{ "abstract": "Background: To support Tanzania’s quest for certification free of human yaws, we tested children with skin ulcers for yaws infection living near areas of reported nonhuman primate (NHP) infection with Treponema pallidum subsp. pertenue (TPE). The study also aimed to test children for infection with Haemophilus ducreyi (HD), the most common differential diagnosis for yaws. Methodology/principal findings: A cross-sectional design was used to study primary school children with skin ulcers living near wildlife areas with TPE infected NHPs. Serum and ulcer swab samples were collected from the children. Serum samples were tested for anti-T. pallidum antibodies using treponemal (Particle Agglutination Assay) and non-treponemal (Rapid Plasma Reagin) tests. Ulcer swab samples were tested by quantitative PCR (qPCR) for the presence of TPE and HD bacteria. 612 children were recruited from 56 primary schools between August 2018 and February 2019. The mean age ± SD was 10.3 ± 2.3 and 10.7 ± 2.4 years for girls and boys, respectively. While none of the tested children had treponemal or non-treponemal antibodies, 21 (5.3%, 95% CI = 3.5% - 7.9%) were tested positive for HD by qPCR. Only strains that fall into the HD genotype class I were detected. Conclusions/significance: We show that human yaws infection is likely interrupted in the study areas, although the yaws bacterium is still circulating in NHPs. Due to the potential zoonotic nature of NHP-infecting strains, continued surveillance is needed for yaws and HD infection. Here, we provide the first data on HD associated (non-genital) skin lesions in Tanzanian children. Author summary: Yaws, an infection caused by Treponema pallidum subsp. pertenue (TPE), primarily affects children and was once common in tropical regions. Tanzania previously recorded instances of human yaws, but has not documented any since 1978, making its present status unclear. The situation is further complicated by the natural infection of nonhuman primates (NHPs) in sub-Saharan Africa with the yaws bacterium. Our research examined school-aged children from rural districts who have skin ulcers and live near NHPs known to carry TPE. Using serological and molecular tests, we found no evidence of active or latent human yaws infection, indicating that human-to-human transmission has been interrupted in the surveyed areas. However, 5.3% of 400 tested children had skin ulcers infected with Haemophilus ducreyi (HD), a bacterium that causes yaws-like skin lesions and poses diagnostic challenges for the yaws eradication program. These findings represent the first report of HD-associated non-genital ulcers in Tanzanian children. Although yaws seems to be eliminated in the study area, the continued presence of HD infections and the zoonotic potential of TPE in NHPs highlight the necessity for continuous yaws surveillance, enhanced diagnostic methods, and education in hygiene.", "abstract_shown": true, "affiliations": [ "National Institute for Medical Research, Muhimbili Medical Research Centre, Dar es Salaam, Tanzania", "Institute of International Animal Health/One Health, Friedrich-Loeffler-Institut, Federal Institute for Animal Health, Greifswald, Germany", "Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana", "Kumasi Centre for Collaborative Research in Tropical Medicine, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana", "Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic", "Primate Genetics Laboratory, Deutsches Primatenzentrum GmbH, Leibniz Institute for Primate Research, Goettingen, Germany", "Gene Bank of Primates, Deutsches Primatenzentrum GmbH, Leibniz Institute for Primate Research, Goettingen, Germany", "Faculty of Veterinary Medicine, Justus Liebig University, Giessen, Germany" ], "article_type": "Research Article", "arxiv": null, "author_total": 10, "authors": [ { "affs": [ 0 ], "name": "Clara Clavery Lubinza" }, { "affs": [ 1 ], "name": "Alina Johanna Anton" }, { "affs": [ 2 ], "name": "Simone Lueert" }, { "affs": [ 3 ], "name": "Eugene Adade" }, { "affs": [ 4 ], "name": "Idrissa Shomari Chuma" }, { "affs": [ 5 ], "name": "Augustina Angelina Sylverken" }, { "affs": [ 6 ], "name": "David Šmajs" }, { "affs": [ 7 ], "name": "Sayoki Godfrey Mrinde Mfinanga" }, { "name": "Christian Roos" }, { "name": "Sascha Knauf" } ], "bibtex": "https://research.draconitic.com/paper/d6t7x5sb1g6dz.bib", "cited_by": 0, "doi": "10.1371/journal.pntd.0014567", "fulltext_url": "https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014567", "id": "d6t7x5sb1g6dz", "issns": [ "1935-2735" ], "landing_url": "https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014567", "language": null, "licence": "CC-BY-4.0", "licence_label": "CC BY 4.0", "licence_source": "journal", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "2737|Syphilis Diagnosis and Treatment" ], [ "plos", "/Biology and life sciences/Molecular biology/Molecular biology techniques/Artificial gene amplification and extension/Polymerase chain reaction" ], [ "plos", "/Medicine and health sciences/Clinical medicine/Signs and symptoms/Ulcers" ], [ "plos", "/Medicine and health sciences/Dermatology/Skin diseases/Skin infections" ], [ "plos", "/Medicine and health sciences/Medical conditions/Infectious diseases/Bacterial diseases/Treponematoses/Yaws" ], [ "plos", "/Medicine and health sciences/Medical conditions/Infectious diseases/Skin infections" ], [ "plos", "/Medicine and health sciences/Medical conditions/Skin diseases/Skin infections" ], [ "plos", "/Medicine and health sciences/Medical conditions/Tropical diseases/Neglected tropical diseases/Treponematoses/Yaws" ], [ "plos", "/Medicine and health sciences/Pathology and laboratory medicine/Serology" ], [ "plos", "/People and places/Geographical locations/Africa/Tanzania" ], [ "plos", "/People and places/Population groupings/Age groups/Children" ], [ "plos", "/People and places/Population groupings/Families/Children" ], [ "plos", "/Research and analysis methods/Molecular biology techniques/Artificial gene amplification and extension/Polymerase chain reaction" ], [ "plos", "/Social sciences/Sociology/Education/Schools" ] ], "openalex": "W7213295797", "pdf_url": "https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0014567&type=printable", "pmcid": null, "pmid": null, "published": "2026-09-15", "publisher": "Public Library of Science", "ris": "https://research.draconitic.com/paper/d6t7x5sb1g6dz.ris", "sources": [ { "first_seen": "2026-10-30T12:17:49Z", "native_id": "10.1371/journal.pntd.0014567", "source": "plos", "url": "https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014567" } ], "subjects": [ { "field": "biochemistry", "origin": "plos:molecular biology", "subfield": "molecular-biology" }, { "field": "medicine", "origin": "plos:infectious diseases", "subfield": "infectious-disease" } ], "title": "Absence of human yaws and detection of Haemophilus ducreyi in skin ulcers of school children near wildlife protected areas in Tanzania", "title_text": "Absence of human yaws and detection of Haemophilus ducreyi in skin ulcers of school children near wildlife protected areas in Tanzania", "type": "peer-reviewed", "updated_at": "2026-10-30T12:17:49Z", "url": "https://research.draconitic.com/paper/d6t7x5sb1g6dz", "venue": "PLOS Neglected Tropical Diseases", "versions": [] }