Quality assessment of malaria laboratory diagnosis in South Africa.

To assess the quality of malaria diagnosis in 115 South African laboratories participating in the National Health Laboratory Service Parasitology External Quality Assessment Programme we reviewed the results from 7 surveys from January 2000 to August 2002. The mean percentage incorrect result rate was 13.8% (95% CI 11.3-16.9%), which is alarmingly high, with about 1 in 7 blood films being incorrectly interpreted. Most participants with incorrect blood film interpretations had acceptable Giemsa staining quality, indicating that there is less of a problem with staining technique than with blood film interpretation. Laboratories in provinces in which malaria is endemic did not necessarily perform better than those in non-endemic areas. The results clearly suggest that malaria laboratory diagnosis throughout South Africa needs strengthening by improving laboratory standardization and auditing, training, quality assurance and referral resources.