Discovery of Paragonimus proliferus in Northern Vietnam and their molecular phylogenetic status among genus Paragonimus

Abstract

During an epidemiological survey for Paragonimus and paragonimosis in northern Vietnam, we found extremely large excysted metacercariae (2.50 +/- 0.14 mm in length and 0.72 +/- 0.08 mm in width; mean +/- standard deviation of 20 samples) in mountainous crabs, Potamiscus mieni. Adult worms were successfully obtained by intraperitoneal injection with those large excysted metacercariae in a cat. Morphological and morphometric data of those large excysted metacercariae and the adult worms derived from them are identical to those of Paragonimus proliferus found in Yunnan province, China. However, when second internal transcribed spacer region and cytochrome oxidase subunit 1 gene sequences of those metacercariae and adult worms were compared with those of known Paragonimus spp. deposited in the GenBank, they were almost completely identical to those of Paragonimus hokuoensis metacercariae in China, of which adult worms have never been reported. This is the first record of P. proliferus in Vietnam and the first record from outside of China. Phylogenetic relationship between P. proliferus and P. hokuoensis is discussed.

Sequence analyses of ITS2 and CO1 genes of Paragonimus proliferus obtained in Yunnan province, China and their similarities with those of P. hokuoensis

“…Nine ITS2 and five CO1 sequences were successfully obtained from them, and those sequences were aligned with those of P. proliferus of the Vietnamese isolates (Doanh et al 2008) and several other related species within genus Paragonimus obtained from DNA database. The phylogenetic trees were constructed separately in two sequence data sets of ITS2 (Fig.…”

“…Although the metacercaria of P. proliferus is easily distinguishable from any other Paragonimus spp. by morphology, this species was found only in Yunnan Province, China until recent discovery in northern Vietnam (Doanh et al 2008). In comparison of the DNA sequences of ITS2 and CO1 genes of P. proliferus obtained in China with those of the Vietnamese isolates (Doanh et al 2008), two geographical isolates of P. proliferus are found to be genetically identical with each other.…”

“…by morphology, this species was found only in Yunnan Province, China until recent discovery in northern Vietnam (Doanh et al 2008). In comparison of the DNA sequences of ITS2 and CO1 genes of P. proliferus obtained in China with those of the Vietnamese isolates (Doanh et al 2008), two geographical isolates of P. proliferus are found to be genetically identical with each other. Significant genetic variance among geographic isolates was reported in P. westermani (Blair et al 2005;Iwagami et al 2008), P. skrjabini (Chen et al 2004;Blair et al 2005) and Paragonimus heterotremus (Le et al 2006).…”

“…The most prominent morphological feature of this species is the gigantic metacercariae, which is in fact the largest among any known Paragonimus metacercariae, and are mostly present as the excysted form in host crabs (Zhou 2004). Recently P. proliferus was found first time outside of China, in Shinho district, Lai Chau province, northern Vietnam (Doanh et al 2008). Surprisingly, DNA sequences of second internal transcribed spacer region (ITS2) and cytochrome oxidase subunit 1 gene (CO1) genes of P. proliferus metacercariae and adult worms found in Vietnam were identical (100% for ITS2 and >99% for CO1) with those of Paragonimus hokuoensis obtained in Mengla Country, Yunnnan, China deposited in the DNA database by Blair et al (2005).…”

Global status of fish-borne zoonotic trematodiasis in humans

“…In the mountain areas, local people consume lightly fried crabs and this constitutes a high risk of infection with lung fluke of Paragonimus spp. Doanh et al (2007Doanh et al ( , 2008Doanh et al ( , 2012 and Le et al (2006) isolated metacercariae of several Paragonimus species in crab and experimentally infected cats. The recovered flukes were collected and identified and two of these species were new.…”