Quality control measures for the serological diagnosis of hantavirus infections.

Background: With society's rapidly increasing mobility, patients infected with severe viral infections can become seriously ill at any place in Europe and elsewhere. Improving the diagnostics of these infections is the most important step in detecting the pathogens and dealing with them, and for this purpose, quality control measures are essential tools.

Objectives: To assess the diagnostic reality for rare hantavirus infections in Europe by (1) running a pre-evaluation panel (four samples, sent out in 1999) to optimise sample preparation and shipping procedure and afterwards (2) starting an External Quality Assurance (EQA) program (20 samples, sent out in 2001).

Study Design: All samples sent out had to be tested for the presence of specific IgG and IgM antibodies against hantavirus. For the pre-evaluation panel, four samples were distributed (two samples IgG+/IgM-, one sample IgG-borderline/IgM-, one sample IgG-/IgM-), for the EQA 20 samples (six samples IgG+/IgM+, eight samples IgG+/IgM-, one sample IgG-borderline/IgM-, five samples IgG-/IgM-). Thirteen laboratories took part in the pre-evaluation panel, 18 laboratories participated in the first EQA run.

Results: For the pre-evaluation panel, the participants reported correct results for 64% of the IgG-positive samples (85% excluding borderline-positive sample), and 92% for the IgG-negative sample. IgM testing was correctly negative in all laboratories. For the EQA, the participants reported correct results for 76% of the IgG-positive samples, and 97% correct results for the IgG-negative samples. For the IgM-positive samples, 53% correct results were reported, and 98% correct results for the IgM-negative samples.

Conclusions: The results presented here prove the importance of quality measures also for viruses only rarely suspected, like hantavirus, and they clearly demonstrate the need for improvement of the existing test systems.