{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T22:39:56Z","timestamp":1783636796331,"version":"3.55.0"},"reference-count":49,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T00:00:00Z","timestamp":1779840000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["TropicalMed"],"abstract":"<jats:p>Prevalence of soil-transmitted helminth (STH) infections in Sri Lanka has declined from 73.3% in 1954 to &lt;1% in 2017, leading to revised deworming policies and discontinuation of routine deworming in three districts, including Anuradhapura, in 2019. As countries approach elimination, this study assessed human intestinal nematode infection (HINI) prevalence in Anuradhapura, a low-endemic setting, using microscopic and molecular methods. From January to November 2023, 967 primary school children were recruited and screened for HINI using direct smears, Kato\u2013Katz, formalin ether concentration, agar plate culture, scotch tape, and qPCR. Combined microscopy and molecular prevalence was 41.2% for STH and 54.1% for HINI. The most prevalent HINI was Enterobius vermicularis (191, 24.5%), followed by Strongyloides stercoralis (120, 19.2%), Ascaris lumbricoides (113, 18.1%), Trichuris trichiura (40, 6.4%), and hookworm (43, 6.9%). Against the composite reference standard, qPCR demonstrated superior diagnostic performance across all species, achieving sensitivities of 86.7% for Ascaris, 85.0% for Trichuris, and 97.7% for hookworm, consistently exceeding those of microscopy-based methods. Correspondingly, qPCR also identified the highest infection prevalences, detecting Ascaris, Trichuris, and hookworm infections in 15.7%, 5.4%, and 6.7% of participants, respectively. All infections were low-intensity as determined by Kato\u2013Katz. Microscopy significantly underestimates STH prevalence. In post-deworming settings, integrated surveillance including molecular diagnostics is essential. The high prevalence of S. stercoralis and E. vermicularis highlights the need for expanded surveillance and targeted interventions to support sustainable control.<\/jats:p>","DOI":"10.3390\/tropicalmed11060147","type":"journal-article","created":{"date-parts":[[2026,5,27]],"date-time":"2026-05-27T11:03:27Z","timestamp":1779879807000},"page":"147","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Residual Human Intestinal Nematode Infections Following Discontinuation of Mass Drug Administration in a Rural South Asian Setting: Implications for Deworming Surveillance"],"prefix":"10.3390","volume":"11","author":[{"given":"Nalini","family":"Jayakody","sequence":"first","affiliation":[{"name":"Department of Parasitology, Faculty of Medicine, Wayamba University of Sri Lanka, Kuliyapitiya 60200, Sri Lanka"},{"name":"Department of Parasitology, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, Saliyapura 50008, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Catherine A.","family":"Gordon","sequence":"additional","affiliation":[{"name":"Infection and Inflammation Program, Applied Tropical and Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane 4006, Queensland, Australia"},{"name":"Faculty of Medicine, The University of Queensland, Brisbane 4072, Queensland, Australia"},{"name":"Center for Tropical Health and Emerging Diseases, QIMR Berghofer Medical Research Institute, Brisbane 4006, Queensland, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anjana","family":"Silva","sequence":"additional","affiliation":[{"name":"Department of Parasitology, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, Saliyapura 50008, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6025-6022","authenticated-orcid":false,"given":"Nuwan","family":"Wickramasinghe","sequence":"additional","affiliation":[{"name":"Department of Community Medicine, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, Saliyapura 50008, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susiji","family":"Wickramasinghe","sequence":"additional","affiliation":[{"name":"Department of Parasitology, Faculty of Medicine, University of Peradeniya, Kandy 20400, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Natasha","family":"Collinson","sequence":"additional","affiliation":[{"name":"Infection and Inflammation Program, Applied Tropical and Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane 4006, Queensland, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7059-6079","authenticated-orcid":false,"given":"Asela","family":"Wijayasekara","sequence":"additional","affiliation":[{"name":"Department of Parasitology, Faculty of Medicine, Wayamba University of Sri Lanka, Kuliyapitiya 60200, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-2945-5088","authenticated-orcid":false,"given":"Chanaka","family":"Karunarathne","sequence":"additional","affiliation":[{"name":"Department of Physiology, Faculty of Medicine, Wayamba University of Sri Lanka, Kuliyapitiya 60200, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nilanthi","family":"de Silva","sequence":"additional","affiliation":[{"name":"Department of Parasitology, Faculty of Medicine, University of Kelaniya, Ragama 11010, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kosala","family":"Weerakoon","sequence":"additional","affiliation":[{"name":"Department of Parasitology, Faculty of Medicine and Allied Sciences, Rajarata University of Sri Lanka, Saliyapura 50008, Sri Lanka"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,27]]},"reference":[{"key":"ref_1","unstructured":"World Health Organization (WHO) (2024, July 26). Soil-Transmitted Helminth Infections. Available online: https:\/\/www.who.int\/news-room\/fact-sheets\/detail\/soil-transmitted-helminth-infections."},{"key":"ref_2","unstructured":"Ryan, K.J., and George, C. (2018). Sherris & Ryan\u2019s Medical Microbiology, McGraw-Hill Education. [8th ed.]."},{"key":"ref_3","unstructured":"Centers for Disease Control and Prevention (CDC) (2024, September 05). About Soil-Transmitted Helminths, Available online: https:\/\/www.cdc.gov\/sth\/about\/index.html."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Strunz, E.C., Addiss, D.G., Stocks, M.E., Ogden, S., Utzinger, J., and Freeman, M.C. (2014). Water, sanitation, hygiene, and soil-transmitted helminth infection: A systematic review and meta-analysis. PLoS Med., 11.","DOI":"10.1371\/journal.pmed.1001620"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Degarege, A., Erko, B., Negash, Y., and Animut, A. (2022). Intestinal Helminth Infection, Anemia, undernutrition and academic performance among school children in northwestern Ethiopia. Microorganisms, 10.","DOI":"10.3390\/microorganisms10071353"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"252","DOI":"10.1016\/S0140-6736(17)31930-X","article-title":"Soil-transmitted helminth infections","volume":"391","author":"Jourdan","year":"2018","journal-title":"Lancet"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"324","DOI":"10.1186\/s13071-020-04197-w","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","journal-title":"Parasites Vectors"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"374","DOI":"10.1186\/s13071-017-2306-2","article-title":"A cross-sectional survey of soil-transmitted helminthiases in two Myanmar villages receiving mass drug administration: Epidemiology of infection with a focus on adults","volume":"10","author":"Dunn","year":"2017","journal-title":"Parasites Vectors"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"550","DOI":"10.4103\/1995-7645.296723","article-title":"Multiplex real-time PCR revealed very high prevalence of soil-transmitted helminth infections among aborigines in Peninsular Malaysia","volume":"13","author":"Othman","year":"2020","journal-title":"Asian Pac. J. Trop. Med."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Mationg, M.L.S., Gordon, C.A., Tallo, V.L., Olveda, R.M., Alday, P.P., Re\u00f1osa, M.D.C., Bieri, F.A., Williams, G.M., Clements, A.C.A., and Steinmann, P. (2017). Status of soil-transmitted helminth infections in schoolchildren in Laguna Province, the Philippines: Determined by parasitological and molecular diagnostic techniques. PLoS Negl. Trop. Dis., 11.","DOI":"10.1371\/journal.pntd.0006022"},{"key":"ref_11","unstructured":"Anchylostomiasis\u2014Ceylon, Administration Reports of the Principal Civil Medical Officer and Inspector General of Hospitals, 1888 (abstracted), Registrar General\u2019s Archives. Available online: https:\/\/noolaham.net\/project\/1330\/132977\/132977.pdf."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1017\/S0025727300056052","article-title":"The hookworm epidemic on the plantations in colonial Sri Lanka","volume":"38","author":"Hewa","year":"1994","journal-title":"Med. Hist."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"e1237","DOI":"10.1016\/S2214-109X(19)30253-0","article-title":"Reassessment of the prevalence of soil-transmitted helminth infections in Sri Lanka to enable a more focused control programme: A cross-sectional national school survey with spatial modelling","volume":"7","author":"Ediriweera","year":"2019","journal-title":"Lancet Glob. Health"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Jayakody, N.K., Silva, A., Wickramasinghe, S., de Silva, N., Siribaddana, S., and Weerakoon, K.G. (2024). Human intestinal nematode infections in Sri Lanka: A scoping review. PLoS Negl. Trop. Dis., 18.","DOI":"10.1371\/journal.pntd.0012689"},{"key":"ref_15","unstructured":"Ministry of Health (2018). Guidelines on De-Worming Children and Pregnant Women Against Soil-Transmitted Helminths in Community Setting: 2019\u20132022."},{"key":"ref_16","unstructured":"World Health Organization (WHO) (2025, November 16). Guideline: Preventive Chemotherapy to Control Soil-Transmitted Helminths Infections in at Risk Population Groups. Geneva. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789241550116."},{"key":"ref_17","unstructured":"(2024, May 12). Sri Lanka\u2014Climatology|Climate Change Knowledge Portal. Available online: https:\/\/climateknowledgeportal.worldbank.org\/country\/sri-lanka\/climate-data-historical."},{"key":"ref_18","unstructured":"Department of Census and Statistics, Sri Lanka (2024, May 12). Household Income and Expenditure 2019, Available online: https:\/\/www.statistics.gov.lk\/IncomeAndExpenditure\/StaticalInformation#gsc.tab=0."},{"key":"ref_19","unstructured":"North Central Province (2024, May 13). Department of Education 2023. Available online: https:\/\/www.edncp.lk\/ht\/index.php."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"121","DOI":"10.4103\/0253-7176.116232","article-title":"How to calculate sample size for different study designs in medical research?","volume":"35","author":"Charan","year":"2013","journal-title":"Indian J. Psychol. Med."},{"key":"ref_21","unstructured":"World Health Organization (2019). Bench Aids for the Diagnosis of Intestinal Parasites, World Health Organization. [2nd ed.]."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"518","DOI":"10.4269\/ajtmh.1991.45.518","article-title":"A modified agar plate method for detection of Strongyloides stercoralis","volume":"45","author":"Koga","year":"1991","journal-title":"Am. J. Trop. Med. Hyg."},{"key":"ref_23","unstructured":"(2025, January 08). HiPurA Stool DNA Purification Kit. Available online: https:\/\/www.himedialabs.com\/us\/mb544-hipura-stool-dna-purification-kit.html."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"338","DOI":"10.4269\/ajtmh.2011.10-0499","article-title":"A pentaplex real-time polymerase chain reaction assay for detection of four species of soil-transmitted helminths","volume":"84","author":"Basuni","year":"2011","journal-title":"Am. J. Trop. Med. Hyg."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Pilotte, N., Papaiakovou, M., Grant, J.R., Bierwert, L.A., Llewellyn, S., McCarthy, J.S., and Williams, S.A. (2016). Improved PCR-based detection of soil transmitted helminth infections using a next-generation sequencing approach to assay design. PLoS Negl. Trop. Dis., 10.","DOI":"10.1371\/journal.pntd.0004578"},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Papaiakovou, M., Pilotte, N., Grant, J.R., Traub, R.J., Llewellyn, S., McCarthy, J.S., Krolewiecki, A.J., Cimino, R., Mejia, R., and Williams, S.A. (2017). A novel, species-specific, real-time PCR assay for the detection of the emerging zoonotic parasite Ancylostoma ceylanicum in human stool. PLoS Negl. Trop. Dis., 11.","DOI":"10.1371\/journal.pntd.0005734"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Llewellyn, S., Inpankaew, T., Nery, S.V., Gray, D.J., Verweij, J.J., Clements, A.C., Gomes, S.J., Traub, R., and McCarthy, J.S. (2016). Application of a Multiplex Quantitative PCR to Assess Prevalence and Intensity of Intestinal Parasite Infections in a Controlled Clinical Trial. PLoS Negl. Trop. Dis., 10.","DOI":"10.1371\/journal.pntd.0004380"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Jayakody, N., Gordon, C.A., Wickramasinghe, N., Silva, A., Wickramasinghe, S., and Weerakoon, K. (2026). Diagnostic accuracy of nucleic acid amplification tests for human intestinal nematode infections: A systematic review and meta-analysis. PLoS Negl. Trop. Dis., 20.","DOI":"10.1371\/journal.pntd.0013974"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"378","DOI":"10.1016\/j.pt.2016.01.006","article-title":"Cell-free DNA as a diagnostic tool for human parasitic infections","volume":"32","author":"Weerakoon","year":"2016","journal-title":"Trends Parasitol."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Assefa, L.M., Crellen, T., Kepha, S., Kihara, J.H., Njenga, S.M., Pullan, R.L., and Brooker, S.J. (2014). Diagnostic accuracy and cost-effectiveness of alternative methods for detection of soil-transmitted helminths in a post-treatment setting in western Kenya. PLoS Negl. Trop. Dis., 8.","DOI":"10.1371\/journal.pntd.0002843"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"333","DOI":"10.2174\/0115733963283507240115112552","article-title":"Pinworm (Enterobius vermicularis) Infestation: An Updated Review","volume":"21","author":"Leung","year":"2025","journal-title":"Curr. Pediatr. Rev."},{"key":"ref_32","unstructured":"Samudrika, R.D., Fernando, W.B.N.T., and Yahathugoda, T.C. (2023, January 20\u201321). Evaluation of the Effectiveness of a Modified Cellophane (Scotch) Tape Method to Diagnose Enterobiasis in a Selected Paediatric Population in Sri Lanka. Proceedings of the International Research Symposium of the Faculty of Allied Health Sciences, Galle, Sri Lanka."},{"key":"ref_33","first-page":"29","article-title":"Patterns of parasites in a paediatric ward in the General Hospital (Teaching) Jaffna","volume":"18","author":"Ramdas","year":"1989","journal-title":"Ceylon J. Child. Health"},{"key":"ref_34","first-page":"23","article-title":"Intestinal parasitic infestations in children living in the underprivileged sector of the Jaffna municipality","volume":"XXI","author":"Nageswaran","year":"1986","journal-title":"Jaffna Med. J."},{"key":"ref_35","first-page":"16","article-title":"Geohelminthic infection in an estate child population in Sri Lanka: Association with hygienic practices and eosinophil counts","volume":"4","author":"Banneheke","year":"2006","journal-title":"Bull. Sri Lanka Coll. Microbiol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"427","DOI":"10.1186\/s13071-024-06508-x","article-title":"Detection of human strongyloidiasis among patients with a high risk of complications attending selected tertiary care hospitals in Colombo, Sri Lanka using molecular and serological diagnostic tools","volume":"17","author":"Weerasekera","year":"2024","journal-title":"Parasites Vectors"},{"key":"ref_37","unstructured":"World Health Organization (WHO) (2026, March 16). WHO Releases Guideline on Public Health Control of Human Strongyloidiasis. Available online: https:\/\/www.who.int\/news\/item\/02-08-2024-who-releases-guideline-on-public-health-control-of-human-strongyloidiasis."},{"key":"ref_38","unstructured":"World Health Organization (WHO) (2024). WHO Guideline on Preventive Chemotherapy for Public Health Control of Strongyloidiasis, World Health Organization. Available online: https:\/\/www.who.int\/publications\/i\/item\/9789240094024."},{"key":"ref_39","doi-asserted-by":"crossref","unstructured":"de Ree, V., Nath, T.C., Barua, P., Harbecke, D., Lee, D., R\u00f6delsperger, C., and Streit, A. (2024). Genomic analysis of Strongyloides stercoralis and Strongyloides fuelleborni in Bangladesh. PLoS Negl. Trop. Dis., 18.","DOI":"10.1101\/2024.05.16.24307305"},{"key":"ref_40","unstructured":"Hector Kobbekaduwa Agrarian Research and Training Institute (2026, March 23). Research Report, Available online: https:\/\/www.harti.gov.lk\/index.php\/en\/publication\/research-report."},{"key":"ref_41","first-page":"1162","article-title":"Ancylostoma ceylanicum First ever Case Detected in Sri Lanka","volume":"7","author":"Mallawarachchi","year":"2020","journal-title":"Austin J. Clin. Case Rep."},{"key":"ref_42","first-page":"86","article-title":"Laboratory diagnosis of soil transmitted helminthiasis","volume":"7","author":"Khurana","year":"2017","journal-title":"Trop. Parasitol."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1145","DOI":"10.4269\/ajtmh.23-0821","article-title":"Estimating Prevalence and Infection Intensity of Soil-Transmitted Helminths Using Quantitative Polymerase Chain Reaction and Kato-Katz in School-Age Children in Angola","volume":"110","author":"Soultani","year":"2024","journal-title":"Am. J. Trop. Med. Hyg."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1033","DOI":"10.4269\/ajtmh.18-0356","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","journal-title":"Am. J. Trop. Med. Hyg."},{"key":"ref_45","unstructured":"World Health Organization (WHO) (2020). Ending the Neglect to Attain the Sustainable Development Goals: A Road Map for Negl. Tropical Diseases 2021\u20132030, WHO."},{"key":"ref_46","unstructured":"World Health Organization (2023). Schistosomiasis and soil-transmitted helminthiases: Progress report, 2023. Wkly. Epidemiol. Rec., 99, 707\u2013717. Available online: https:\/\/www.who.int\/publications\/i\/item\/WHO-WER9948-707-717."},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Buonfrate, D., Bisanzio, D., Giorli, G., Odermatt, P., F\u00fcrst, T., Greenaway, C., French, M., Reithinger, R., Gobbi, F., and Montresor, A. (2020). The Global Prevalence of Strongyloides stercoralis Infection. Pathogens, 9.","DOI":"10.3390\/pathogens9060468"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1186\/s40249-023-01138-4","article-title":"Prevalence of Strongyloides in Southeast Asia: A systematic review and meta-analysis with implications for public health and sustainable control strategies","volume":"12","author":"Chan","year":"2023","journal-title":"Infect. Dis. Poverty"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"273","DOI":"10.1186\/s13071-019-3532-6","article-title":"The role of water, sanitation and hygiene interventions in reducing soil-transmitted helminths: Interpreting the evidence and identifying next steps","volume":"12","author":"Pickering","year":"2019","journal-title":"Parasites Vectors"}],"container-title":["Tropical Medicine and Infectious Disease"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2414-6366\/11\/6\/147\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,29]],"date-time":"2026-05-29T04:15:21Z","timestamp":1780028121000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2414-6366\/11\/6\/147"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,5,27]]},"references-count":49,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,6]]}},"alternative-id":["tropicalmed11060147"],"URL":"https:\/\/doi.org\/10.3390\/tropicalmed11060147","relation":{},"ISSN":["2414-6366"],"issn-type":[{"value":"2414-6366","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5,27]]}}}