Successful management of Trypanosoma spp. in a royal Bengal tigress (Panthera tigris tigris)

Introduction

Natural infections of T. evansi have been reported in 48 countries, including 20 in Asia, 17 in Africa, seven in South America, and four in Europe, with no reports in North America, Australia, or Antarctica. Since surra was classified as an OIE notifiable disease in 2009, 27 countries have confirmed its presence at least once (Aregawi et al., 2019) [2] . Surra originated in Africa, where T. evansi evolved from T. brucei brucei through partial or complete loss of kinetoplastic DNA (Lun et al., 1995; Lai et al., 2008) [18,17] . In Asia, numerous outbreaks linked to high morbidity and mortality have been recorded in Timor rusa deer (Rusa timorensis) and hog deer (Axis porcinus). Clinical cases and fatalities due to surra have also been observed in endangered species, including the Asian black bear (Ursus thibetanus), Asian elephant (Elephas maximus), leopard (Panthera pardus), tigers (Panthera tigris), jaguar (Panthera onca), and Sumatran rhinoceros (Dicerorhinus sumatrensis) (More et al., 2017) [19] . An outbreak of T. evansi in circus tigers was reported by Bhaskararao et al. (1995) [4] , following the feeding of infected meat. The prevalence of T. evansi in wild ruminants and the potential for oral transmission to wild carnivores, particularly endangered species, constitutes a significant threat (Herrera et al., 2011) [11] . Tigers are unique animals that play a critical role in maintaining ecosystem balance. According to IUCN, approximately 3,900 tigers remain in the wild, with 2,967 found in India-accounting for about 80% of the global tiger population. Their habitat is restricted to a few national parks and zoological gardens. Various health-related issues hinder population maintenance, emphasizing the need to understand diseases affecting tiger health (Deka et al., 2021) [7] . Trypanosomiasis (surra), caused by T. evansi, is a significant disease, transmitted mechanically through the bites of blood-sucking flies, including tabanids (Tabanus, Haematopota, Haematobia). The rainy and post-rainy seasons are particularly conducive to the development of tabanid larvae, increasing disease propagation during these times. H o w e v e r , c a s e s o f s u r r a c a n o c c u r y e a r -r o u n d . D e s p i t e i t s w i d e distribution, current information on the prevalence and economic impact of feline trypanosomosis in India remains limited.

Recently, it has emerged in non-endemic areas, infecting new hosts and raising concerns about its zoonotic potential, including occasional human infections (Joshi et al., 2005; Powar et al., 2006) [12,24] . The spillover of parasites from wildlife to domestic livestock and humans, and vice versa, compromises health (Thompson, 2013) [28] . While most trypanosome infections in wildlife do not cause significant harm to their hosts (Auty, 2012) [3] . However, there is a high risk of infection spillover from game parks and conservation areas where parasites and vectors are concentrated in high numbers, and domestic livestock pose risks to wildlife-protected species. The foundation of trypanotolerance in wildlife species remains inadequately comprehended. The extensive genetic variety of Trypanosoma spp. poses a difficulty by heightening the likelihood of enhanced virulence (Kasozi et al., 2021) [15] Clinical Observation and Treatment A 3-year-old female tigress exhibited signs of lethargy, persistent yawning, and loose feces during the monsoon season. She was placed in a treatment cage for further evaluation, which indicated a high-grade fever of 104.5°F, hyperemia of the vaginal and anal mucous membranes, and mild rectal bleeding. Blood samples were collected via venipuncture of the coccygeal vein. The results of hematology and serum biochemistry are detailed in Table No

Discussion

Felids in their natural environments typically traverse large territories, leading to lower parasitic exposure and, consequently, lower genetic resistance to such infections (Raja et al., 2014) [25] . In captivity, especially in zoological settings, the prevalence of parasitic infections can increase significantly, creating a serious threat (Muoria et al., 2005) [21] . Parasitic infections not only contribute to morbidity in these animals but can also lead to fatal outcomes in severe cases (Chhabra and Pathak, 2013) [5] . Trypanosoma evansi has diverse origins, host species, and clinical manifestations.

T. evansi was reported natural infections in four Himalayan charming bears, in Pakistan; the animals exhibited high fever, anaemia, high pulse and respiration rate, tachypnoea, ataxia and depression (Muhammad et al., 2007) [20] .

Elephants are affected the same as camel. Affected elephants show pyrexia, anaemia, loss of appetite, oedema of the face, neck, brisket, trunk, limbs and lower abdomen, dry and hard skin, restlessness, reluctance to work, dullness, listlessness and sleepy appearance. Urine is scanty and progressively becomes viscous and sometimes marked greenish in colour. Swelling between the jaws and the lower part of the abdomen is often seen (Desquesnes et al., 2013) [8] . Clinical signs in affected tiger intermittent temperature (102-105°F), anorexia, lacrimation and pale mucous membrane, enlargement of prescapular lymph node, nervous signs like seizures, uncontrolled movements in the body and sometimes a transitory change in consciousness (Khan et al., 2015) [16] . In the present case, the tiger showed signs of lethargy, loose faeces and high fever.

Its transmission occurs through various means, such as biting and sucking insects, vampire bats, as well as vertical, horizontal, iatrogenic, and oral routes, with different epidemiological significance based on season, location, and host species. Leeches may also transmit trypanosomes, a factor worth examining, particularly in relation to the buffalo leech (Hirudinaria manillensis) in Asia (Desquesnes et al., 2013) [8] . Blood glucose level of donkeys with surra fluctuates with initial transient hyperglycaemia and later persistent hypoglycaemia that extends to chronic stage of T.

evansi infection. Acute injury to pancreas might have reduced insulin activity to control blood glucose level (Sun et al., 2016) [27] . Host glucose reserve is increasingly utilized and depleted by host animal body cells in febrile condition (Habila et al., 2012) [10] blood stream form trypanosome, trypomastigote and in presence of hepatocytes degeneration in trypanosomosis due to increased demand for metabolism resulting in hypoglycemia (Garba and Mayaki, 2018) [9] . Quinapyramine, part of the amino quinaldine derivatives, can be administered as quinapyramine methyl-sulphate through subcutaneous injection at a dosage of 5 mg/kg body weight to treat infections. A more effective combination, quinapyramine sulfate and quinapyramine chloride (Triquin), can be used as a therapeutic and preventive measure against T. evansi in horses and camel. While local tolerance may be low, the drug is generally effective, offering chemoprophylactic effects for up to four months (Desquesnes et al., 2013) [8] . Control primarily relies on chemotherapy, yet this approach presents challenges, including high costs and limited drug availability. Diminazene and quinapyramine are the primary agents used in India, with most trials focusing on these two. Other effective drugs face supply issues, like suramin, and cymelarsan has yet to receive commercial approval. Singh and Joshi (1991) [26] evaluated diminazene, suramin, quinapyramine, and isometamidium in naturally infected buffaloes, finding both quinapyramine (4.4 mg/kg body weight) and isometamidium (0.5 mg/kg body weight) effective therapeutically, while quinapyramine proved superior for prophylaxis. A subsequent study (Joshi and Singh, 2000) [13] confirmed all four drugs were therapeutically effective against clinical T. evansi i n buffaloes, but their prophylactic efficacy varied: quinapyramine (66.6%), suramin (66.6%), isometamidium (33.3%), and diminazene (0%). Improvements in haemoglobin, PCV, and TEC values, along with significant increases in blood glucose, total serum protein, and cholesterol, were noted post-treatment (Joshi and Singh 2001) [14] . In camels, quinapyramine pro-salt proved effective as both a therapeutic and prophylactic agent against natural T. evansi infections (Pathak et al., 1997a) [23] .

A case in Andhra reported successful treatment of a goat infected with T. evansi using quinapyramine chloride (Rao and Hafeez, 1999) [4] . De and Mukherjee (2006) [6] successfully managed trypanosomiasis in a 2-year-old male horse with quinapyramine sulfate. Muraleedharan (2015) [22] noted that diminazene diaceturate and Antrycide curative are common treatments for trypanosomiasis in livestock and tigers. Ananda et al. (2014) [1] reported clinical cures in trypanosome-positive cases treated with Triquin along with supportive therapy.

Acknowledgement

AcknowledgementsThe authors are thankful to Hon'ble PCCF (WL) and Chief Wildlife Warden, Maharashtra State, the FDCM Pvt. Ltd and Divisional Manager, Gorewada Project, Nagpur for granting permission to manage the Trypanosomiasis in a Female Tiger at Wildlife Research and Training Centre, Nagpur and also for providing the facilities required for its successful management.

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