Abstract
This paper describes clinical signs and lesions in two cases of leishmaniosis—one visceral and one cutaneous in the cat (Felis catus domesticus). The diagnosis was achieved by a combination of serology, light and electron microscopic studies. The vague nature of the clinical signs observed in both cases was particularly striking, and clinical features were similar to many other diseases commonly found in cats. Therefore, the use of various investigations to detect leishmaniosis (serum chemistry, serology and histopathology) is highly recommended in cases where clinical signs do not respond to conventional treatment.
Leishmaniosis is a zoonosis affecting mainly man and dogs. However, many animal species may act as reservoirs for the organism, including various wild carnivores (wolf, fox and wild cats), wild rodents, goats, calves, horses and cats (Bonfante et al 1991, Barnes et al 1993, Euzeby 1994, Hervás et al 1996a, b).
Cutaneous leishmaniosis has been reported in cats in various countries. Typical signs include crusty ulcers on the lips, nose, eyelids and edge of the pinnae, symmetric alopecia and desquamation, and the appearance of nodules on the pinnae (Bergeon 1927, Giordano 1993, Barnes et al 1993, Costa Durao et al 1994, Merchant & Taboada 1995, Lareulle-Magallon & Toga 1996). Visceral leishmaniosis, however, is not common in cats, although single cases have been reported in Asia, America and the Mediterranean area, where the parasite was detected, with or without signs of illness, in visceral locations (Bergeon 1927, Giordano 1933, Gimeno 1933, Ferreira et al 1938).
In Spain, leishmaniosis due to Leishmania infantum is an extremely common disease, both in terms of the high prevalence of this parasite in dogs—over 10%—(Martínez 1991), and the hazard zoonosis represents to human health. However, very few cases of leishmaniosis have been reported in cats in the Mediterranean area, and these have mainly involved cutaneous manifestations (Bergeon 1927, Giordano 1933, Costa Durao et al 1994).
This paper describes the first cases of feline visceral and cutaneous leishmaniosis reported in Spain.
Materials and Methods
Two cases are described.
Case 1
A 5-year-old female, domestic shorthair cat was admitted with severe jaundice and vomiting, and died shortly after hospitalisation. A post-mortem examination was performed, and viscera were fixed in 10% formalin and referred to this laboratory for analysis.
Visceral material was routinely processed for light microscopy. Samples referred for ultra-structural analysis were fixed in formaldehyde, washed in phosphate-buffered saline (PBS, pH 7.4) and routinely processed for transmission electron microscopy.
Case 2
A 3-year-old female, domestic shorthair cat had a history of abortions and recurrent alopecia of the abdomen and head (Fig 1), together with ulceration of bony protrusions.
Case 2—cutaneous leishmaniosis. Alopecia of the ear and head.
Clinical examination revealed ulceration over the ischial bone protrusions, desquamation with diffuse bilateral alopecia of the posterior third of the abdomen, desquamation and alopecia and erythaema of the edge of the ears. Appreciable enlargement of the popliteal lymph nodes was also found.
On routine haematology and serum biochemistry, the only notable finding was a slight increase in the eosinophil count.
Additional investigations were undertaken. Serum proteins were separated by zone electrophoresis using standard method (Atom 503, Scantom) and serum titre of anti-Leishmania antibodies was determined using a commercial indirect immunofluorescence (IIF) assay for Leishmania antibodies detection (Bio-Merieux). A fine needle aspirate was obtained from a popliteal lymph node and smears were stained with Giemsa.
Results
Case 1
At post-mortem examination the most significant gross changes were an enlarged discoloured liver and a severely enlarged black spleen.
Histopathological examination of the liver showed evidence of multi-focal granulomatous hepatitis, particularly intense in the portal regions, with multiple granulomas formed by macrophages with foamy cytoplasm containing a large number of Leishmania sp amastigote forms, numerous plasma cells and lymphocytes. Hepatocytes contained abundant biliary pigment and evidence of steatosis. The spleen showed lymphocyte depletion with proliferation of the macrophage sheath, which was formed by cells with abundant cytoplasm containing visible protozoan Leishmania sp structures. Hypercellularity, associated with the presence of a large number of activated and parasitised macrophages, was observed in red splenic pulp (Fig 2). A moderate number of megakaryocytes were also observed. Lymph nodes showed lymphocyte depletion and proliferation of activated macrophages. Examination of renal glomeruli showed evidence of membranous glomerulonephritis with focal mesangial hyaline (electron dense, in ultrastructural studies) deposits. There was widespread interstitial lymphoplasmocytic nephritis, which had also infiltrated the renal pelvis and the tunica media of large kidney vessels.
Spleen, Case 1—visceral leishmaniosis. Large number of activated macrophages containing numerous amastigotes forms of Leishmania sp. Haematoxylin and eosin. Original magnification ×630.
Lymphoplasmocytic gastritis was observed in the stomach, with a moderate infiltrate in the lamina propria by a mixture of plasma cells, lymphocytes and macrophages. Amastigote Leishmania sp forms were visible in macrophages, particularly in the apical position. This infiltrate was much more intense, and parasitic macrophages more widespread, in the stomach submucosa. An intense diffuse inflammatory infiltrate was observed in the mucosa and submucosa of the large intestine. The infiltrate was composed of numerous macrophages containing various Leishmania sp amastigote forms, lymphocytes and plasma cells.
Ultrastructural examination of these organs confirmed massive infestation of macrophages by Leishmania sp amastigote forms, characterised by a trilaminar envelope with subpedicular microtubules, a nucleus, a kinetoplast containing helical mitochondrial DNA and a flagellum (Fig 3).
Spleen, Case 1—visceral leishmaniosis. Ultrastructural study showing numerous forms of Leishmania sp Original magnification ×8200.
Case 2
The study of the smear revealed numerous protozoan amastigotes resembling Leishmania sp (Fig 4). The serological (IIF) study revealed an antibody titre of 1/160 (negative reference value 1/80), and significant changes were observed in electrophoresis values (with elevations in beta and gamma globulins—Table 1). Following these investigations, the animal was treated with meglumine antimonate (Glucantime; Rhône Mérieux) at dose of 5 mg/kg subcutaneosly, and ketoconazole (Panfungol; Esteve) at 10 mg/kg orally. This combination was used for three cycles of 4 weeks duration, leaving 10 days without therapy between each treatment period. This resulted in resolution of the cutaneous lesions.
Lymph node, Case 1—cutaneous leishmaniosis. Smear of aspirate from popliteal lymph node with numerous protozoan amastigotes resembling Leishmania sp.
Protein electrophoresis results from case 2
Discussion
Leishmaniosis is a zoonotic disease caused by an intracellular protozoan of the genus Leishmania. This disease is endemic in the Mediterranean area, the Middle and Far East, and areas of Central America and Central Africa. However, there have been few reports of cats acting as hosts for Leishmania sp (Ferreira et al 1938, Euzeby 1994), and very few cases of leishmaniosis in cats have been reported in the Mediterranean area (Bergeon 1927, Giordano 1933, Costa Durao et al 1994). Those cases that have been reported, refer mainly to cutaneous manifestations of the disease.
Cutaneous feline leishmaniosis may in fact be more widespread than has been documented (Ashford & Bettini 1987, Ashford 1989, Barnes et al 1993). It may easily be overlooked during clinical investigations due to the wide variety of non-specific pathological signs which this disease induces (Shaw & Laison 1987, Barnes 1993, Lareulle-Magallon & Toga 1996). Detection is further hindered by the few pathological signs presented in infected cats (Lareulle-Magallon & Toga 1996), perhaps attributable to a high degree of natural resistance to the organism in cats, as evidenced in experimental infection with L donovani and L chagasi (Kirkpatrick 1984).
With dermatological disease of undetermined cause, additional diagnostic tests including serology, blood smears, cytology of lymph node aspirates and perhaps also bone marrow, should be performed to rule out the presence of leishmaniosis. In comparison with feline leishmaniosis, it appears that serological and serum protein electrophoretic alterations are generally much more profound in canine leishmaniosis (Athias 1991, Merchant & Taboada 1995). Furthermore, the vagueness of the cutaneous manifestations of leishmaniosis in cats may lead to the prescription of antimycotic agents (imidazoles), which could improve the clinical condition but do not address the true underlying aetiology.
Lymphocyte depletion with proliferation of parasitised macrophages has been reported in canine visceral leishmaniosis (Keenan et al 1984), suggesting impaired cellular immunity (Carvalho et al 1981, Keenan et al 1984). In case 1, with visceral presentation, pathological findings in lymph nodes and spleen could potentially have been a morphological manifestation of an underlying immunological dysfunction, allowing active multiplication and dissemination of the parasite in viscera. Immunosuppressive agents, such as feline immunodeficiency virus (FIV), feline leukaemia virus (FeLV) or stress, may induce immunological dysfunction, with impaired cellular immune response, allowing active multiplication of the parasite and widespread visceral dissemination of the protozoa. Unfortunately, tests for FeLV and FIV were not performed in either of the two cases presented here.
Footnotes
Acknowledgements
The authors would like to thank Professor T Moyano, Chief of Electron Microscopy of the University of Cordoba (Spain) for his support and technical assistance.