ABSTRACT
Astroviruses are increasingly recognized as a cause of human gastroenteritis. Electron microscopy (EM) has been considered the "gold standard" method for diagnosis, but this approach is limited to a few laboratories. We evaluated a commercial enzyme immunoassay (EIA) (IDEIA Astrovirus, DAKO Diagnostika, Hamburg, Germany) for the direct detection of antigen in fecal samples. In comparison to EM, the assay scored 100% in sensitivity and specificity (n = 213; 26 positive samples) and reacted with strains representing all known serotypes. Over an 11-month period 4,211 stool samples from unselected German patients suffering from acute gastroenteritis were examined. Etiologically responsible microorganisms were found in 13.0% of cases, with astrovirus the third most common pathogen (1.2%) behind Salmonella spp. (2.9%) and Rotavirus (2.5%), representing 13.5% of all positive specimens. Norwalk-like viruses (NLV), fungi, and protozoa were not tested. In infants of < 2 years of age (n = 458) the incidence of astrovirus infection was significantly higher (2.8%) compared to children of 2-7 years of age (n = 578; 1.7%) and those of > 7 years of age (n = 3,175; 0.9%). The frequency revealed a peak in winter (mean November-February: 2.0% versus other months: 0.8%).
Subject(s)
Astroviridae Infections/diagnosis , Diarrhea/virology , Adolescent , Adult , Age Factors , Aged , Aged, 80 and over , Astroviridae Infections/complications , Astroviridae Infections/epidemiology , Child , Child, Preschool , Diarrhea/epidemiology , Enzyme-Linked Immunosorbent Assay/economics , Enzyme-Linked Immunosorbent Assay/methods , Enzyme-Linked Immunosorbent Assay/standards , Evaluation Studies as Topic , Feces/virology , Female , Germany/epidemiology , Humans , Incidence , Infant , Male , Mass Screening , Microscopy, Electron , Middle Aged , Reagent Kits, Diagnostic/standards , Seasons , Sensitivity and SpecificityABSTRACT
The presence of immunoglobulin E (IgE) antibodies was determined by using the immunosorbent-agglutination assay (ISAGA) with 611 serum samples from patients with different clinical conditions to evaluate its value for the serodiagnosis of acute Toxoplasma gondii infection. By analyzing 43 consecutively drawn serum samples from 10 pregnant women who seroconverted, we could show that specific IgE antibodies seem to appear early after infection and are usually present for less than 3 to 5 months. Therefore, we assumed that IgE antibodies seem to be detectable only during the acute or reactivated stage of infection. According to our studies, the IgE ISAGA has an overall sensitivity of only 79.5%, but a specificity of 98.0%, with positive and negative predictive values of 95.5 and 89.8%, respectively. Detection of IgE antibodies in immunosuppressed patients with reactivation of latent T. gondii infection correlates with disease activity. Despite these encouraging results, one must note that IgE antibodies were not detectable in 4 of 14 patients with very recent infection proven by seroconversion. Therefore, detection of IgE antibodies seems to correlate with early acute or reactivated toxoplasmosis, whereas negative IgE results do not exclude the possibility of the acute stage of toxoplasmosis.
