{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T06:49:45Z","timestamp":1791442185764,"version":"4.3.3"},"reference-count":46,"publisher":"American Society of Tropical Medicine and Hygiene","issue":"6","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2024,6,5]]},"abstract":"<jats:title>ABSTRACT.<\/jats:title>\n<jats:p>Quantitative polymerase chain reaction (qPCR) is gaining recognition in soil-transmitted helminth (STH) diagnostics, especially for <jats:italic>Strongyloides stercoralis<\/jats:italic> and differentiating hookworm species. However, sample preservation and DNA extraction may influence qPCR performance. We estimated STH prevalence and infection intensity by using qPCR in schoolchildren from Huambo, Uige, and Zaire, Angola, and compared its performance with that of the Kato-Katz technique (here termed Kato-Katz). Stool samples from 3,063 children (219 schools) were preserved in 96% ethanol and analyzed by qPCR, of which 2,974 children (215 schools) had corresponding Kato-Katz results. Cluster-adjusted prevalence and infection intensity estimates were calculated by qPCR and Kato-Katz, with cycle threshold values converted to eggs per gram for qPCR. Cohen\u2019s kappa statistic evaluated agreement between qPCR and Kato-Katz. DNA extraction and qPCR were repeated on 191 (of 278) samples that were initially qPCR negative but Kato-Katz positive, of which 112 (58.6%) became positive. Similar prevalence for <jats:italic>Ascaris lumbricoides<\/jats:italic> (37.5% versus 34.6%) and <jats:italic>Trichuris trichiura<\/jats:italic> (6.5% versus 6.1%) were found by qPCR and Kato-Katz, respectively, while qPCR detected a higher hookworm prevalence (11.9% versus 2.9%). The prevalence of moderate- or high-intensity infections was higher by Kato-Katz than by qPCR. Agreement between qPCR and Kato-Katz was very good for <jats:italic>A. lumbricoides<\/jats:italic>, moderate for <jats:italic>T. trichiura<\/jats:italic>, and fair for hookworm. <jats:italic>Strongyloides stercoralis<\/jats:italic> prevalence was 4.7% (municipality range, 0\u201314.3%), and no <jats:italic>Ancylostoma ceylanicum<\/jats:italic> was detected by qPCR. Despite suboptimal performance, presumably due to fixative choice, qPCR was fundamental in detecting <jats:italic>S. stercoralis<\/jats:italic> and excluding zoonotic <jats:italic>A. ceylanicum<\/jats:italic>. Further evaluations on sample fixatives and DNA extraction methods are needed to optimize and standardize the performance of qPCR.<\/jats:p>","DOI":"10.4269\/ajtmh.23-0821","type":"journal-article","created":{"date-parts":[[2024,4,30]],"date-time":"2024-04-30T15:32:35Z","timestamp":1714491155000},"page":"1145-1151","source":"Crossref","is-referenced-by-count":6,"title":["Estimating Prevalence and Infection Intensity of Soil-Transmitted Helminths Using Quantitative Polymerase Chain Reaction and Kato-Katz in School-Age Children in Angola"],"prefix":"10.4269","volume":"110","author":[{"given":"Muzhgan","family":"Soultani","sequence":"first","affiliation":[{"name":"School of Population Health, University of New South Wales, Sydney, Australia;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adam W.","family":"Bartlett","sequence":"additional","affiliation":[{"name":"Kirby Institute, University of New South Wales, Sydney, Australia;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elsa P.","family":"Mendes","sequence":"additional","affiliation":[{"name":"National Directorate of Public Health, Ministry of Health, Luanda, Angola;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sze Fui","family":"Hii","sequence":"additional","affiliation":[{"name":"Faculty of Science, University of Melbourne, Parkville, Australia;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rebecca","family":"Traub","sequence":"additional","affiliation":[{"name":"Faculty of Science, University of Melbourne, Parkville, Australia;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marta S.","family":"Palmeirim","sequence":"additional","affiliation":[{"name":"Swiss Tropical and Public Health Institute, Allschwil, Switzerland;"},{"name":"University of Basel, Basel, Switzerland;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luis M. M.","family":"Lufunda","sequence":"additional","affiliation":[{"name":"The MENTOR Initiative, Huambo, Angola"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vito","family":"Colella","sequence":"additional","affiliation":[{"name":"Faculty of Science, University of Melbourne, Parkville, Australia;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sergio","family":"Lopes","sequence":"additional","affiliation":[{"name":"The MENTOR Initiative, Huambo, Angola"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susana","family":"Vaz Nery","sequence":"additional","affiliation":[{"name":"Kirby Institute, University of New South Wales, Sydney, Australia;"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"2795","reference":[{"key":"b1","year":"2011"},{"key":"b2","year":"2021"},{"key":"b3","series-title":"Lancet","first-page":"1260","article-title":"Global, regional, and national disability-adjusted life-years (DALYs) for 333 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990\u20132016: A systematic analysis for the Global Burden of Disease Study 2016","volume":"390","year":"2017"},{"key":"b4","series-title":"Pediatr Infect Dis J","first-page":"e28","article-title":"Etiology of diarrhea in children younger than 5 years attending the Bengo General Hospital in Angola","volume":"35","author":"Gasparinho","year":"2016"},{"key":"b5","series-title":"PLoS One","first-page":"e0137327","article-title":"Infection by intestinal parasites, stunting and anemia in school-aged children from southern Angola","volume":"10","author":"Oliveira","year":"2015"},{"key":"b6","series-title":"PLoS One","first-page":"e33189","article-title":"Epidemiology of malaria, schistosomiasis, geohelminths, anemia and malnutrition in the context of a demographic surveillance system in northern Angola","volume":"7","author":"Sousa-Figueiredo","year":"2012"},{"key":"b7","year":"2020"},{"key":"b8","series-title":"PLoS Negl Trop Dis","first-page":"e2288","article-title":"Strongyloides stercoralis: Global Distribution and Risk Factors","volume":"7","author":"Schar","year":"2013"},{"key":"b9","series-title":"Int J Parasitol","first-page":"1233","article-title":"Zoonotic hookworms of dogs and cats \u2013 lessons from the past to inform current knowledge and future directions of research","volume":"51","author":"Traub","year":"2021"},{"key":"b10","series-title":"Lancet Reg Health West Pac","first-page":"100258","article-title":"Risk profiling and efficacy of albendazole against the hookworms Necator americanus and Ancylostoma ceylanicum in Cambodia to support control programs in Southeast Asia and the Western Pacific","volume":"16","author":"Colella","year":"2021"},{"key":"b11","series-title":"Parasitology","first-page":"274","article-title":"Strongyloides spp. infections of veterinary importance","volume":"144","author":"Thamsborg","year":"2017"},{"key":"b12","series-title":"Am J Trop Med Hyg","first-page":"535","article-title":"Diagnostic accuracy of Kato-Katz, FLOTAC, Baermann, and PCR methods for the detection of light-intensity hookworm and Strongyloides stercoralis infections in Tanzania","volume":"90","author":"Knopp","year":"2014"},{"key":"b13","series-title":"Int J Parasitol","first-page":"765","article-title":"Sensitivity of diagnostic tests for human soil-transmitted helminth infections: A meta-analysis in the absence of a true gold standard","volume":"44","author":"Nikolay","year":"2014"},{"key":"b14","series-title":"PLoS Negl Trop Dis","first-page":"e0009395","article-title":"Comparison of the egg recovery rates and limit of detection for soil-transmitted helminths using the Kato-Katz thick smear, faecal flotation and quantitative real-time PCR in human stool","volume":"15","author":"Zendejas-Heredia","year":"2021"},{"key":"b15","series-title":"Acta Trop","first-page":"210","article-title":"Real-time PCR for detection of Strongyloides stercoralis in human stool samples from C\u00f4te d\u2019Ivoire: Diagnostic accuracy, inter-laboratory comparison and patterns of hookworm co-infection","volume":"150","author":"Becker","year":"2015"},{"key":"b16","series-title":"PLoS Negl Trop Dis","first-page":"e0005752","article-title":"Different but overlapping populations of Strongyloides stercoralis in dogs and humans\u2014Dogs as a possible source for zoonotic strongyloidiasis","volume":"11","author":"Jaleta","year":"2017"},{"key":"b17","series-title":"Trans R Soc Trop Med Hyg","first-page":"342","article-title":"Molecular diagnosis of Strongyloides stercoralis in faecal samples using real-time PCR","volume":"103","author":"Verweij","year":"2009"},{"key":"b18","series-title":"J Parasitol","first-page":"277","article-title":"Evaluation of three methods for laboratory diagnosis of Strongyloides stercoralis infection","volume":"79","author":"de Kaminsky","year":"1993"},{"key":"b19","series-title":"Am J Trop Med Hyg","first-page":"1201","article-title":"Comparison between quantitative polymerase chain reaction and sodium nitrate flotation microscopy in diagnosing soil-transmitted helminth infections","volume":"105","author":"Bartlett","year":"2021"},{"key":"b20","series-title":"Am J Trop Med Hyg","first-page":"1033","article-title":"Quantitative polymerase chain reaction for diagnosis of soil-transmitted helminth infections: A comparison with a flotation-based technique and an investigation of variability in DNA detection","volume":"99","author":"Clarke","year":"2018"},{"key":"b21","series-title":"PLoS Negl Trop Dis","first-page":"e0010350","article-title":"Using quantitative PCR to identify opportunities to strengthen soil-transmitted helminth control in Solomon Islands: A cross-sectional epidemiological survey","volume":"16","author":"Le","year":"2022"},{"key":"b22","series-title":"Acta Trop","first-page":"89","article-title":"Evaluation of real-time PCR for Strongyloides stercoralis and hookworm as diagnostic tool in asymptomatic schoolchildren in Cambodia","volume":"126","author":"Sch\u00e4r","year":"2013"},{"key":"b23","series-title":"PLoS Negl Trop Dis","first-page":"e0009032","article-title":"Diagnosis of soil-transmitted helminths using Kato-Katz: What is the influence of stirring, storage time and storage temperature on stool sample egg counts?","volume":"15","author":"Bosch","year":"2021"},{"key":"b24","series-title":"PLoS Negl Trop Dis","first-page":"e0007778","article-title":"Comparison of four DNA extraction and three preservation protocols for the molecular detection and quantification of soil-transmitted helminths in stool","volume":"13","author":"Ayana","year":"2019"},{"key":"b25","series-title":"Am J Trop Med Hyg","first-page":"335","article-title":"A pilot comparison of fixatives for hookworm real-time polymerase chain reaction","volume":"108","author":"Bradbury","year":"2023"},{"key":"b26","series-title":"PLoS Negl Trop Dis","first-page":"e0006130","article-title":"A comparative analysis of preservation techniques for the optimal molecular detection of hookworm DNA in a human fecal specimen","volume":"12","author":"Papaiakovou","year":"2018"},{"key":"b27","series-title":"Infect Dis Poverty","first-page":"73","article-title":"Burden and factors associated with schistosomiasis and soil-transmitted helminth infections among school-age children in Huambo, Uige and Zaire provinces, Angola","volume":"11","author":"Bartlett","year":"2022"},{"key":"b28","series-title":"PLoS Negl Trop Dis","first-page":"e0010849","article-title":"School-based preventive chemotherapy program for schistosomiasis and soil-transmitted helminth control in Angola: 6-year impact assessment","volume":"17","author":"Bartlett","year":"2023"},{"key":"b29","author":"Dean","year":"2013"},{"key":"b30","series-title":"Parasit Vectors","first-page":"67","article-title":"Prevalence and molecular characterization of Strongyloides stercoralis, Giardia duodenalis, Cryptosporidium spp., and Blastocystis spp. isolates in school children in Cubal, Western Angola","volume":"11","author":"Dacal","year":"2018"},{"key":"b31","series-title":"Am J Trop Med Hyg","first-page":"1226","article-title":"Prevalence of Strongyloides stercoralis and other intestinal parasite infections in school children in a rural area of Angola: A cross-sectional study","volume":"97","author":"de Alegria","year":"2017"},{"key":"b32","series-title":"J Helminthol","first-page":"313","article-title":"Molecular identification of zoonotic hookworm species in dog faeces from Tanzania","volume":"93","author":"Merino-Tejedor","year":"2019"},{"key":"b33","series-title":"J S Afr Vet Assoc","first-page":"139","article-title":"A survey of helminths in domestic cats in the Pretoria area of Transvaal, Republic of South Africa. Part 1: The prevalence and comparison of burdens of helminths in adult and juvenile cats","volume":"60","author":"Baker","year":"1989"},{"key":"b34","series-title":"J Helminthol","first-page":"e39","article-title":"Molecular identification of hookworm isolates from stray dogs, humans and selected wildlife from South Africa","volume":"94","author":"Ngcamphalala","year":"2019"},{"key":"b35","series-title":"Emerg Infect Dis","first-page":"976","article-title":"High prevalence of Ancylostoma ceylanicum hookworm infections in humans, Cambodia, 2012","volume":"20","author":"Inpankaew","year":"2014"},{"key":"b36","series-title":"Emerg Infect Dis","first-page":"1867","article-title":"Zoonotic Ancylostoma ceylanicum hookworm infections, Ecuador","volume":"28","author":"Sears","year":"2022"},{"key":"b37","series-title":"Emerg Infect Dis","first-page":"1870","article-title":"Ancylostoma ceylanicum hookworms in dogs, Grenada, West Indies","volume":"28","author":"Zendejas-Heredia","year":"2022"},{"key":"b38","series-title":"BMC Microbiol","first-page":"298","article-title":"Comparison of real-time PCR and the Kato-Katz method for the diagnosis of soil-transmitted helminthiasis and assessment of cure in a randomized controlled trial","volume":"20","author":"Barda","year":"2020"},{"key":"b39","series-title":"PLoS Negl Trop Dis","first-page":"e0008087","article-title":"Comparison of multi-parallel qPCR and double-slide Kato-Katz for detection of soil-transmitted helminth infection among children in rural Bangladesh","volume":"14","author":"Benjamin-Chung","year":"2020"},{"key":"b40","series-title":"PLoS Negl Trop Dis","first-page":"e3313","article-title":"Simple fecal flotation is a superior alternative to guadruple Kato Katz smear examination for the detection of hookworm eggs in human stool","volume":"8","author":"Inpankaew","year":"2014"},{"key":"b41","series-title":"Parasit Vectors","first-page":"324","article-title":"The increased sensitivity of qPCR in comparison to Kato-Katz is required for the accurate assessment of the prevalence of soil-transmitted helminth infection in settings that have received multiple rounds of mass drug administration","volume":"13","author":"Dunn","year":"2020"},{"key":"b42","series-title":"PLoS Negl Trop Dis","first-page":"e0007446","article-title":"Diagnostic performance of a single and duplicate Kato-Katz, Mini-FLOTAC, FECPAKG2 and qPCR for the detection and quantification of soil-transmitted helminths in three endemic countries","volume":"13","author":"Cools","year":"2019"},{"key":"b43","series-title":"Parasit Vectors","first-page":"517","article-title":"Performance of the Kato-Katz method and real time polymerase chain reaction for the diagnosis of soil-transmitted helminthiasis in the framework of a randomised controlled trial: Treatment efficacy and day-to-day variation","volume":"13","author":"Keller","year":"2020"},{"key":"b44","series-title":"Parasit Vectors","first-page":"38","article-title":"Multi-parallel qPCR provides increased sensitivity and diagnostic breadth for gastrointestinal parasites of humans: Field-based inferences on the impact of mass deworming","volume":"9","author":"Easton","year":"2016"},{"key":"b45","series-title":"Emerg Infect Dis","first-page":"1551","article-title":"Capillaria ova and diagnosis of Trichuris trichiura infection in humans by Kato-Katz smear, Liberia","volume":"24","author":"Fischer","year":"2018"},{"key":"b46","series-title":"Trans R Soc Trop Med Hyg","first-page":"617","article-title":"Copro-molecular identification of infections with hookworm eggs in rural Lao PDR","volume":"104","author":"Sato","year":"2010"}],"container-title":["The American Journal of Tropical Medicine and Hygiene"],"original-title":[],"link":[{"URL":"https:\/\/www.ajtmh.org\/view\/journals\/tpmd\/110\/6\/article-p1145.xml","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.ajtmh.org\/downloadpdf\/journals\/tpmd\/110\/6\/article-p1145.xml","content-type":"text\/html","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/www.ajtmh.org\/downloadpdf\/journals\/tpmd\/110\/6\/article-p1145.xml","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2024,6,5]],"date-time":"2024-06-05T13:00:27Z","timestamp":1717592427000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ajtmh.org\/view\/journals\/tpmd\/110\/6\/article-p1145.xml"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,6,5]]},"references-count":46,"journal-issue":{"issue":"6"},"URL":"https:\/\/doi.org\/10.4269\/ajtmh.23-0821","relation":{},"ISSN":["0002-9637","1476-1645"],"issn-type":[{"value":"0002-9637","type":"print"},{"value":"1476-1645","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,6,5]]}}}