Veterinary research communications2026; 50(5); 381; doi: 10.1007/s11259-026-11328-8

Seroprevalence of Leptospira in Lavradeiro horses, a semi-feral ecotype from the Northern Brazilian Amazon.

da Silva Martins, A
·
Silva, TA
·
Heinemann, MB
·
Guedes, IB
·
Soares, RR
·
Dias, RA
·
Passos, RF
·
Braga, RM
·
Santos, FCCD
·
Borsanelli, AC

Abstract: Leptospirosis is a neglected zoonosis with significant impact on public and veterinary health, with equines acting as potential maintenance hosts of infection. This study aimed to investigate the seroprevalence of Leptospira in Lavradeiro horses under semi-feral conditions in Indigenous communities in the state of Roraima, Brazil. A total of 387 serum samples were subjected to the microscopic agglutination test (MAT), using antigens of Leptospira spp. from 18 serogroups. The overall prevalence was 15.8% (95% CI: 12.3-19.8%), with the most frequent serogroups being Australis, Tarassovi, Autumnalis, and Pomona. Seropositivity was higher among adult animals (17.6%) than foals (9.8%), although not statistically significant. Between sexes, there was no significant difference in positive females (16.8%) and males (14.7%). Horses that lived in areas that were likely to flood had a higher seroprevalence (23.6%). Titers of 800 or higher were found in 23 animals, most of which were from the municipality of Pacaraima. The Australis serogroup was the most common in this group. This study reports the first evidence of Leptospira exposure in Lavradeiro horses, with higher seroprevalence in flood-prone areas and reactivity to uncommon serovars. Our findings highlight pathogen circulation in equine under semi-feral conditions and the need for integrated surveillance and conservation of the Lavradeiro horse in the Northern Brazilian Amazon.

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Publication Date: 2026-06-09 PubMed ID: 42262427PubMed Central: PMC13249749DOI: 10.1007/s11259-026-11328-8Google Scholar: Lookup

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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

This study investigated how common exposure to Leptospira bacteria is among Lavradeiro horses living semi-wild in Indigenous communities of Northern Brazil.
It found that about 16% of these horses showed evidence of past or current infection, especially in areas prone to flooding, indicating ongoing circulation of the pathogen in this unique horse population.

Background

Leptospirosis: A zoonotic disease caused by bacteria of the genus Leptospira, affecting both humans and animals.
Significance: It is often neglected but can have serious health impacts and is maintained in certain animal populations.
Equine Role: Horses can act as maintenance hosts—animals that harbor and transmit the bacteria without necessarily showing symptoms.
Lavradeiro Horses: A semi-feral ecotype native to Northern Brazilian Amazon, living mostly in Indigenous territories where exposure to environmental pathogens may differ from domestic horses.

Study Objectives

To determine the prevalence (seroprevalence) of antibodies against Leptospira species in Lavradeiro horses.
To identify which serogroups of Leptospira are circulating in these horses.
To examine the influence of factors such as age, sex, and environmental conditions (like flood-prone areas) on seroprevalence.

Methods

Sample Collection: Serum samples were collected from 387 Lavradeiro horses living under semi-feral conditions.
Testing Method: Microscopic Agglutination Test (MAT) was used to detect antibodies against Leptospira spp. using antigens from 18 different serogroups.
Data Analysis: Prevalence and confidence intervals were calculated; comparisons were made between groups based on age, sex, and habitat characteristics.

Key Findings

Overall Prevalence: 15.8% of the horses tested positive for Leptospira antibodies.
Most Frequent Serogroups: Australis, Tarassovi, Autumnalis, and Pomona were the dominant serogroups detected.
Age Differences: Adults showed a higher prevalence (17.6%) compared to foals (9.8%), but this difference was not statistically significant.
Sex Differences: No significant difference was found between females (16.8%) and males (14.7%).
Environmental Influence: Horses living in flood-prone areas had a significantly higher seroprevalence (23.6%), suggesting environmental conditions facilitate bacterial exposure.
High Antibody Titers: 23 animals had titers of 800 or higher, predominantly from the Pacaraima municipality, mainly reacting to the Australis serogroup, indicating possible recent or intense exposure.

Interpretation and Implications

This study provides the first evidence of Leptospira exposure in the Lavradeiro horse ecotype.
Higher prevalence in flood-prone areas suggests that environmental factors like flooding increase risk, likely due to contamination of water and soil.
The detection of uncommon serovars implies diverse Leptospira strains circulate in this region.
Since Lavradeiro horses are semi-feral and associated with Indigenous territories, they might serve as reservoirs or indicators of environmental Leptospira presence, impacting animal and potentially human health.
Findings support the need for integrated surveillance programs combining veterinary and public health measures, especially in remote Amazon communities.
The research also highlights the importance of conservation efforts for the Lavradeiro horse, considering their ecological and cultural significance, and their role in disease ecology.

Conclusions

Leptospira infection is present and circulating among Lavradeiro horses in the Northern Brazilian Amazon.
Environmental factors such as flooding play a key role in exposure risk.
There is a need for continued monitoring and coordinated health strategies to manage leptospirosis in semi-feral horses and associated ecosystems.

Cite This Article

APA

da Silva Martins A, Silva TA, Heinemann MB, Guedes IB, Soares RR, Dias RA, Passos RF, Braga RM, Santos FCCD, Borsanelli AC. (2026). Seroprevalence of Leptospira in Lavradeiro horses, a semi-feral ecotype from the Northern Brazilian Amazon. Vet Res Commun, 50(5), 381. https://doi.org/10.1007/s11259-026-11328-8

Publication

Veterinary research communications

ISSN: 1573-7446

NlmUniqueID: 8100520

Country: Switzerland

Language: English

Volume: 50

Issue: 5

PII: 381

Researcher Affiliations

da Silva Martins, Andressa

Departament of Preventive Veterinary Medicine, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.

Silva, Tamires Ataides

Departament of Preventive Veterinary Medicine, Universidade Federal de Goiás, Goiânia, Goiás, Brazil.

Heinemann, Marcos Bryan

Department of Preventive Veterinary Medicine and Animal Health, Universidade de São Paulo, São Paulo, Brazil.

Guedes, Israel Barbosa

Department of Preventive Veterinary Medicine and Animal Health, Universidade de São Paulo, São Paulo, Brazil.

Soares, Rafael Rodrigues

Department of Preventive Veterinary Medicine and Animal Health, Universidade de São Paulo, São Paulo, Brazil.

Dias, Ricardo Augusto

Department of Preventive Veterinary Medicine and Animal Health, Universidade de São Paulo, São Paulo, Brazil.

Passos, Rebeca Farias

Veterinary, Student at Graduate Program in Animal Reproduction in the Amazon (ReproAmazon), Pará, Brazil.

Braga, Ramayana Menezes

Embrapa Roraima, Boa Vista, Roraima, Brazil.

Santos, Fernanda Carlini Cunha Dos

Universidade Federal dos Vales do Jequitinhonha e Mucuri, Unaí, Minas Gerais, Brazil.

Borsanelli, Ana Carolina

Departament of Preventive Veterinary Medicine, Universidade Federal de Goiás, Goiânia, Goiás, Brazil. anaborsanelli@ufg.br.

Conflict of Interest Statement

Declarations. Ethical approval: This study was approved by the Ethics Committee on Animal Use of the Universidade Federal de Roraima (protocol No. 002/2021). Competing interests: The authors declare no competing interests.

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