Leishmaniosis in a cat with chronic diarrhea as the only clinical manifestation

Abstract A 10‐year‐old male domestic shorthaired cat was presented with chronic diarrhea unresponsive to treatment. Laboratory testing identified hyperglobulinemia and mild nonregenerative anemia, and nongastrointestinal causes of diarrhea were ruled out. Gastrointestinal endoscopy and biopsy were performed and disclosed diffuse generalized granulomatous and lymphoplasmocytic inflammatory reaction in all segments of gastrointestinal tract evaluated, with numerous Leishmania spp. amastigotes within the cytoplasm of macrophages. The organism also was detected in spleen and bone marrow and Leishmania spp. serology was positive (immunofluorescence assay 1 : 160). A diagnosis of granulomatous enteritis secondary to leishmaniosis was made. Gastrointestinal signs resolved after treatment with allopurinol and a dietary supplement of nucleotides and active hexose‐correlated compounds (N‐AHCC), but seropositivity and gammopathy persisted 8 months later. The cat died of unrelated causes after an additional 3 months and permission for necropsy was not granted. Leishmaniosis as a cause of chronic diarrhea has not been reported previously in cats and should be considered in endemic areas in cats with chronic gastrointestinal signs.


| INTRODUCTION
Leishmaniosis is an endemic disease in the Mediterranean area of Europe caused by the protozoan Leishmania infantum and transmitted by phlebotomine sand flies. 1 Limited information is available on epidemiological and clinical aspects of Leishmania spp. infection in cats, but it appears to be an emerging disease in this species, more frequently reported in recent decades in endemic areas. 1,2 Clinical disease in cats is rare, and clinical signs usually reflect cutaneous and ocular disease, with or without visceral involvement. 1,2 Chronic diarrhea is an uncommon primary presentation of leishmaniosis (L opez M, Bertolani C, Sainz A, et al. Chronic diarrhea as a main clinical sign of canine leishmaniosis: 22 cases Proceedings of the 2020 ECVIM congress). In dogs, gastrointestinal signs most commonly are related to chronic renal disease. 3 Similarly, vomiting and diarrhea Abbreviations: FeLV, feline leukemia virus; FIV, feline immunodeficiency virus; fPLI, feline pancreatic lipase; fTLI, feline trypsin-like immunoreactivity; N-AHCC, nucleotides and active hexose correlated compounds; RBC, red blood cells; T4, total thyroxine; UPC, urinary protein/creatinine ratio. have been reported sporadically in some cats with leishmaniosis, although not associated with primary gastrointestinal disease. 1

| CASE DESCRIPTION
A 10-year-old male neutered domestic shorthaired cat was presented for evaluation of chronic diarrhea. The cat lived in a multicat household and lived both indoors and outdoors. The cat had not received any vaccinations or treatment for intestinal parasites and ate a commercial maintenance dry food. On presentation, the main owner complaints were mild weight loss and small bowel diarrhea that started 4 weeks before presentation, and was not responsive to previous dietary changes and antibiotic treatment.
Mild scaly dermatitis and poor body condition (body condition score 3/9; 3.7 kg) were noted on physical examination. No abnormalities were detected on abdominal palpation and peripheral lymph nodes were slightly enlarged. Laboratory testing (CBC, serum biochemical profile and urinalysis) identified a mild nonregenerative anemia and hyperglobulinemia (Table 1). Mild proteinuria was detected.
Two months later, the cat weighted 4.18 kg. Initially, partial improvement in clinical signs occurred, but diarrhea persisted. At this time hematology disclosed worsening of anemia and globulin concentration was persistently increased (Table 1). Serum total thyroxine concentration (T4), feline trypsin-like immunoreactivity (fTLI) and feline pancreatic lipase (fPLI) concentration were within normal limits, and serum cobalamin concentration was increased ( were negative (SNAP Combo Plus IDEXX, Hoofddorp, Netherlands).
Abdominal ultrasound examination identified splenomegaly with a mottled or honeycomb appearance ( Figure 1) and slight increase in thickness of the duodenum (2.6 mm). Fine needle aspiration of spleen and lymph node were performed and Leishmania spp. amastigotes were detected on cytology. Bone marrow cytology also was performed, and Leishmania spp. amastigotes were detected both free and in the cytoplasm of macrophages.
Anti-Leishmania spp. antibodies were detected by immunofluorescence assay at a titer of 1 : 160 (Inmunovet, Barcelona, Spain), and serum electrophoresis indicated a mild increase in alpha-2 globulins and a polyclonal gammopathy. Histologically, a diffuse generalized granulomatous and lymphoplasmocytic inflammatory reaction was found within the lamina propria of the mucosa, more severe in the duodenum, but also in the stomach, ileum, and cecum. Intracellular parasitic forms morphologically consistent with Leishmania spp. amastigotes were seen within the cytoplasm of numerous macrophages throughout the gastrointestinal tract ( Figure 2).
The presence of Leishmania spp. was confirmed by immunohistochemical staining (Figure 3) Findings from endoscopy and histopathology in the cat of the present report were similar to those reported in dogs, where patches of hyperemic, edematous, irregular and mildly erosive colonic mucosa are commonly encountered, and the most frequent inflammatory pattern is pyogranulomatous. 7 Although in our case the inflammation was more severe in the small intestine, the entire gastrointestinal tract was affected, and the inflammation was primarily granulomatous and lymphoplasmocytic.
Underlying immunological dysfunction may allow active multiplication of the parasite and clinical disease in cats, as has been suggested in some reports that have found leishmaniosis more frequently in immunosuppressed cats or those with coexisting diseases. 13  This report describes a novel clinical presentation of leishmaniosis in a cat with primary gastrointestinal signs. Because clinical leishmaniosis is rare in cats and these clinical signs are not commonly recognized features of the disease, it may be underdiagnosed. Therefore, in endemic areas, leishmaniosis should be considered in cats with chronic gastrointestinal signs, especially diarrhea.

ACKNOWLEDGMENT
No funding was received for this study.