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We aimed to assess the risks of
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Humans , China , Cryptosporidiosis/microbiology , Cryptosporidium/isolation & purification , Giardia/isolation & purification , Giardiasis/microbiology , Risk Assessment , Water Microbiology , Water Supply/statistics & numerical dataABSTRACT
Objective To detect the chloroquine-resistant molecular marker polymorphisms in Plasmodium falciparum imported into China, investigate the mutation types of P. falciparum chloroquine resistant transporter (Pfcrt) gene at positions 72 to 76, and analyze the specificity of the P. falciparum specimens with different origins. Methods A total of 674 filter paper blood samples were collected from the National Malaria Diagnosis Reference Laboratory of China in 2012 and 2018. The amino acid po- sitions 72 to 76 of the Pfcrt gene on chromosome 7 were amplified using nested PCR assay and sequenced, and the sequencing results of the target gene fragment and the geographical region-specific prevalence of the mutations in the Pfcrt gene were analyzed. Results Among the 674 imported P. falciparum malaria cases in China in 2012 and 2018, 99.5% (644/674) were from Africa, which were predominantly from western and central Africa (80.4%, 518/644), and 4.5% (30/674) from Southeast Asia and Oceania (Papua New Guinea). A total of 4 site mutations (C72S, M74I, N75E and K76T) and 5 haplotypes (CVMNK, CVIET and SVMNT and two mixed types) were identified, with haplotypes CVMNK and CVIET present in parasites of both African and Southeast Asian origins, SVMNT detected in Southeast Asia (Myanmar) and Papua New Guinea isolates, the mixed type of haplo- types CVMNK/CVIET detected in P. falciparum of African and Southeast Asian origins, and the mixed type of haplotypes CVMNK/SVMNT detected only in the Myanmar isolate. Most P. falciparum parasites of the African origin carried the wild-type Pfcrt allele (77.7%, 478/615), and 68.0% (17/25) of the P. falciparum parasites of the Southeast Asian and Papua New Guinea or- igins harbored chloroquine resistant molecular markers (χ2 = 28.5, P < 0.05). The constituent ratio of the wild- and mutant-type Pfcrt allele varied in different geographical regions of Africa (P < 0.01), and the lowest prevalence of the wild-type Pfcrt allele was seen in western Africa. Conclusion Among the 674 imported malaria cases in China in 2012 and 2018, the P. falciparum imported from Sotheast Asia habors a higher proportion of resistance to chloroquine and a higher molecular polymophism at ami- no acid positions 72 to 76 of the Pfcrt gene than the parasite of the African origin.
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Objective To compare the performance of modified Kato-Katz thick smear method (KK method) and PCR assay in field detection of Clonorchis sinensis in human fecal samples, which provides insight into the selection of tools for detecting C. sinensis. Methods Based on the epidemiological investigation of human C. sinensis infections in Tengxian County of Guangxi Zhuang Autonomous Region in 2016, a total of 133 fecal samples were randomly selected and stored at -20 ℃. All fecal samples were detected for C. sinensis infection using KK method and PCR assay, and the detection rate was compared between the two techniques. In addition, Kappa test was used to evaluate the consistency between the two methods. Results Among all fecal samples, the overall detection rate of C. sinensis was 77.44% (103/133), and the detection rate was significantly higher by PCR assay (70.68%, 93/133) than by KK method (57.14%, 76/133) (χ2 = 26.15, P < 0.01). There were 88.16% (67/76) of the microscopy-positive fecal samples positive for PCR assay, and 47.37% (27/57) of the microscopy-negative fecal samples positive for PCR assay. The detection rate of C. sinensis by PCR assay (94.74%, 18/19) was higher in fecal samples with EPG of > 1 000 than in samples with EPG of < 1 000 (85.96%, 49/57) (χ2 = 1.05, P = 0.436). The consistency of the detection rate of C. sinensis was moderate between the KK method and PCR assay (Kappa = 0.73). Conclusions The detection rate of C. sinensis by PCR assay is significantly higher than by KK method. In low-endemic areas of C. sinensis infections, the combination of KK method and PCR assay is suggested, so as to improve the detection rate.
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Objective To compare the performance of modified Kato-Katz thick smear method (KK method) and PCR assay in field detection of Clonorchis sinensis in human fecal samples, which provides insight into the selection of tools for detecting C. sinensis. Methods Based on the epidemiological investigation of human C. sinensis infections in Tengxian County of Guangxi Zhuang Autonomous Region in 2016, a total of 133 fecal samples were randomly selected and stored at -20 ℃. All fecal samples were detected for C. sinensis infection using KK method and PCR assay, and the detection rate was compared between the two techniques. In addition, Kappa test was used to evaluate the consistency between the two methods. Results Among all fecal samples, the overall detection rate of C. sinensis was 77.44% (103/133), and the detection rate was significantly higher by PCR assay (70.68%, 93/133) than by KK method (57.14%, 76/133) (χ2 = 26.15, P < 0.01). There were 88.16% (67/76) of the microscopy-positive fecal samples positive for PCR assay, and 47.37% (27/57) of the microscopy-negative fecal samples positive for PCR assay. The detection rate of C. sinensis by PCR assay (94.74%, 18/19) was higher in fecal samples with EPG of > 1 000 than in samples with EPG of < 1 000 (85.96%, 49/57) (χ2 = 1.05, P = 0.436). The consistency of the detection rate of C. sinensis was moderate between the KK method and PCR assay (Kappa = 0.73). Conclusions The detection rate of C. sinensis by PCR assay is significantly higher than by KK method. In low-endemic areas of C. sinensis infections, the combination of KK method and PCR assay is suggested, so as to improve the detection rate.
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Objective To compare the genetic diversity of imported Plasmodium falciparum by Polyα and TAA87 microsatellite markers in Southeast Asian and African geographical isolates. Methods Ninety-two and 126 filter paper samples from patients infected with P. falciparum from Southeast Asia (Myanmar) and Africa (Ghana) were collected, respectively. Two neutral microsatellite loci, Polyα and TAA87 were amplified by PCR. The length of PCR fragments was detected by capillary electrophoresis. The allele frequency and expected heterozygosity (He) were calculated by Excel 2010 and GenALEx 6.0 software. Results A total of 146 P. falciparum samples were analyzed as single infection samples with a total of 26 alleles in locus Polyα and 12 alleles in locus TAA87. The mean He value of the two loci was 0.86 ± 0.02. Ten alleles in locus Polyα and 8 alleles in locus TAA87 were distributed in Myanmar isolates, with the He values of 0.86 and 0.81 respectively. Fifteen alleles in locus Polyα and 11 in locus TAA87 were detected in Ghana isolates, with the He values of 0.91 and 0.86 respectively. In addition, the haplotype of 174 bp (Polyα) and 113 bp (TAA87) were only detected in Myanmar isolates with more than 17% gene frequency, whereas they were absent in Ghana isolates. Conclusions The two different geographical sources of imported P. falciparum strains have different allele frequencies and haplotypes at the two neutral microsatellite markers, Polyα and TAA87. Therefore, these two microsatellite loci may be considered as the potential molecular marker candidates for identifying P. falciparum strains with different geographical sources.
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Objective To compare the genetic diversity of imported Plasmodium falciparum by Polyα and TAA87 microsatellite markers in Southeast Asian and African geographical isolates. Methods Ninety-two and 126 filter paper samples from patients infected with P. falciparum from Southeast Asia (Myanmar) and Africa (Ghana) were collected, respectively. Two neutral microsatellite loci, Polyα and TAA87 were amplified by PCR. The length of PCR fragments was detected by capillary electrophoresis. The allele frequency and expected heterozygosity (He) were calculated by Excel 2010 and GenALEx 6.0 software. Results A total of 146 P. falciparum samples were analyzed as single infection samples with a total of 26 alleles in locus Polyα and 12 alleles in locus TAA87. The mean He value of the two loci was 0.86 ± 0.02. Ten alleles in locus Polyα and 8 alleles in locus TAA87 were distributed in Myanmar isolates, with the He values of 0.86 and 0.81 respectively. Fifteen alleles in locus Polyα and 11 in locus TAA87 were detected in Ghana isolates, with the He values of 0.91 and 0.86 respectively. In addition, the haplotype of 174 bp (Polyα) and 113 bp (TAA87) were only detected in Myanmar isolates with more than 17% gene frequency, whereas they were absent in Ghana isolates. Conclusions The two different geographical sources of imported P. falciparum strains have different allele frequencies and haplotypes at the two neutral microsatellite markers, Polyα and TAA87. Therefore, these two microsatellite loci may be considered as the potential molecular marker candidates for identifying P. falciparum strains with different geographical sources.
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<p><b>OBJECTIVE</b>Pigs, as hosts of zoonotic Cryptosporidium species/genotypes, are domestic animals with public health significance. The present study was to characterize the infection rate and species/genotype of Cryptosporidium in pre-weaned and post-weaned pigs from Shanghai and Shaoxing, China.</p><p><b>METHODS</b>A total of 208 fecal samples (42 from pre-weaned piglets, and 166 from post-weaned pigs) were examined by nested PCR of the 18S rRNA gene and analyzed by phylogenetic DNA fragment sequencing of secondary PCR products.</p><p><b>RESULTS</b>Infection was detected in 79 samples (19/42 pre-weaned piglets, and 60/166 post-weaned pigs). C. suis (14/79) and Cryptosporidium pig genotype II (65/79) were identified; piglets were more susceptible to the former (13/14) and post-weaned pigs to the latter (59/65).</p><p><b>CONCLUSION</b>Infection of Cryptosporidium spp. in pigs was age-specific; piglets were more susceptible to C. suis while pigs were more susceptible to Cryptosporidium pig genotype II. These findings combined with the isolation of the two Cryptosporidium from water suggest that pigs may be a source of zoonotic Cryptosporidium water pollution. Improvements in pig feeding practices, sewage discharge, feces disposal and field worker protection are therefore important to prevent potential public health problems.</p>