Prevalence of human soil-borne nematode infections in Yunnan Province: a cross-sectional study in 2015 / 中国血吸虫病防治杂志

Objective To investigate the current prevalence of human soil-borne nematode infections in Yunnan province, so as to provide the scientific evidence for formulating the soil-borne nematodiasis control strategy in the province. Methods In 2015, a total of 20 survey sites were sampled in 10 counties (cities) of Yunnan Province using the stratified cluster random sampling method. Stool samples were collected from all local permanent residents at ages of one year and older in each survey site, and the soil-borne nematode eggs were identified using the modified Kato-Katz technique and the egg number was counted. In addition, the hookworm species was identified using the filter-paperculture method, and Enterobius vermicularis eggs were detected using the cellophane tape method in children at ages of 3 to 6 years. Results A total of 5 067 residents received stool examinations, and 950 residents were detected with soil-borne nematode infections, with an overall prevalence rate of 18.75%. The prevalence of Ascaris lumbricoides, Trichuris trichura and hookworm was 7.52%, 8.47% and 9.02%, respectively. Among 446 children detected using the cellophane tape method, 5 children were detected with E. vermicularis infections. Among the 160 residents with hookworm infections, there were 139 residents with Necator americanus infections (86.88%), 16 with A. duodenale infections (10.00%) and 5 with mixed infections (3.12%). Mild A. lumbricoides (67.98%, 259/381), T. trichura (88.58%, 380/429) and hookworm infections (94.53%, 432/457) were predominant. Among the four ecological zones, the highest prevalence of human soilborne nematode infections was found in the East Tibet-South Sichuan Ecological Zone (31.79%), and among the 10 survey counties (cities), the greatest prevalence was seen in Gongshan Derung and Nu Autonomous County (50.13%), while the lowest prevalence was found in Ninglang Yi Autonomous County (0.40%). The prevalence of human soil-borne nematode infections was 5.67% (43/759), 26.67% (610/2 287) and 14.70% (297/2 021) in high-, moderate- and low-economic-level regions, respectively. There were no significant differences in the prevalence of human soil-borne nematode infections in terms of ecological regions, survey counties (cities) or economic development levels (χ2 = 342.20, 814.60 and 201.34, all P < 0.05). There was no significantdifference in the prevalence of human soil-borne nematode infections between male (18.21%, 441/2 422) and female residents (19.24%, 509/2 645) (χ2 = 0.89, P > 0.05), and soil-borne nematode infections were detected in residents at all age groups, with the greatest prevalence found in residents at ages of 1 to 9 years (25.88%). In addition, the highest prevalence of soil-borne nematode infections was seen in residents with the Dulong Ethnic Minority (82.09%), in preschool children (25.06%) and in illiterate residents (24.80%), and there was no age-, ethnicity-, occupation- or education level-specific prevalence of soil-borne nematode infections detected (χ2 = 46.50, 1 016.96, 36.33 and 52.43, all P < 0.05). Conclusions The prevalence of human soil-borne nematode infections remains high in Yunnan Province. The management of soil-borne nematodiasis requires to be reinforced among low-age children, farmers, old people and residents with low educations levels or ethnic groups.

[Genotyping and polymorphism analysis of cytochrome c oxidase subunit â gene of Pomacea canaliculata from Lincang City in Yunnan Province].

OBJECTIVE: To analyze the genetic diversity of Pomacea canaliculata based on the mitochondria DNA cytochrome c oxidase subunit Ⅰ (mtDNA COⅠ) gene as a molecular marker in Lincang City of Yunnan Province, so as to provide the scientific data for monitoring Angiostrongylus cantonensis in local areas. METHODS: The genotypes and polymorphisms of 38 specimens of P. canaliculata collected from Mengding Town of Lincang City were analyzed by sequencing COⅠ gene. The phylogenetic tree and genetic distances were produced based on the haplotypes from GenBank and the present study by using the neighbourjoining method with the software MEGA version 6.06. RESULTS: Totally 31 sequences were acquired in the present study and they produced 3 unique haplotypes. Haplotype 1 showed a higher frequency compared to the others and it accounted for 83.9 % (26/31). The data showed that the least genetic distances ranged from 0 to 0.052 between P. canaliculata and 3 haplotypes, as well as the largest genetic distances ranged from 0.021 to 0.239 between Pila conica and 3 haplotypes. Otherwise, the analysis of the phylogenetic trees based on COⅠ gene sequences of P. canaliculata indicated that all of 3 haplotypes clustered into one big clade with that from Japan (GenBank accession number: AB433769), China (GenBank accession number: KT313034) and USA (GenBank accession number: EU523129), which owned the closet relationship amongst them. Their genetic relationships were distantly related to the GenBank's reference sequences of P. insularum (GenBank accession number: EF514942), P. camena (GenBank accession number: EF515059) and so on. CONCLUSIONS: There is a P. canaliculata species in Lincang City of Yunnan Province as well as a high genetic diversity amongst the acquired 3 haplotypes in this study.

Genotyping and polymorphism analysis of cytochrome c oxidase subunit Ⅰgene of Pomacea canaliculata from Lincang City in Yunnan Province / 中国血吸虫病防治杂志

Objective To analyze the genetic diversity of Pomacea canaliculata based on the mitochondria DNA cytochrome c oxidase subunitⅠ(mtDNA COⅠ)gene as a molecular marker in Lincang City of Yunnan Province,so as to provide the scien-tific data for monitoring Angiostrongylus cantonensis in local areas. Methods The genotypes and polymorphisms of 38 speci-mens of P.canaliculata collected from Mengding Town of Lincang City were analyzed by sequencing COⅠgene.The phylogenet-ic tree and genetic distances were produced based on the haplotypes from GenBank and the present study by using the neighbour-joining method with the software MEGA version 6.06. Results Totally 31 sequences were acquired in the present study and they produced 3 unique haplotypes.Haplotype 1 showed a higher frequency compared to the others and it accounted for 83.9 % (26/31).The data showed that the least genetic distances ranged from 0 to 0.052 between P.canaliculata and 3 haplotypes,as well as the largest genetic distances ranged from 0.021 to 0.239 between Pila conica and 3 haplotypes.Otherwise,the analysis of the phylogenetic trees based on COⅠgene sequences of P.canaliculata indicated that all of 3 haplotypes clustered into one big clade with that from Japan(GenBank accession number: AB433769),China(GenBank accession number: KT313034)and USA(GenBank accession number:EU523129),which owned the closet relationship amongst them.Their genetic relationships were distantly related to the GenBank's reference sequences of P.insularum(GenBank accession number:EF514942),P.cam-ena(GenBank accession number: EF515059)and so on. Conclusion There is a P. canaliculata species in Lincang City of Yunnan Province as well as a high genetic diversity amongst the acquired 3 haplotypes in this study.

[Investigation of soil - transmitted nematode infections in Xiding Township, Menghai County, Yunnan Province].

OBJECTIVE: To understand the status of soil-transmitted nematode infections in Xiding Township, Menghai County, Yunnan Province, so as to provide the reference for formulating the strategy of soil-transmitted nematodosis control. METHODS: Soil-transmitted nematode eggs in feces were detected by the Kato-Katz method, and the eggs of Enterobius vermicularis were detected by the cellophane tape method in children. The soil samples were collected from vegetable, fruit and other crop fields of 15 residents randomly to detect hookworm. RESULTS: The stool samples from 1 002 residents were examined and the soil -transmitted nematode infection rate was 20.06% (201/1 002). The infection rates of hookworm, Ascaris lumbricoides and Trichuris trichura were 18.96% (190 cases), 1.70% (17 cases) and 0.90% (9 cases) respectively. The percentages of people with light infection of hookworm, A. lumbricoides and T. trichura were 97.37% (185/190), 88.24% (15/17) and 100% (9/9) respectively. No infection of E. vermicularis was found. Fifteen soil samples were tested, and no hookworm was found in the soil. CONCLUSIONS: The infection rate of soil-transmitted nematode in Xiding Township, Menghai County is high, but the infectiosity is light. The control and monitoring of soil-transmitted nematodosis should be strengthened in this area.