One Health investigation of a human visceral leishmaniasis case in western Portugal
Abstract
Problem: Visceral leishmaniasis (VL) is a rare but potentially fatal zoonosis endemic in southern Europe. It is transmitted by phlebotomine sand flies, with dogs as primary reservoir. Although human VL is a notifiable disease in Portugal, canine VL is not, which limits baseline surveillance.
Description of the problem: In July 2024 a middle-age male outdoor worker presented at a clinic with 10 weeks of fever, weight loss, splenomegaly and hepatomegaly. He was referred to urgent care and subsequently hospitalized and diagnosed with VL. Following notification of the case, the Public Health Unit of West Local Health Unit in Portugal initiated a multidisciplinary epidemiological investigation which covered the period between November 2023 and August 2024. It followed a One Health approach and included patient interview, occupational and environmental field assessment, veterinary inquiry, entomological trapping and laboratory confirmation of the human case at the National Reference Laboratory.
Results: The case was laboratory-confirmed. Appropriate treatment resulted in clinical improvement. Probable site of infection was the patient’s rural residential area, characterized by free-roaming dogs and nearby livestock farming. Sand fly traps (REVIVE program) yielded 13 phlebotomine sand flies, all of which tested negative for Leishmania. A local veterinary clinic reported a perceived increase in canine VL cases. No secondary human cases were identified. Risk was assessed as low (ECDC/UKHSA frameworks).
Lessons: Multi-agency One Health coordination enabled a comprehensive and proportionate response. The absence of mandatory canine VL notification is a surveillance gap shared across Southern Europe, although its endemic state might partly explain this. Diagnostic delay is common in low-incidence diseases but highlights the need for improved clinician awareness in endemic-adjacent settings. Existing REVIVE infrastructure can be rapidly activated for entomological investigation.
Key messages: • A structured One Health investigation of the first confirmed human visceral leishmaniasis case in the West region of Portugal since 2020 showed low community risk but critical surveillance gaps.
• Integrating human, animal, and entomological data into a single response enables proportionate risk assessment for vector-borne diseases in low-incidence settings.
Related
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- Geostatistical modelling of the effect of vegetation on canine visceral leishmaniasis in Camaçari, Bahia State, Northeastern Brazil using remote-sensed data
- Biodiversity, entomological surveillance, and xenomonitoring of sand flies in the Western Ghats, Keralam: an emerging focus of leishmaniasis in India
- Effects of centrifugation-based therapeutic plasma exchange on coagulation parameters in dogs with canine visceral leishmaniasis.
BibTeX
@article{neves2026health,
title = {{One Health investigation of a human visceral leishmaniasis case in western Portugal}},
author = {D Neves and L Pedrosa and E Soares dos Santos and A Vicente and L Moreira and MJ Gargaté and A Vilares and T Reis and F Amaro and N Rodrigues},
journal = {The European Journal of Public Health},
year = {2026},
month = oct,
doi = {10.1093/eurpub/ckag169.1601},
url = {https://doi.org/10.1093/eurpub/ckag169.1601},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - One Health investigation of a human visceral leishmaniasis case in western Portugal
AU - D Neves
AU - L Pedrosa
AU - E Soares dos Santos
AU - A Vicente
AU - L Moreira
AU - MJ Gargaté
AU - A Vilares
AU - T Reis
AU - F Amaro
AU - N Rodrigues
PY - 2026
DA - 2026/10/01
JO - The European Journal of Public Health
DO - 10.1093/eurpub/ckag169.1601
UR - https://doi.org/10.1093/eurpub/ckag169.1601
AB - Problem: Visceral leishmaniasis (VL) is a rare but potentially fatal zoonosis endemic in southern Europe. It is transmitted by phlebotomine sand flies, with dogs as primary reservoir. Although human VL is a notifiable disease in Portugal, canine VL is not, which limits baseline surveillance. Description of the problem: In July 2024 a middle-age male outdoor worker presented at a clinic with 10 weeks of fever, weight loss, splenomegaly and hepatomegaly. He was referred to urgent care and subsequently hospitalized and diagnosed with VL. Following notification of the case, the Public Health Unit of West Local Health Unit in Portugal initiated a multidisciplinary epidemiological investigation which covered the period between November 2023 and August 2024. It followed a One Health approach and included patient interview, occupational and environmental field assessment, veterinary inquiry, entomological trapping and laboratory confirmation of the human case at the National Reference Laboratory. Results: The case was laboratory-confirmed. Appropriate treatment resulted in clinical improvement. Probable site of infection was the patient’s rural residential area, characterized by free-roaming dogs and nearby livestock farming. Sand fly traps (REVIVE program) yielded 13 phlebotomine sand flies, all of which tested negative for Leishmania. A local veterinary clinic reported a perceived increase in canine VL cases. No secondary human cases were identified. Risk was assessed as low (ECDC/UKHSA frameworks). Lessons: Multi-agency One Health coordination enabled a comprehensive and proportionate response. The absence of mandatory canine VL notification is a surveillance gap shared across Southern Europe, although its endemic state might partly explain this. Diagnostic delay is common in low-incidence diseases but highlights the need for improved clinician awareness in endemic-adjacent settings. Existing REVIVE infrastructure can be rapidly activated for entomological investigation. Key messages: • A structured One Health investigation of the first confirmed human visceral leishmaniasis case in the West region of Portugal since 2020 showed low community risk but critical surveillance gaps. • Integrating human, animal, and entomological data into a single response enables proportionate risk assessment for vector-borne diseases in low-incidence settings.
SN - 1101-1262
SN - 1464-360X
ER -