67.7% (65/96) were positive for IgG anti-HAV by EIA. At group II, 71.7% (33/46) of the samples were positive for anti-HAV IgG by EIA and none of them (0/33) was reactive by rapid test. Groups III and IV were tested for the presence of anti-HAV IgG and anti-HAV IgM antibodies Regarding anti-HAV IgG antibodies, at the group III 60.1% (62/103) and 81.5% (84/103) were positive by the rapid test and in EIA, respectively. For IgM anti-HAV antibodies, 45.6% (47/103) and 47.5% (49/103) of the samples were positive through the rapid test in EIA, respectively. For the group IV, regarding the evaluation of anti-HAV IgG antibodies, 61.8% (60/97) were positive by the rapid test, and 75.2% (73/97) were positive on EIA and for antibodies anti-HAV IgM, 45.3% (44/97) of the samples were positive to the rapid test, and 46.9% (46/97) were positive in EIA. The sensitivity and specificity of a rapid test for group I for detection of anti-HAV IgG antibodies were 49.23% and 100%, respectively. In group III, for IgM anti-HAV sensitivity and specificity were 95.92% and 100%, respectively, and anti-HAV-IgG the sensitivity and specificity were 78.79% and 21.62%, respectively. In group IV, in relation to anti-HAV IgM sensitivity and specificity were 93.48% and 98.04%, respectively, and anti-HAV-IgG the sensitivity and specificity were 79.45% and 91.67%, respectively The level of agreement according to the Kappa index (k) was considered weak in groups I and III, and IV group good at both tested for anti-HAV IgG marker. The groups tested with anti-HAV IgM marker, we obtained a good agreement for the IV and excellent group for the group III. In testing of samples from groups III and IV by nested-PCR, for the group III obtained 47.5% (49/103), 45.5% (47/103) and 100.0% (103/103) of the samples ELISA reagents for IgM anti-HAV, rapid test and nested PCR. Regarding the group IV, it obtained 46.9% (46/97) of samples in ELISA reagents, 45.3% (44/97) of the rapid test reagents samples and 40.2% (39/97) of samples result reagent by nested-PCR. In conclusion, the test proved to be suitable for the detection of anti-HAV IgM antibodies, indicating their applicability for the diagnosis of hepatitis A outbreaks and sporadic cases. However, the poor performance of the rapid test for anti-HAV IgG detection showed that it needs to be improved for studies on past infection detection and response to vaccination