ABSTRACT
Oncomelania hupensis is the only intermediate host of Schistosoma japonicum, and O. hupensis control is an important measure for schistosomiasis control. With the progress of national schistosomiasis control program, the prevalence of schistosomiasis is low in China; however, there are still multiple challenges for O. hupensis breeding and schistosomiasis transmission risk. Considering the target of the national schistosomiasis elimination program and environmental protection in the new era, the introduction of precision identification, precision interventions and precision assessment into O. hupensis control may facilitate the progress towards elimination of schistosomiasis in China.
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
Studies on the enzymology of snails are important in the study of molluscicidal mechanism.The alteration of activi-ties of enzymes after molluscicidal treatment was reported in large numbers of papers.This paper reviews the progress of studies on the enzymology of snails under the treatment of molluscicides.
ABSTRACT
Objective To investigate the knowledge and practice of residents about schistosomiasis prevention and control in endemic areas of Jingzhou City,Hubei Province after the disease transmission being controlled,so as to provide the valuable in-formation for formulating an efficient health education and intervention strategy.Methods The residents were selected by using the cluster sampling method and investigated with questionnaires in Jiangling County and Gong'an County,Jingzhou City,Hu-bei Province,and the data were analyzed by using the descriptive analysis method,Chi-square tests and logistic regression.Re-sults In a total,826 available questionnaires were obtained with 100% of valid rate.Among them,97.0% of the interviewee knew schistosomiasis,and 86.3% knew that the infection happened by contacting water containing cercariae.The residents in el-der age(41-84 years)had higher awareness rates than the residents in lower age(6-17 years),about the regions of epidemic area(χ 2=57.860),infection route of schistosomiasis(χ 2=87.045),advanced schistosomiasis symptoms(χ 2=27.268)and On-comelania hupensis being as intermediate host(χ 2=55.856)(all P<0.05).The males had higher awareness rates of epidemic areas than the females(χ2=13.442,P<0.05).For personal behavior,36.6% of the interviewee had experience of contacting lake or pond water many times a day,and 66.5% had the willingness to participate in schistosomiasis health education.Conclu-sion In the investigation areas,Jiangling County and Gong'an County,the awareness rates of the residents about schistosomia-sis prevention and control are higher,and we should strengthen the health education and behavior intervention,especially in the students of middle and primary schools to help them have the self-protection ability efficiently.