Placentas from healthy women living in a cutaneous leishmaniasis endemic region in Mexico harbor Leishmania mexicana parasites: Potential implications for pregnancy and neonatal outcomes

@article{armijos2026placentas,
  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}},
  author = {Rodrigo X. Armijos and Brandon A. Berger and Alejandra González Ayala and Miriam A. Delgado-Hernandez and José Luis Acosta-Patiño and Esmelin Trinidad-Vázquez and Liliana Aline Fernández-Urrutia and Elizabeth Baz-Rojas and Javier Mancilla-Galindo and Candelaria Frías Selván and Juana Ortíz-Avalos and Eva Cristina Avalos-Ortiz and Frida Häberle and Miriam Torres-Vasquez and M. Margaret Weigel and Allison H. Bartlett and Yuriria Paredes and Miroslava Avila-García and Magdalena Aguirre García and Norma Galindo-Sevilla},
  journal = {PLOS Neglected Tropical Diseases},
  year = {2026},
  month = sep,
  doi = {10.1371/journal.pntd.0014367},
  url = {https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014367},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Placentas from healthy women living in a cutaneous leishmaniasis endemic region in Mexico harbor Leishmania mexicana parasites: Potential implications for pregnancy and neonatal outcomes
AU  - Rodrigo X. Armijos
AU  - Brandon A. Berger
AU  - Alejandra González Ayala
AU  - Miriam A. Delgado-Hernandez
AU  - José Luis Acosta-Patiño
AU  - Esmelin Trinidad-Vázquez
AU  - Liliana Aline Fernández-Urrutia
AU  - Elizabeth Baz-Rojas
AU  - Javier Mancilla-Galindo
AU  - Candelaria Frías Selván
AU  - Juana Ortíz-Avalos
AU  - Eva Cristina Avalos-Ortiz
AU  - Frida Häberle
AU  - Miriam Torres-Vasquez
AU  - M. Margaret Weigel
AU  - Allison H. Bartlett
AU  - Yuriria Paredes
AU  - Miroslava Avila-García
AU  - Magdalena Aguirre García
AU  - Norma Galindo-Sevilla
PY  - 2026
DA  - 2026/09/15
JO  - PLOS Neglected Tropical Diseases
DO  - 10.1371/journal.pntd.0014367
UR  - https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014367
AB  - 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.
SN  - 1935-2735
ER  -