{ "abstract": "Background: Women living in leishmaniasis-endemic zones are regularly exposed to the sandfly vector in their environments. While case series and laboratory evidence consistently suggest transplacental transmission of Leishmania parasites with deleterious maternal-fetal effects, this issue has received insufficient attention, particularly in areas where the predominant Leishmania species is mainly associated with cutaneous disease. Methodology/principal findings: We conducted an exploratory cross-sectional study in a highly endemic zone of Tabasco, Mexico, enrolling 53 women with singleton term deliveries between April 2018 and April 2020. Placental PCR was positive in 18 (34%) participants. Buccal swabs were positive in 11 (21.2%) of 52 newborns. Immunofluorescence confirmed intracellular amastigotes within macrophages near the vascular endothelium of PCR-positive placentas, with no surrounding inflammatory infiltration. Sequencing revealed homology to Leishmania mexicana, L. amazonensis, or L. panamensis. Birthweight percentile was modestly lower in the PCR-positive group (predicted mean 53.8% vs. 56.5%, p = 0.76), while small for gestational age showed a non-significant trend toward higher prevalence among PCR-positive cases (prevalence ratio = 2.06, 95% CI: 0.32–13.39, p = 0.45). Conclusions/significance: Subclinical, dynamic transmission of Leishmania parasites typically associated with cutaneous disease was detected in this endemic zone. The presence of L. mexicana in human placentas was confirmed by immunofluorescence and sequencing, without an associated inflammatory response. These findings highlight the potential of CL-associated Leishmania species to reach the placenta and buccal mucosa of newborns, warranting further epidemiological investigation into the consequences of vertical transmission in regions with endemic CL. Author summary: Leishmaniasis is a parasitic infection mainly known for causing skin ulcers (cutaneous leishmaniasis) or severe internal disease (visceral leishmaniasis). While congenital transmission of Leishmania has been documented in visceral disease, the potential for cutaneous species to cross the placenta has received less attention. We studied 53 pregnant women living in a highly endemic region of Tabasco, Mexico, and found that one-third harbored Leishmania DNA in their placentas, while about one-fifth of their newborns showed positive buccal swabs. Importantly, the women showed no clinical signs of cutaneous leishmaniasis, indicating that subclinical infection can still allow parasites to reach the placenta. We confirmed the presence of the parasite in placental tissue using immunofluorescence microscopy and DNA sequencing; the sequences matched Leishmania species associated with cutaneous disease, and species-specific sequencing confirmed Leishmania mexicana. The parasite was found inside immune cells (macrophages), without causing visible inflammation, suggesting the parasite can persist silently in placental tissue. These findings are important for women of reproductive age living in or travelling to cutaneous leishmaniasis-endemic regions, as they and their newborns may be at risk of subclinical exposure to the parasite.", "abstract_shown": true, "affiliations": [ "Global Environmental Health Laboratory, Department of Environmental & Occupational Health, Indiana University-Bloomington School of Public Health, Bloomington, Indiana, United States of America", "Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States of America", "Maestría en Investigación Clínica, Escuela Superior de Medicina, Instituto Politécnico Nacional, Ciudad de México, Mexico", "División Académica de Ciencias de la Salud, Universidad Juárez Autónoma de Tabasco, Villahermosa, Tabasco, Mexico", "Jurisdicción Cunduacán, Secretaría de Salud de Tabasco, Cunduacán, Tabasco, Mexico", "Saint Luke School of Medicine, Alliant International University, Ciudad de México, Mexico", "Institute for Risk Assessment Sciences, Utrecht University, Utrecht, The Netherlands", "Hospital Regional de Cunduacán, Secretaría de Salud de Tabasco, Cunduacán, Tabasco, Mexico", "CETis No. 70, SEP, Villahermosa, Tabasco, Mexico", "Hospital Regional de Alta Especialidad Dr. Gustavo A. Rovirosa Pérez, Villahermosa, Tabasco, Mexico", "Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico", "Section of Infectious Disease, University of Chicago Comer Children’s Hospital, Chicago, Illinois, United States of America", "Departamento de Infectología e Inmunología, Instituto Nacional de Perinatología, Secretaría de Salud, Ciudad de México, Mexico" ], "article_type": "Research Article", "arxiv": null, "author_total": 20, "authors": [ { "affs": [ 0 ], "name": "Rodrigo X. Armijos" }, { "affs": [ 1 ], "name": "Brandon A. Berger" }, { "affs": [ 2 ], "name": "Alejandra González Ayala" }, { "affs": [ 3 ], "name": "Miriam A. Delgado-Hernandez" }, { "affs": [ 4 ], "name": "José Luis Acosta-Patiño" }, { "affs": [ 5 ], "name": "Esmelin Trinidad-Vázquez" }, { "affs": [ 6 ], "name": "Liliana Aline Fernández-Urrutia" }, { "affs": [ 7 ], "name": "Elizabeth Baz-Rojas" }, { "affs": [ 8 ], "name": "Javier Mancilla-Galindo" }, { "affs": [ 9 ], "name": "Candelaria Frías Selván" }, { "affs": [ 10 ], "name": "Juana Ortíz-Avalos" }, { "affs": [ 11 ], "name": "Eva Cristina Avalos-Ortiz" }, { "affs": [ 12 ], "name": "Frida Häberle" }, { "name": "Miriam Torres-Vasquez" }, { "name": "M. Margaret Weigel" }, { "name": "Allison H. Bartlett" }, { "name": "Yuriria Paredes" }, { "name": "Miroslava Avila-García" }, { "name": "Magdalena Aguirre García" }, { "name": "Norma Galindo-Sevilla" } ], "bibtex": "https://research.draconitic.com/paper/4synykcmqd9bf.bib", "cited_by": 0, "doi": "10.1371/journal.pntd.0014367", "fulltext_url": "https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014367", "id": "4synykcmqd9bf", "issns": [ "1935-2735" ], "landing_url": "https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014367", "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", "2739|Research on Leishmaniasis Studies" ], [ "plos", "/Biology and life sciences/Developmental biology/Life cycles/Protozoan life cycles/Amastigotes" ], [ "plos", "/Biology and life sciences/Developmental biology/Neonates" ], [ "plos", "/Biology and life sciences/Microbiology/Protozoology/Protozoan life cycles/Amastigotes" ], [ "plos", "/Biology and life sciences/Molecular biology/Molecular biology techniques/Artificial gene amplification and extension/Polymerase chain reaction" ], [ "plos", "/Biology and life sciences/Organisms/Eukaryota/Protozoans/Parasitic protozoans/Leishmania" ], [ "plos", "/Medicine and health sciences/Medical conditions/Infectious diseases/Zoonoses/Leishmaniasis" ], [ "plos", "/Medicine and health sciences/Medical conditions/Parasitic diseases" ], [ "plos", "/Medicine and health sciences/Medical conditions/Parasitic diseases/Protozoan infections" ], [ "plos", "/Medicine and health sciences/Medical conditions/Parasitic diseases/Protozoan infections/Leishmaniasis" ], [ "plos", "/Medicine and health sciences/Medical conditions/Tropical diseases/Neglected tropical diseases/Leishmaniasis" ], [ "plos", "/Medicine and health sciences/Women's health/Maternal health/Pregnancy" ], [ "plos", "/Medicine and health sciences/Women's health/Obstetrics and gynecology/Pregnancy" ], [ "plos", "/Research and analysis methods/Molecular biology techniques/Artificial gene amplification and extension/Polymerase chain reaction" ] ], "openalex": "W7213333788", "pdf_url": "https://journals.plos.org/plosntds/article/file?id=10.1371/journal.pntd.0014367&type=printable", "pmcid": null, "pmid": null, "published": "2026-09-15", "publisher": "Public Library of Science", "ris": "https://research.draconitic.com/paper/4synykcmqd9bf.ris", "sources": [ { "first_seen": "2026-10-30T12:17:49Z", "native_id": "10.1371/journal.pntd.0014367", "source": "plos", "url": "https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014367" } ], "subjects": [ { "field": "biology", "origin": "plos:developmental biology", "subfield": "developmental-biology" }, { "field": "biology", "origin": "plos:microbiology", "subfield": "microbiology" }, { "field": "medicine", "origin": "plos:women's health", "subfield": "reproductive-child" } ], "title": "Placentas from healthy women living in a cutaneous leishmaniasis endemic region in Mexico harbor Leishmania mexicana parasites: Potential implications for pregnancy and neonatal outcomes", "title_text": "Placentas from healthy women living in a cutaneous leishmaniasis endemic region in Mexico harbor Leishmania mexicana parasites: Potential implications for pregnancy and neonatal outcomes", "type": "peer-reviewed", "updated_at": "2026-10-30T12:17:49Z", "url": "https://research.draconitic.com/paper/4synykcmqd9bf", "venue": "PLOS Neglected Tropical Diseases", "versions": [] }