Clinical management of feline trypanosomiasis (Trypanosoma evansi) in six domestic short-haired cats

Introduction

Trypanosomiasis is a zoonotic protozoal parasitic disease that affects a wide range of domestic and wild animals as well as humans (Panigrahi et al., 2015) [13] . The disease is caused by protozoan parasites belonging to the genus Trypanosoma, of which Trypanosoma evansi and Trypanosoma brucei are the most common species responsible for animal infections. Transmission occurs primarily through the bites of hematophagous insect vectors such as tsetse flies, Tabanus (horse flies), Stomoxys (stable flies), and Triatomine bugs (kissing bugs). These vectors transmit the parasite by injecting infective trypomastigotes into the skin of the host during blood feeding. (Singh et al., 1993) [15] . Although trypanosomiasis is widely recognized as a disease of large domestic animals such as cattle, camels, and horses in Africa and Asia, (Lun and Desser, 2013) [7] , infections have also been reported in other vertebrate hosts (Da Silva et al., 2005a, Dávila and Silva, 2009, Herrera et al., 2004, Joshi et al., Tarello, 2008) [2,5,10,16] including cats. However, feline trypanosomiasis is relatively rare, as cats appear to exhibit a higher degree of natural resistance compared to other vertebrate hosts.In addition to vector transmission, cats may also acquire infection through ingestion of carcasses of infected animals (Nwoha, 2013) [12] . Geographically, feline trypanosomiasis has been documented in several regions including India, Iraq, and Indonesia, suggesting that while uncommon, the disease should be considered in differential diagnoses of feline patients showing signs of anemia, neurological abnormalities, or wasting in endemic areas.

Materials and Methods

Six domestic short-haired cats, aged between one and two years (four males and two females), were presented to the Veterinary Clinical Complex, Rajendra Nagar, with a history of anorexia, fever corneal opacity and progressive weakness were selected for present study. According to the owners, none of the cats had been previously vaccinated or dewormed. Detailed physical and clinical examination done. Based on the clinical presentation and case history, hemoprotozoan infection was suspected. Blood samples were collected aseptically from the cephalic vein of each cat into EDTAcoated tubes for hematological and parasitological evaluation. Wet blood films and Giemsa-stained thin smears were prepared and examined microscopically under oil immersion (100× magnification) for the detection of trypanosomes. Routine hematological parameters, including total erythrocyte count (TEC), total leukocyte count (TLC), hemoglobin concentration, and platelet count, were analyzed using an automated hematology analyzer to assess the degree of anemia and leukocytic response in the affected cats.

Results and Discussion

On clinical examination, four cats were pyrexic, with body temperatures ranging from 103.5°F to 104.2°F, while all six cats showed varying degrees of dehydration, (Dakshinkar et al., 2002, Tarello, 2008) [7,16] indicated by prolonged skin tenting (>4 seconds). Pale mucous membranes were observed in three cats, suggesting anemia. Bilateral corneal cloudiness (Fig. [5,2] . and circling movement, were noted in several animals, indicating possible nervous system involvement. Microscopic examination of the Giemsa-stained blood smear revealed the presence of extracellular, flagellated trypomastigote forms of Trypanosoma evansi, confirming trypanosomiasis (Fig. 2 & 3). The organisms were characterized by an elongated body, a centrally placed nucleus, a posterior kinetoplast, and a free flagellum extending from the undulating membrane. The hematological analysis showed a marked decrease in total erythrocyte count (TEC), hb concenstration (Table .1), along with leukopenia. These findings are indicative of hemolytic anemia and bone marrow suppression, which are common hematological alterations observed in trypanosome infections (Da Silva et al., 2009a) [5] . The pathogenesis of trypanosomiasis in cats mentioned in biochemical findings ( [6] . Supportive therapy included isotonic fluid replacement to correct dehydration, vitamin Bcomplex supplementation, and hematinics to enhance erythropoiesis and overall recovery. Following initiation of therapy, noticeable clinical improvement was observed in all six cats within five days. Appetite and hydration status gradually normalized, body temperature returned to the physiological range, and the mucous membranes regained normal pink coloration. However, mild weakness persisted in a few animals for several days, indicating that complete hematological recovery required additional time. Although felines are generally regarded as relatively resistant hosts to Trypanosoma evansi infection, predisposing factors such as physiological stress, inadequate nutrition, or concurrent systemic diseases may compromise their immune response and lead to the clinical manifestation of trypanosomiasis.

Conclusion

Feline trypanosomiasis, although relatively uncommon, should be considered as a differential diagnosis in cats presenting with anemia, pyrexia, lymphadenopathy, or neurological signs, particularly in areas where the disease is endemic. The present report underscores the importance of thorough clinical assessment, coupled with wet blood film examination for the definitive identification of Trypanosoma evansi infection in cats. Prompt diagnosis and timely administration of Diminazene aceturate, along with appropriate supportive therapy, can result in favorable clinical outcomes. Increasing awareness among veterinary practitioners regarding the occurrence of trypanosomiasis in small animals is vital for early detection, effective management, and prevention of this potentially zoonotic disease.

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