|Year : 2001 | Volume
| Issue : 3 | Page : 116--118
Guest editorial the tragedy of tigers: Lessons to learn from nandankanan episode
SC Parija, S Bhattacharya
Department of Microbiology, JIPMER, Pondicherry - 605 006, India
S C Parija
Department of Microbiology, JIPMER, Pondicherry - 605 006
|How to cite this article:|
Parija S C, Bhattacharya S. Guest editorial the tragedy of tigers: Lessons to learn from nandankanan episode.Indian J Med Microbiol 2001;19:116-118
|How to cite this URL:|
Parija S C, Bhattacharya S. Guest editorial the tragedy of tigers: Lessons to learn from nandankanan episode. Indian J Med Microbiol [serial online] 2001 [cited 2013 May 22 ];19:116-118
Available from: http://www.ijmm.org/text.asp?2001/19/3/116/8143
The National Geographic Society estimates that 100,000 tigers roamed free on the earth at the turn of last century. However, the number was down to 5000 to 7000 when the 20th century ended. In other words about 93-95% of the world's tiger population has been decimated in the last 100 years. The major reason, which threatens the existence of the tigers, is indiscriminate poaching for hides, bones and nails. Apart from that, human encroachment into the tigers' habitat due to extensive deforestation have also taken its toll. But there are other issues which has escaped attention of most of us. It is the issue of tiger health. The dramatic decrease in the number of tigers coupled with their restriction to few national parks and zoological gardens have brought into focus the urgent need to understand the diseases afflicting the tigers. How we address the question concerning the diseases of tigers, their diagnosis, treatment and prevention will determine the fate of this remarkable animal. The death of 12 tigers in the summer of the year 2000, nearly a year back, at the Nandankanan zoo in Orissa poses some fundamental questions in relation to the epidemiology of the infectious diseases.
Between 23rd June 2000 and 7th July 2000, 12 tigers died at the Nandankanan. This zoo, which is near Bhubaneswar, the capital of Orissa, housed 56 tigers (32 white and 24 normal tigers). It had the largest collection of Royal Bengal tigers in India, and the world's largest collection of white tigers. The first death was reported on 23rd June . On July 5th, 9 more tigers (including 7 rare white tigers) died one by one. On July 6th, 6 tigers were under treatment at the zoo hospital, the condition of two of them were reported to be critical. By July 7th the number of dead tiger had risen to 12 (according to some reports ,13) the largest incident of disease related death of tigers in captivity in India.
The death of wildlife animals in captivity or in reserve forest is not an unusual phenomenon. Poaching, poor maintenance, lack of sanitary conditions, lack or deprivation of food and loss of habitat are some of the common reasons. However, the recent episode of tiger deaths at Nandankanan zoo has come as a shock to wildlife lovers, experts, veterinarians and microbiologists. This is not just because of the fact that the tiger is an endangered species and the death of 12 or 13 out of 56 is equivalent to a national loss. The death of these tigers have exposed the lacunae in the policy or guideline to handle a crisis of such magnitude, How to diagnose an unusual disease in wild animals, how to treat them and prevent spread to other members of the same species or others; are questions which have no satisfactory answers.
Non-human trypanosomiasis is not an uncommon disease. The species associated with non-human trypanosomiasis include Trypanosoma evansi (a species which infects camels in Africa, and water buffaloes, pigs, cattle sheep and goats in Asia), T. vivax (infects ruminants), T. equiperdum (infects horses where it is a sexually transmitted disease), T. theileri (occurs in India and infects mammals). The reduviid bug (Triatoma spp.) and tsetse flies (Glossina spp.) are the vectors involved in South American and African trypanosomiasis. Among the zoonotic species T. theileri is thought to be a non-tsetse trypanosomiasis in India, flies and ticks are suspected as mechanical vectors.,,
The primary clinical signs, which characterize trypanosomiasis in tigers, are intermittent fever, anemia, and weight loss. The incubation period of the disease ranges between 1-4 weeks. Based on the clinical findings like an anemic animal in poor condition, in an endemic area, a presumptive diagnosis of trypanosomiasis is made. The diagnosis is confirmed by demonstration of trypomastigotes in stained peripheral blood smear, or by the demonstration of the motile trypomatigotes in wet mounts of blood.4 Trypanosomiasis in tigers may be treated with bernyl or cymelarsan (0.75-1mg/kg). The safety of diminazine aceturate and quinapyramine sulphate has not yet been established. The choice of drug for treatment depends on the species of Trypanosoma. Drug resistance may occur and should be considered in cases refractory to treatment.
In the Nandankanan tiger tragedy, there seems to be at least four ways by which a tiger could have been infected with trypanosomes: first by the bite of a blood sucking insect from a local reservoir host (pigs, cattle, sheep, goat). Second, the bite of a blood sucking insect from an exotic animal species in the zoo. A few weeks before the tiger deaths, the zoo had exchanged 25 species of other animals and birds for 2 normal and 6 white tigers. Third, transmission by dirty needles used on infected African or American species. Immunisation against tuberculosis and rabies is routinely done in the zoo and use of same syringes to different animals is a common practice in such situations. Fourth, tigers might have been infected by ingestion of freshly cut meat from infected dead animals.
There is no second opinion for preserving the tiger populations. Apart from the ethical issue of equal right of every species and the aesthetic aspect of its beauty, there are scientific reasons to believe in protection of tigers. The tiger like any other species on this earth, constitutes an important part of the food chain keeping the number of herbivores in check. The extinction of tigers would not only jeopardize the food chain but also deal a blow to bio-diversity of our planet.
In the absence of an effective vaccine and realistic chemoprophylactic measures, alternative strategies need to be developed to prevent trypanosomiasis in tigers and other endangered wild animals. “Trypanotolerance” is one such concept, which is gaining ground. “Trypanotolerance” is defined as the relative capacity of an animal to control the development of parasites and to limit their pathological effects, the most prominent of which is anemia. Determination of the packed cell volume (PCV) and parasitaemia, are the two principal indicators of this phenomenon. Trypanotolerance can be induced through selective breeding.
The Amur tiger is being given protection in Russia through the creation of three tiger protective zones. These include the zone of “tiger bastion”, the zone of “stable compromise” (between, the interests of tiger conservation and economic development of the territory) and a “tiger free” zone, where the animals periodically migrate. A similar approach may be helpful for the conservation of the Royal Bengal Tigers. The use of Satellite imagery and remotely sensed meteorological data can be other hi-tech strategies to find out the spatial pattern of trypanosomiasis.,
The zoonotic trypanosomiasis in tigers (Pathera tigris) at Nandankanan has brought into sharp focus the lacunae of health administration and policy. Firstly, although a year has passed since the tragedy, much has to be done to prevent such incidents in future not just in tigers but also in other wild animals. Secondly, it is essential to formulate definite policy guidelines to manage such diseases in other wild animals in which such exotic diseases are likely to occur in future. Thirdly, there is no reason to believe that such exotic infections may not transmit from animals to man and may never occur in human beings. Non -tsetse trypanosomiasis in tigers in non -endemic regions has shown that there is nothing called “host specificity” with respect to parasitic infections. Given the right microenvironment and vehicle for transmission, species barrier can be broken by any parasite. The spread of prion diseases from cattle to humans in Great Britain and the outbreak of chicken influenza in humans at Hong Kong have only highlighted this possibility in relation to parasitic diseases. Trypanosomiasis, babesiosis, alveolar echinococcosis and onchocerciasis are some parasitic infections which till now have not been detected in India among humans.9 But in the age of jet air travel where any distance on the globe can be traversed in matter of hours, the concept of 'endemicity' and 'exotic infections' needs to be redefined. This calls for a close interaction and partnership between veterinarians, entomologists, and medical microbiologists.
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