Defining the Molecular Epidemiology of Leishmaniasis in Texas Through a One Health Approach.

Leishmaniasis, caused by Leishmania spp., is a neglected tropical disease with a significant global health burden. It is estimated to affect over 6.2 million people globally, with over 1 million incident cases anually. While cutaneous leishmaniasis is considered endemic to tropical and subtropical regions of South America, Central America, and Mexico, Leishmania has also been quietly spreading northward and establishing itself in the United States. Autochthonous transmission of Leishmania occurs in several areas, including Texas, where diagnosed cases of cutaneous leishmaniasis are predominately acquired locally. Understanding the impact of leishmaniasis in the US is compounded by the challenge of early detection and diagnosis, as symptoms resemble those of other common skin conditions, so cases are often misdiagnosed or missed completely. Thus, passive surveillance is ineffective for detecting the true burden of disease, and even the mandatory reporting in Texas frequently misses cases. We critically need multi-level epidemiologic studies that include human, vector, and animal infection dynamics to fully understand the specific risk of Leishmania transmission. However, such studies do not currently exist. Therefore, we propose conducting a One Health investigation into the transmission of Leishmania in two major metropolitan areas in Texas: Houston and Dallas. We will first analyze hospital-based data of locally acquired leishmaniasis from major medical systems in Houston and Dallas, which will inform our sandfly surveillance investigations to elucidate this parasite’s burden and distribution in these areas. Additionally, we will test shelter dogs to identify enzootic transmission. Our preliminary data suggests that the prevalence of Leishmania in Texas vectors and animals is significantly higher than previously published. Our central hypothesis is that Leishmania is endemic in sandfly vectors throughout Texas, with a disproportionate burden in north- central Texas, and is causing disease in major metropolitan areas. Our aims are as follows: (1) Determine the prevalence of Leishmania in sandfly vectors through untargeted and targeted collections informed by locations of autochthonous human cases in Harris and Dallas County, Texas, and (2) Determine the prevalence of Leishmania-positive domestic dogs in Harris and Dallas County, Texas. The proposed research represents a foundational study to evaluate disease transmission and provide critical data for public health decision making. Our long-term goals are to define the geospatial epidemiology of leishmaniasis in the southern United States, and to design targeted public health interventions to prevent transmission. This study brings together a collaborative team to begin to tackle a growing public health problem with no active surveillance testing funded by other means. Our findings will critically impact our understanding of leishmaniasis as this disease continues to invade the US and will allow us to identify high-risk populations for targeted prevention and intervention efforts. Project Number: 1R21AI196981-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Sarah Gunter (+1 co-PI) | Institution: BAYLOR COLLEGE OF MEDICINE, HOUSTON, TX | Award Amount: $461,187 | Activity Code: R21 | Study Section: Transmission of Vector-Borne and Zoonotic Diseases Study Section [TVZ] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R21AI19698101