ABSTRACT
Objective To compare the complete mitochondrial genome sequences of two phenotypes of Paragonimus westermani isolated from Fujian Province with different sizes of metacercariae, and perform a phylogenetic analysis of various geographical isolates of P. westermani from Asia, so as to identify the possible genetic characteristics associated with the P. westermani phenotypes. Methods P. westermani metacercariae with different sizes (large metacercariae, 380–420 μm in diameter; small metacercariae, 320–340 μm) isolated from freshwater crabs were used to infect dogs, and the eggs and adult worms of P. westermani were collected from the dog stool samples and lung tissues. Then, the egg size and morphology were compared. In addition, genomic DNA was extracted from the adult worms of the two phenotypes of P. westermani and used for the PCR amplification to yield the complete mitochondrial genome sequence. Sequence structure and phylogenetic analyses were performed based on the complete mitochondrial genome of P. westermani. Results Following infection with large and small P. westermani metacercariae, the adult worms recovered from the dog lung had a thick body, and had oral and ventral suckers. The ventral sucker was located slightly in front of the midline of the body, and testes, ovary and vitelline gland were seen in the adult worms. Following fixation, the adults appeared oval, with an approximately 1.7∶1 of the length-width ratio. The length and width of the eggs isolated from the fecal samples of dogs infected with large and small P. westermani metacercariae varied significantly, and the large metacercariae produced bigger eggs than the smaller metacercariae. Based on the morphological features of adults and eggs and the ITS2 sequences, both phenotypes were identified as P. westermani. The complete mitochondrial genome sequence analysis of adults showed almost consistent sequences in the protein-coding region of the mitochondrial genome of adult worms derived from large and small metacercariae, with a major variation seen in the former non-coding region. Sliding window analysis revealed the most polymorphic region within the ND4 gene across the mitochondrial genome from various geographical isolates of P. westermani, and phylogenetic analysis showed that both phenotypes were clustered into the Chinese branch of P. westermani, which was close to the Japanese branch and distinct from the South/Southeast Asian branch. Conclusions The genetic distance between the phenotypes of P. westermani isolated from Fujian Province is near at a mitochondrial genome level, with no remarkable genetic differentiation seen; however, the mutation and structural changes in the non-coding region may result in the phenotypic variations. In addition, there is a distinct variation of the evolutionary rate in the mitochondrial coding genes, suggesting the selection of appropriate molecular markers during the phylogenic researches.
ABSTRACT
OBJECTIVE: To investigate the species and hosts of Paragonimus and its infection rate in eastern part of Zhenghe County, Fujian Province, so as to determine the local foci of Paragonimus. METHODS: The snails, crabs and stools of wild cats were collected for the examinations of cercariae, metacercariae and eggs of Paragonimus. The geographical and environmental conditions of the areas were also investigated. RESULTS: A total of 4 890 Pseudobythinella jianouensis snails and 1 035 Semisulcospira liberlina snails were examined, and the cercariae of Paragonimus were only found in P. jianouensis, with an infection rate of 0.10% (5/4 890). Bottapotamon zhengheensis sp. nov. as the second intermediate host of P. skrjabini, were examined, and the infection rate was 85.29% (29/34) and the average numbers of metacercariae per crab and per gram of crab tissues were 3.85 and 0.62, respectively. Thirty-six Sinopotamun fujianensis crabs, as the second intermediate host of P. westermani, were examined, and the infection rate was 38.89% (14/36) and the average numbers of metacercariae per crab and per gram of crab tissues were 6.43 and 0.03, respectively. The eggs of Paragonimus were detected in 1 of 2 muck specimens of wild cats. CONCLUSIONS: The data suggest that there is a focus of middle-to-high level of infection caused by P. westermani and P. skrjabini in the eastern part of Zhenghe County.
Subject(s)
Epidemics/veterinary , Paragonimiasis/veterinary , Animals , China/epidemiology , Feces/parasitology , Paragonimiasis/epidemiologyABSTRACT
<p><b>OBJECTIVE</b>To analyze the degrees on the epidemic foci of Angiostronglus cantonensis and to explore the measurement methods.</p><p><b>METHODS</b>Snails (Pila gigas) were collected from the spots of Wenzhou, Cangnan, Yongjia, Yueqing in Zhejiang province and Minhou, Changle, Ningde in Fujian province. The snails were examined microscopically in order to calculate their infection rates and the average worm number in the positive snails, then taking the product of multiplication of both values as infestation index.</p><p><b>RESULTS</b>The infection rates of the epidemic foci were 10.59% (9/85), 60.74% (181/298), 34.96% (79/226), 32.90% (76/231), 57.50% (184/320), 40.00% (82/205), 17.65% (12/68) and the rates of infectivity were 6.57, 183.54, 121.73, 93.45, 276.36, 76.08, 12.65, respectively.</p><p><b>CONCLUSION</b>The epidemic foci were divided into five ranks (super, high, mid-range, low and non-epidemic foci) according to the value of infestation index which ranked from > 75, 30-75, 5-29, < 5 to 0.</p>
