We detected
Leishmania mexicana in skin biopsies taken from a stray canine (
Canis familiaris
) and Texas mouse (
Peromyscus attwateri
) at two ecologically disparate sites in west and central Texas using polymerase chain reaction (PCR). A single PCR-positive dog was identified from a sample of 96 stray canines and was collected in a peri-urban area in El Paso County, Texas. The PCR-positive
P. attwateri was trapped at a wildlife reserve in Mason County, Texas, from a convenience sample of 20 sylvatic mammals of different species. To our knowledge, this represents the first description of
L. mexicana in west Texas and extends the known geographic range of the parasite to an area that includes the arid Chihuahuan Desert. Our finding of
L. mexicana in
P. attwateri represents a new host record and is the first description of the parasite in a wild peromyscid rodent in the United States.
