Lack of leishmania spp. detection in a molecular survey of high-risk domestic cats from the southcentral USA.

Endemic transmission of cutaneous leishmaniasis, primarily caused by Leishmania (Leishmania) mexicana complex, has become increasingly recognized in the southcentral USA. Veterinary species could play a role in the epidemiology of L. (L.) mexicana in the USA, and feline cutaneous leishmaniasis caused by L. (L.) mexicana has been reported in Texas, overlapping in distribution with human incidence. The primary aim of this study was to evaluate high-risk cats from shelters in Texas and Oklahoma for infection with Leishmania spp. by qPCR. Tissue samples were opportunistically collected post-mortem from 213 domestic cats under shelter jurisdiction in Texas (n = 182) and Oklahoma (n = 31) between June and August 2025. Four tissue samples were collected from each cat including skin, spleen, mesenteric lymph node, and bone marrow. Demographic information including animal location, sex, age, breed, and the presence of cutaneous lesions were recorded to evaluate potential risk factors of infection. Genomic DNA was extracted from each tissue sample and screened for Leishmania spp. DNA by a probe-based qPCR targeting a conserved fragment of the 18S rRNA gene. The qPCR assay was validated for the detection of Leishmania DNA using a skin biopsy sample from a cat with naturally-acquired cutaneous leishmaniasis and originating from Quintana Roo State, Mexico. Assay validation confirmed the qPCR assay's ability to amplify L. mexicana DNA within feline tissue. The surveyed feline population from Texas and Oklahoma included 52.1% males and 47.9% females, with age group distribution of <3 months (45.5%), 3-6 months (8.5%), 6 months-1 year (7.0%), and > 1 year (39.0%). A small proportion of cats, 5.2%, had cutaneous lesions. Leishmania spp. DNA was not detected in tissue samples from any cat. In the absence of positive samples, further evaluation of risk factors was not performed. This study is the largest survey for Leishmania spp. infection in domestic cats in the southcentral USA, and the only survey to include cats from counties beyond El Paso, Texas, located along the Mexican border. Though Leishmania spp. was not detected in cats surveyed in this study, the role of cats in the epidemiology of cutaneous leishmaniasis in this region should not yet be discounted. Further studies including a larger population size, older animals, more sampling locations, or the addition of serological testing may strengthen our epidemiological understanding and help to overcome limitations of this study.