Molecular Characterization of Paragonimus westermani from South India

Paragonimus westermani is the most common lung fluke infecting humans in Asia. This study aimed to molecularly characterize adult P. westermani from the south India (Kerala) using ITS-2, partial 28 S rDNA and partial cox1 gene sequences.

Adult flukes were recovered from the lungs of a tiger (Panthera tigris) (n = 10), a jungle cat (Felis chaus) (n = 6) and a domesticated dog (Canis familiaris) (n = 4). ITS-2, partial 28 SrDNA and partial cox1 gene sequences were amplified by polymerase chain reaction and a concatenated phylogenetic tree was constructed with these three marker sequences. Intra-species and inter-species genetic distances were calculated, and haplotype network analysis was performed using partial cox1 gene.

Phylogenetic analysis based on the concatenated tree showed that Kerala isolates formed P. westermani complex with other isolates of P. westermani from India and from other countries. The Kerala isolates were genetically closer to metacercaria morphotype 2 of P. westermani. However, the genetic distance was higher among Indian isolates, indicating significant genetic variation among P. westermani within the complex. In addition, India also exhibited the highest number of haplotypes (n = 8).

Concatenated phylogenetic analysis of the Indian isolates of P. westermani show them to form P. westermani complex. The parasite exhibits high genetic distance with a large number of haplotypes. Further epidemiological studies are needed to understand its genetic variability. No sub-populations have been recognized in P. westermani based on the presented molecular data.