Geographic distribution and gene sequencing of Paragonimus westermani in some areas of Guangdong Province

Objective To investigate the current distribution of Paragonimus westermani in Guangdong Province. Method Snails and crabs collected from mountain streams in regional survey sites were dissected to detect cercarial and metacercarial infec tions of P. westermani. Domestic cats and dogs artificially infected with the collected metacercariae were also dissected to detect adult worms of P. westermani. The COI and ITS2 gene sequences of those adult worms were compared with those of known Paragon imus specimen deposited in the GenBank. Results All of the first intermediate hosts in five survey sites of Liangkou,Nankun, Mountain,Dadong,Muxi,Guowu,were identified as Semisulcospira libertina,whose cercariae infection rates were 0.33%, 0.15%,0.058%,0.10%,and 0.05%,respectively;the second intermediate hosts in above five sites were all identified as Sino potamon denticulatum,whose metacercariae infection rates were 100%,100%,38.09%,55.36%,and 65.26%,respectively. The numbers of metacercariae in the five sites were 79.4,105.66,9.16,16.18,and 15.6 per positive crab,respectively,and 11.12,7.87,0.58,0.69,and 0.85 per gram of crab,respectively. All the metacercariae were identical to those of P. westermani. Adult worms and eggs of P. westermani were found in both reservoir hosts of domestic cats and dogs infected artificially. By comparing the COI genes of five representative samples from each survey site with that of Paragonimus #AF219379.21,AF540958.1 from GenBank,we found out the homology to be 99%,99%,99%,98%,and 99%,respectively. In addition,a comparison of the ITS2 gene sequences between the above five samples and Paragonimus #DQ836243.1,DQ351845.1,AB354217.1 from Gen Bank revealed 98%,99%,98%,98%,and 98% gene homology,respectively. Conclusion Two ultra-high and three high en demic areas of P. westermani are discovered in Guangdong Province. No obvious differences were found among the types of P. wes termani in the above five endemic areas.