Objective To investigate the population constitution and geographical distribution of Plasmodium vivax in China using molecular technique. Methods Blood spot filter paper samples with related epidemiological data were collected from vivax malaria patients living in malarious area of 10 provinces (autonomous region) in China. Semi nested or nested allelic specific PCR genotyping method was used to identify CSP genotypes, families and types of Plasmodium vivax of each isolate from these patients. Results Of 384 field isolates of Plasmodium vivax , 258 temperate zone family strains were identified,including 14 allelic variant genotypes spreading among 10 sampling provinces; allelic variants sized less than 731 bp were only seen in 5 provinces in southern China; 79 tropical zone family strains including 5 genotypes were also distributed in 5 provinces of southern China south to 25° N.lat; and 14 PV Type 2 strains including 2 genotypes were found in some areas of Hainan and Yunnan Provinces. In addition, 33 isolates from genotype-mixed infections were revealed. Conclusion At present, area north to 25° N.lat. of the country is the sole area prevalent for Plasmodium vivax family strains of temperate zone;there is overlapping distribution of P.v . of temperate zone family and tropical zone family of this parasite in the southern China south to 25° N.lat; where the most complex isolate constitution is in Yunnan and Hainan Provinces, and PV Type 2 strains have been found in some areas of the two provinces.Besides, there were 2 groups of genotype with distinct geographic distribution feature within the temperate zone family.
