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Prevalence and genotypic characterization of Giardia duodenalis isolates from asymptomatic school-going children in Lusaka, Zambia.

ABSTRACT: Giardia duodenalis is one of the most common causes of diarrhea in humans with about 250-300 million cases per year. It is considered to be a species complex comprising of eight genetic assemblages (A to H), with assemblages A and B being the major causes of human infections. In this study we carried out genotypic characterization of G. duodenalis isolates detected in asymptomatic school-going children aged 3-16?years. Between May and September 2017, a total of 329 fecal samples were collected from school-going children from Chawama compound of Lusaka City and were screened for Giardia by microscopic examination. All microscopically positive fecal samples were analyzed by semi-nested polymerase chain reaction (PCR) targeting the glutamate dehydrogenase (gdh) gene. Genotyping of amplified PCR products was conducted by restriction fragment length polymorphism (RFLP) and DNA sequence analysis. Microscopically, Giardia was found in 10% (33/329) of fecal samples. The PCR-RFLP analysis of the gdh gene revealed assemblages A and B in 27.3% (9/33) and 72.7% (24/33), respectively. Furthermore, analysis with restriction enzymes identified sub-assemblages AII (27.3%, 9/33), BIII (12.1%, 4/33), BIV (51.5%, 17/33) and mixed infections of BIII and BIV (9.1%, 3/33). Phylogenetic analysis showed the clustering of 27.6% (8/29) and 72.4% (21/29) of Zambian Giardia gdh gene sequences into assemblages A and B, respectively. This study has revealed the presence of both assemblage A and B and that spread of G. duodenalis in school-going children appears to be mostly through anthroponotic transmission. To our knowledge, this is the first report of genotypic characterization of G. duodenalis identified in Zambia.

SUBMITTER: Tembo SJ

PROVIDER: S-EPMC7125351 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature

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Prevalence and genotypic characterization of Giardia duodenalis isolates from asymptomatic school-going children in Lusaka, Zambia.

Tembo Shadreck J SJ Mutengo Mable M MM Sitali Lungowe L Changula Katendi K Takada Ayato A Mweene Aaron S AS Simulundu Edgar E Chitanga Simbarashe S

Food and waterborne parasitology 20200221

Giardia duodenalis is one of the most common causes of diarrhea in humans with about 250-300 million cases per year. It is considered to be a species complex comprising of eight genetic assemblages (A to H), with assemblages A and B being the major causes of human infections. In this study we carried out genotypic characterization of G. duodenalis isolates detected in asymptomatic school-going children aged 3-16 years. Between May and September 2017, a total of 329 fecal samples we ...[more]

PMID: 32258446

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Project description:BACKGROUND:Human infections by the gastrointestinal helminth Strongyloides stercoralis and the enteric protozoans Giardia duodenalis, Cryptosporidium spp. and Blastocystis spp. are not formally included in the list of 20 neglected tropical diseases prioritised by the World Health Organization. Although largely underdiagnosed and considered of lower public health relevance, these infections have been increasingly demonstrated to cause significant morbidity and even mortality globally, particularly among children living in resource-poor settings. METHODS:In this cross-sectional survey the prevalence, frequency and molecular diversity of S. stercoralis, G. duodenalis, Cryptosporidium spp. and Blastocystis spp. were investigated in a school children population in the province of Benguela (Angola). A total of 351 stool samples were collected during January to June 2015. The presence of S. stercoralis and G. duodenalis was confirmed by qPCR methods. Giardia duodenalis assemblages and sub-assemblages were determined by multilocus sequence-based genotyping of the glutamate dehydrogenase and ?-giardin genes of the parasite. Detection and identification of Cryptosporidium and Blastocystis species and subtypes was carried out by amplification and sequencing of a partial fragment of the small-subunit ribosomal RNA gene of both protozoan. Analyses of risk factors potentially associated with the transmission of these pathogens were also conducted. RESULTS:Prevalences of S. stercoralis, G. duodenalis, Cryptosporidium spp., and Blastocystis spp. were estimated at 21.4% (95% CI: 17.1-25.7%), 37.9% (95% CI: 32.8-43.0%), 2.9% (95% CI: 1.1-4.5%) and 25.6% (95% CI: 21.18-30.2%), respectively. Overall, 64.1% (225/351) of the children were infected by at least one of the pathogens investigated. Sequence analyses of the 28 G. duodenalis isolates that were successfully genotyped allowed the identification of sub-assemblages AI (14.3%), AII (14.3%), BIII (7.1%) and BIV (25.0%). Discordant typing results AII/AIII and BIII/BIV were identified in 7.1% and 14.3% of the isolates, respectively. A total of five additional isolates (17.9%) were identified as assemblage B. Three Cryptosporidium species including C. hominis (70%), C. parvum (20%) and C. canis (10%) were found circulating in the children population under study. A total of 75 Blastocystis isolates were assigned to the subtypes ST1 (30.7%), ST2 (30.7%), ST3 (36.0%), ST5 (1.3%) and ST7 (1.3%), respectively. Children younger than seven years of age had significantly higher risk of infections by protozoan enteropathogens (PRR: 1.35, P?<?0.01), whereas being underweight seemed to have a protective effect against these infections (PRR: 0.74, P?=?0.005). CONCLUSIONS:The burden of disease attributable to human strongyloidiasis, giardiosis, cryptosporidiosis and blastocystosis in Angola is considerably higher than initially estimated in previous surveys. Surveillance and control of these infections should be jointly tackled with formally considered neglected tropical diseases in order to maximize effort and available resources. Our data also demonstrate the added value of using molecular diagnostic methods in high transmission areas.

Project description:BACKGROUND:Cryptosporidium spp., Giardia duodenalis and Enterocytozoon bieneusi are common enteric pathogens in humans and animals. Data on the transmission of these pathogens are scarce from Guangdong, China, which has a subtropical monsoon climate and is the epicenter for many emerging infectious diseases. This study was conducted to better understand the prevalence and identity of the three pathogens in pre-weaned dairy calves in Guangdong. METHODS:The occurrence and genetic identity of three pathogens were analyzed by polymerase chain reaction. PCR-positive products were sequenced to determine the species and genotypes. A Chi-square test was used to compare the prevalence of pathogens among sampling dates, age groups, or clinical signs. RESULTS:The detection rates of Cryptosporidium spp., G. duodenalis and E. bieneusi were 24.0% (93/388), 74.2% (288/388) and 15.7% (61/388), respectively. Three Cryptosporidium species were detected, including C. bovis (n = 73), C. parvum (n = 12) and C. ryanae (n = 7); one animal had concurrence of C. bovis and C. parvum. C. parvum was the dominant species during the first two weeks of life, whereas C. bovis and C. ryanae were mostly seen at 3-9 weeks of age. Sequence analysis identified the C. parvum as subtype IIdA19G1. Assemblage E (n = 282), assemblage A (n = 1), and concurrence of A and E (n = 5) were identified among G. duodenalis-positive animals using multilocus genotyping (MLG). Altogether, 15, 10 and 17 subtypes of assemblage E were observed at the bg, gdh and tpi loci, respectively, forming 49 assemblage E MLGs. The highest detection rate of G. duodenalis was found in winter. Sequence analysis identified genotypes J (n = 57), D (n = 3) and one concurrence of J and D among E. bieneusi-positive animals. The detection rate of E. bieneusi was significantly higher in spring (38.0%; 41/108) than in summer (7.2%; 8/111) and winter (7.1%; 12/169). CONCLUSIONS:These results indicate a common occurrence of C. parvum subtype IIdA19G1, G. duodenalis assemblage E, and E. bieneusi genotype J in pre-weaned dairy calves in Guangdong. More studies are needed to understand the unique genetic characteristics and zoonotic potential of the three enteric pathogens in the province.

Dataset Information

Prevalence and genotypic characterization of Giardia duodenalis isolates from asymptomatic school-going children in Lusaka, Zambia.

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Prevalence and genotypic characterization of <i>Giardia duodenalis</i> isolates from asymptomatic school-going children in Lusaka, Zambia.

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