Absence of human yaws and detection of Haemophilus ducreyi in skin ulcers of school children near wildlife protected areas in Tanzania
8 affiliations
- 1National Institute for Medical Research, Muhimbili Medical Research Centre, Dar es Salaam, Tanzania
- 2Institute of International Animal Health/One Health, Friedrich-Loeffler-Institut, Federal Institute for Animal Health, Greifswald, Germany
- 3Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
- 4Kumasi Centre for Collaborative Research in Tropical Medicine, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
- 5Department of Biology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
- 6Primate Genetics Laboratory, Deutsches Primatenzentrum GmbH, Leibniz Institute for Primate Research, Goettingen, Germany
- 7Gene Bank of Primates, Deutsches Primatenzentrum GmbH, Leibniz Institute for Primate Research, Goettingen, Germany
- 8Faculty of Veterinary Medicine, Justus Liebig University, Giessen, Germany
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.
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BibTeX
@article{lubinza2026absence,
title = {{Absence of human yaws and detection of Haemophilus ducreyi in skin ulcers of school children near wildlife protected areas in Tanzania}},
author = {Clara Clavery Lubinza and Alina Johanna Anton and Simone Lueert and Eugene Adade and Idrissa Shomari Chuma and Augustina Angelina Sylverken and David Šmajs and Sayoki Godfrey Mrinde Mfinanga and Christian Roos and Sascha Knauf},
journal = {PLOS Neglected Tropical Diseases},
year = {2026},
month = sep,
doi = {10.1371/journal.pntd.0014567},
url = {https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014567},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Absence of human yaws and detection of Haemophilus ducreyi in skin ulcers of school children near wildlife protected areas in Tanzania
AU - Clara Clavery Lubinza
AU - Alina Johanna Anton
AU - Simone Lueert
AU - Eugene Adade
AU - Idrissa Shomari Chuma
AU - Augustina Angelina Sylverken
AU - David Šmajs
AU - Sayoki Godfrey Mrinde Mfinanga
AU - Christian Roos
AU - Sascha Knauf
PY - 2026
DA - 2026/09/15
JO - PLOS Neglected Tropical Diseases
DO - 10.1371/journal.pntd.0014567
UR - https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014567
AB - 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.
SN - 1935-2735
ER -