Review spotlights locally acquired leishmaniosis in U.S. animals

A newly published review in Microorganisms argues that autochthonous leishmaniosis in the United States deserves broader veterinary and public health attention, not only in dogs, but also in cats, horses, and wildlife. The paper frames leishmaniosis as an established, if still underrecognized, domestic issue, and calls for stronger One Health surveillance to better define reservoirs, transmission routes, and spillover risk. (pubmed.ncbi.nlm.nih.gov)

That framing builds on a long, uneven U.S. history with the parasite. CDC says most diagnosed human cases in the U.S. are still tied to travel or residence abroad, but locally acquired cutaneous leishmaniasis has been reported, especially in Texas, and rarely in Oklahoma and Arizona. In animals, the best-known U.S. story has centered on foxhounds and other hunting dogs, where Leishmania infantum has circulated for decades and has been treated as an enzootic problem rather than a one-off importation event. (cdc.gov)

The new review’s main contribution is synthesis across species. According to the PubMed record, the authors examine autochthonous infection in dogs, cats, horses, and wildlife, and specifically highlight transmission pathways, the roles different animals may play in endemicity, and the possible implications for human health. That broader lens matters because veterinary discussion in the U.S. has often focused narrowly on canine visceral leishmaniosis in hounds, while feline, equine, and wildlife findings have stayed more fragmented in the literature. (pubmed.ncbi.nlm.nih.gov)

The canine evidence base remains the strongest. CDC researchers reported in 2006 that canine visceral leishmaniasis was enzootic in foxhounds in 18 U.S. states and 2 Canadian provinces during 2000 to 2003. A later CDC genomic study, published in 2022, found that a U.S. hound L. infantum population was likely introduced from Europe and then maintained largely through vertical transmission, with no demonstrated recent recombination signal pointing to sustained vector-driven spread in that population. The authors also noted that experimental vectorborne transmission from U.S. hounds has been shown, but naturally infected sand flies carrying L. infantum have not been found in the U.S. to date. (wwwnc.cdc.gov)

Outside dogs, the clinical and epidemiologic picture is less settled, but still relevant. Merck Veterinary Manual notes that feline leishmaniosis occurs worldwide, usually at lower prevalence than in dogs in the same region, and often presents with skin or mucocutaneous lesions and lymphadenomegaly. In dogs, Merck also notes transfusion-associated transmission and likely direct dog-to-dog transmission in some settings, reinforcing why breeding, blood banking, and contact history can matter when evaluating unexplained compatible disease. (merckvetmanual.com)

There wasn’t much fresh quote-driven reaction to this review in the search results, but the broader veterinary infectious disease conversation has been consistent for years: imported and locally maintained vector-borne pathogens can sit below the radar until they show up in breeding networks, rescue pipelines, or referral caseloads. Scott Weese, writing previously about canine importation and leishmaniasis risk, has argued that these cases illustrate the animal and public health consequences of moving dogs across borders without enough infectious disease scrutiny. That’s not a direct response to this paper, but it aligns with the review’s emphasis on surveillance and transmission awareness. (wormsandgermsblog.com)

Why it matters: For veterinarians, this review is less about a sudden outbreak than about diagnostic posture. If leishmaniosis is treated as exclusively exotic, clinicians may miss locally acquired or vertically transmitted infections, especially in dogs with compatible systemic signs, dermatologic disease, breeding links, transfusion exposure, or hound ancestry. It also reinforces the need to think across species and practice types: small animal clinicians may see the index case, shelter and community medicine teams may encounter population-level risk factors, and public health or wildlife partners may be needed to clarify whether a case reflects spillover, silent endemicity, or a changing vector landscape. (pubmed.ncbi.nlm.nih.gov)

What to watch: The next big questions are whether broader surveillance finds more non-canine reservoirs, whether natural vector transmission of L. infantum in U.S. animal populations is documented more clearly, and whether state or federal agencies update guidance around testing, blood donor screening, or case reporting as the evidence base grows. (pubmed.ncbi.nlm.nih.gov)