Reliability of skin smear results: experiences with quality control of skin smears in different routine services in leprosy control programmes.

The quality control of skin smears is an important tool in improving the diagnosis of leprosy. We evaluated the skin smears sent to us by 50 laboratory technicians of 29 projects in Asia, Africa and South America. The skin smears were judged according to taking, staining and reading. The correlation was altogether satisfactory. In reading, a low correlation was found in 11% (42 slides) and it was seen that the highest percentage of low correlations was found in the false negative smears. The evaluation of cases with a low correlation leads to the conclusion that using the new WHO classification of 1988 will not reduce the number of incorrectly classified cases. From 42 slides showing a low correlation of their BI results, 7% led to a different classification (paucibacillary instead of multibacillary or vice versa) according to the WHO definition given in 1982, but 8% according to the 1988 WHO definition.