Abstract:ABSTRACT: Objective To determine the epidemiological distribution of Paragonimus in northern Guangdong Province. Method Cercariae and metacercariae of Paragonimus were isolated from freshwater snails and crabs, randomly collected at every study sites in northern Guangdong Province. Adult worms were obtained from experimentally infected cats and dogs with those metacercariae. The gene sequences of cytochrome c oxidase subunit 1 (COI) and second internal transcribed spacer (ITS2) region from adult worms were aligned with those of Paragonimus spp. deposited in GenBank database. Result Infection rates for the metacercariae of Euparagonimus cenocopiosus in freshwater crabs, Sinopotamon pinheense, recorded at five of the six sites studied, were as follows: 74.54% (41/53) at Lidong, 68.91% (32/47) at Souliyuan, 77.77% (24/32) at Xiadonghe, 76.92% (40/52) at Daping, and 81.5% (22/27) at Xiaokeng, respectively. The COI gene sequences of adult worms derived from cats and dogs infected with metacercariae from the above five sites shared 99.5%, 100%, 99.5%, 99.5%, and 100% homology with those from Euparagonimus cenocopiosus in GenBank, and the ITS2 gene was 100% identical. At Dadong, however, 38.09% (32/84) of crabs (Sinopotamon pinheense) were infected with the metacercariae of Paragonimus westermani, and 0.058% (1/1,700) of snails (Semisulcospira Libertina) was infected with cercariae of Paragnonimus westermani. The COI gene sequence of adult worms from Dadong was 100% identical to that of Paragnonimus westermani in the GenBank, and the ITS2 gene sequence was 99.5% identical . Conclusion Five new high endemic areas of Euparagonimus cenocopiosus, with Sinopotamon pinheense as second intermediate host, and one new high endemic area of Paragnonimus westermani, utilizing Semisulcospira Libertina and Sinopotamon pinheense as first and second intermediate hosts, were discovered in northern Guangdong .
KEY WORDS:Paragonimus;cercariae ;metacercariae ;infection rate ;Semisulcospira libertine ;Sinopotamon pinheense