Quality assurance of the serologic diagnosis of Chagas' disease.

A quality assurance program of the Chagas' disease laboratory network of Argentina has been conducted by the National Reference Center since 1988, with the aim of assessing the reliability of serologic test results. Chagas' disease is endemic in Argentina, but the prevalence of seropositivity for Trypanosoma cruzi among 18- to 20-year-old men decreased from 5.8% in 1981 to 1.8% in 1994. About 600 laboratories form the Chagas' disease laboratory network, with main central laboratories in each of the 24 provinces in Argentina. The quality assurance program promotes regular use of good laboratory practice and internal and external quality control to improve performance of the participants; it also provides technical assistance and guidelines. Eventual corrective measures are discussed in workshops. Results of the first external evaluation by proficiency testing of serum panels and confirmation of results for 58 of the main laboratories reveal that from 1988 to 1994 the rate of agreement has increased.