Review spotlights locally acquired leishmaniosis in U.S. animals: full analysis
A newly published review in Microorganisms argues that autochthonous leishmaniosis in the United States deserves broader veterinary attention because it is already documented in multiple animal species, not just in imported dogs or in human travel-associated cases. The authors summarize evidence of locally acquired infection in dogs, cats, horses, and wildlife, and frame the issue as a One Health concern tied to reservoirs, vectors, animal movement, and missed recognition in clinical practice. (mdpi.com)
That matters because leishmaniasis is still often thought of in U.S. practice as an imported disease. CDC says most human cases diagnosed in the U.S. were acquired abroad, but locally acquired cutaneous leishmaniasis does occur, especially in Texas, and possibly in Arizona and Oklahoma. The new review builds on that backdrop by focusing on animals, where the epidemiology is more complex and, in dogs at least, may include long-standing domestic transmission chains. (cdc.gov)
Among the review’s key takeaways: autochthonous canine cases in the U.S. have been associated with L. infantum, and horses with L. martiniquensis. The paper also notes a distinctive genotype among Texas L. mexicana isolates and maps higher endemicity risk to states where both parasites and competent sand fly vectors have been documented. Texas stands out most clearly, while Arizona is described as facing a similar level of concern because autochthonous infections have been found in humans and wildlife, even though vector data there are less complete. (mdpi.com)
The canine history is especially important for veterinarians. A CDC-led survey published in Emerging Infectious Diseases found confirmed Leishmania infantum infection in foxhounds from 58 hunt clubs or kennels across 18 U.S. states and 2 Canadian provinces, with newly seroconverted cases detected during the study period. That investigation concluded canine visceral leishmaniasis was enzootic in foxhounds and suggested transmission in this population was predominantly dog-to-dog, rather than through a broader wildlife reservoir or obvious spillover into people. (wwwnc.cdc.gov)
Subsequent CDC-linked work strengthened that picture. Experimental work showed that L. infantum from infected U.S. hounds can remain infective in sand flies, which means vectorborne spread is biologically plausible. But a 2024 CDC risk assessment said vertical transmission from infected dams to pups appears to be the dominant mode of spread in the United States, and noted that no evidence of vectored L. infantum transmission among U.S. dogs or humans has been reported to date. Another CDC study in 2022 used genomic data to support persistent vertical transmission in U.S. hunting hounds. (stacks.cdc.gov)
Direct expert reaction to this specific review was limited in publicly available sources, but the broader veterinary and public health literature is consistent: clinicians shouldn’t assume leishmaniosis requires international travel. CDC has published a case report of L. infantum in a U.S.-born dog and noted that veterinarians may overlook the diagnosis when an animal lacks travel history. Merck Veterinary Manual similarly notes the disease occurs intermittently in North America, especially in foxhounds. (wwwnc.cdc.gov)
Why it matters: For veterinary teams, this review is less about a sudden new outbreak than about diagnostic reframing. In the right patient, chronic dermatologic lesions, lymphadenopathy, ocular disease, epistaxis, weight loss, or protein-losing nephropathy may warrant leishmaniosis on the list even if the pet parent reports no foreign travel. The review also underscores that species identification matters: U.S. animal cases are not all the same parasite, not all the same transmission pattern, and not all the same regional risk. That has implications for diagnostics, case reporting, breeding decisions, blood donor screening, and conversations with pet parents about zoonotic risk and preventive measures. (mdpi.com)
What to watch: The next questions are practical ones: whether surveillance expands in veterinary and wildlife populations, whether more state-level guidance emerges in higher-risk areas, and whether dog importation, interstate movement, or ecological change alter the current balance between vertical and vectorborne transmission. The CDC’s recent importation risk work suggests those pathways are now being examined more systematically, which could eventually shape screening and prevention recommendations. (wwwnc.cdc.gov)