Screening for different genotypes of Echinococcus granulosus within China and Argentina by single-strand conformation polymorphism (SSCP) analysis.

Single-strand conformation polymorphism (SSCP) analysis was employed for the direct visual display of genetic variability in mitochondrial DNA (mtDNA) fragments within and among populations of Echinococcus granulosus from the People's Republic of China and from Argentina. Fragments of the NADH dehydrogenase I gene (NDI) and the cytochrome c oxidase subunit I (COI) were individually amplified from parasite DNA by polymerase chain reaction, denatured and subjected to SSCP analysis. Using NDI and COI fragments, samples representing different genotypes could be readily identified based on characteristic SSCP profiles. The results demonstrate the utility of SSCP for the direct visual display of nucleotide variation in mtDNA of E. granulosus prior to DNA sequence analysis. The approach compares favourably with existing genotyping procedures and provides a reliable and technically reproducible method for the routine laboratory identification of Echinococcus isolates.

Genetic variation and epidemiology of Echinococcus granulosus in Argentina.

Polymerase chain reaction-ribosomal ITS-1 DNA (rDNA) restriction fragment length polymorphism (PCR-RFLP) analysis and sequencing of the mitochondrial cytochrome c oxidase subunit 1 (CO1) and NADH dehydrogenase 1 (ND1) genes were used to characterize 33 Echinococcus granulosus isolates collected from different regions and hosts in Argentina, and to determine which genotypes occurred in humans with cystic hydatid disease. The results of the study demonstrated the presence of at least 4 distinct genotypes; the common sheep strain (G1) in sheep from Chubut Province and in humans from Río Negro Province, the Tasmanian sheep strain (G2) in sheep and 1 human from Tucumán Province, the pig strain (G7) in pigs from Santa Fe Province and the carnel strain (G6) in humans from Río Negro and Buenos Aires Provinces. The finding that pigs harboured the pig strain and the occurrence of the Tasmanian sheep strain has considerable implications for the implementation of hydatid control programmes due to the shorter maturation time of both strains in dogs compared with the common sheep strain. Furthermore, this is the first report of the presence of the G2 and G6 genotypes in humans which may also have important consequences for human health.