Leishmaniosis is caused by protozoal parasites of the genus Leishmania. Key clinical signs of leishmaniosis in cats are similar to those in dogs, ranging from cutaneous lesions to more-systemic clinical signs, such as lymphadenomegaly and ocular lesions. Diagnosis is often based on serological testing; however, antibody production in cats is commonly not as marked as in dogs. Therefore, if the serological test result is negative or low positive, other diagnostic tests, such as cytological or histological evaluation should be used, along with immunohistochemical testing and PCR assay. Treatment options are limited because of a lack of published information and a lack of data on drug efficacy and safety. However, they include the use of allopurinol as monotherapy.
Leishmaniosis is caused by protozoal parasites of the genus Leishmania. Leishmaniosis is a major zoonosis.
Among nonhuman animals, most clinical cases of leishmaniosis are reported in dogs; however, cats, as well as horses and other mammals, can also be infected.
Leishmaniosis is also called leishmaniasis, especially when referring to cases in humans; however, the terms are sometimes used interchangeably.
Etiology of Leishmaniosis in Cats
The etiological agents of leishmaniosis are protozoal parasites of the genus Leishmania (order Trypanosomatida, family Trypanosomatidae, subfamily Leishmaniinae). More than 23 species of Leishmania have been described, most of which are zoonotic.
At least seven Leishmania species infect cats. The most important Leishmania parasite to affect cats is Leishmania infantum (1).
Epidemiology of Leishmaniosis in Cats
Feline Leishmania infections, observed all over the world, are caused by the species commonly found in other animals in a given region; the prevalence in cats is usually lower than that in dogs in the same area.
Leishmania is most likely transmissible from cats to sand flies, because sand flies have been shown to feed on cats and to be infected after feeding on naturally infected cats (2).
To date, nonvectorial transmission has not been described in cats; however, blood transfusion could be a source of infection in cats, as it is in humans and dogs.
Host factors predisposing to susceptibility include immunocompromise secondary to feline immunodeficiency virus (FIV) or feline leukemia virus (FeLV) infection, immunosuppressive therapies, or debilitating concomitant diseases (3).
Clinical Findings of Leishmaniosis in Cats
Feline leishmaniosis is a chronic disease with clinical signs and clinicopathological abnormalities mirroring those found in leishmaniosis in dogs (4).
The two most common clinical findings of leishmaniosis in cats are skin and/or mucocutaneous lesions (see ulcerative dermatitis image) and lymphadenomegaly. The most common clinicopathological abnormality is hypergammaglobulinemia.
Courtesy of Dr. Maria Grazia Pennisi.
Diagnosis of Leishmaniosis in Cats
Serological testing
Cytological or histological evaluation
Quantitative PCR assay
Culture
For cats that show clinical signs consistent with leishmaniosis, the diagnosis should be confirmed via quantitative serological evaluation. In suspected cases, patients should be tested for feline retroviruses (FeLV and FIV).
Pearls & Pitfalls
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Cats tend to have less marked antibody responses, compared with dogs. If serological testing produces a negative result but the clinical picture is highly suggestive of leishmaniosis, other diagnostic techniques (eg, cytological or histological evaluation, quantitative PCR assay, or culture) should be considered.
Treatment of Leishmaniosis in Cats
Limited treatment options
Allopurinol
There are no published controlled studies on the treatment of cats with leishmaniosis.
Without evidence indicating otherwise, empirical treatment with allopurinol (10 mg/kg, PO, every 12 hours for at least 6 months) has been used most frequently, without reported adverse effects.
Prevention of Leishmaniosis in Cats
Most pyrethroid-based products are toxic to cats. Flumethrin collars are licensed for use in cats (5).
There are no available vaccines against leishmaniosis for cats.
Key Points
Leishmania infantum infection in cats has been documented primarily in areas where leishmaniosis is prevalent in dogs; however, the disease tends to be less common in cats. FeLV- or FIV-positive cats have a higher probability of being seroreactive to Linfantum antigen.
Clinical signs of leishmaniosis in cats are similar to those in dogs. Cats can also present with subclinical infection, mild self-limiting disease, or moderate to very severe non-self-limiting disease.
Limited preventive measures and treatments are available for cats.
For More Information
WHO: Leishmaniasis
CDC: Leishmaniasis
Also see pet owner content regarding leishmaniosis in cats.
References
Pereira A, Maia C. Leishmania infection in cats and feline leishmaniosis: an updated review with a proposal of a diagnosis algorithm and prevention guidelines. Curr Res Parasitol Vector Borne Dis. 2021;1:100035. doi:10.1016/j.crpvbd.2021.100035
Maroli M, Pennisi MG, Di Muccio T, Khoury C, Gradoni L, Gramiccia M. Infection of sandflies by a cat naturally infected with Leishmania infantum. Vet Parasitol. 2007;145(3-4):357-360. doi:10.1016/j.vetpar.2006.11.009
Priolo V, Masucci M, Donato G, et al. Association between feline immunodeficiency virus and Leishmania infantum infections in cats: a retrospective matched case-control study. Parasit Vectors. 2022;15(1):107. doi:10.1186/s13071-022-05230-w
Pennisi MG. Leishmaniosis of companion animals in Europe: an update. Vet Parasitol. 2015;208(1-2):35-47. doi:10.1016/j.vetpar.2014.12.023
Brianti E, Falsone L, Napoli E, et al. Prevention of feline leishmaniosis with an imidacloprid 10%/flumethrin 4.5% polymer matrix collar. Parasit Vectors. 2017;10(1):334. doi:10.1186/s13071-017-2258-6
