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Accueil du site → Doctorat → Allemagne → 2016 → Serological and microbiological evaluation of the health status of free-ranging and captive cheetahs (Acinonyx jubatus) on Namibian farmland

Freie Universität Berlin (2016)

Serological and microbiological evaluation of the health status of free-ranging and captive cheetahs (Acinonyx jubatus) on Namibian farmland

Weigold, Annika

Titre : Serological and microbiological evaluation of the health status of free-ranging and captive cheetahs (Acinonyx jubatus) on Namibian farmland

Serologische und mikrobiologische Untersuchungen zum Gesundheitsstatus von freilebenden und in menschlicher Obhut gehaltenen Geparden (Acinonyx jubatus) auf namibischem Farmland

Auteur : Weigold, Annika

Université de soutenance : Freie Universität Berlin

Grade : Doktors der Veterinärmedizin 2016

Résumé
The largest free-ranging population of cheetahs, classified as vulnerable, currently lives on Namibian farmland. For this thesis, free-ranging cheetahs were captured, examined, sampled and radio-collared, and captive cheetahs held in large enclosures were examined and sampled. With these collected samples and data, as well as previously collected ones, I performed the tests and analyses included in this thesis. The aims of this thesis were to examine the health status of the Namibian cheetahs and to analyse blood samples serologically and microbiologically. Firstly, the serological tests followed on from a previous study that detected the first seropositive results for antibodies against feline leukemia virus (FeLV), a gammaretrovirus, in free-ranging cheetahs. For this I used various molecular tests as well as cell cultures. Secondly, I evaluated the immune response to FeLV vaccinations in captive cheetahs. Finally, I describe the first evidence of a hitherto unrecognized species of hemoplasma in cheetahs. In the appendix, I present a study in which I collaborated on the development and validation of an enzyme immunoassay to measure the metabolites of testosterone in faecal samples of cheetahs. Viral infections pose worldwide a significant threat to free-ranging and captive held wildlife species. Prominent examples are the fatal outbreaks of FeLV infections reported in freeranging Iberian lynxes (Lynx pardinus) and in captive cheetahs. Thus, it was of high importance to follow up on a previous study providing the first evidence that Namibian freeranging cheetahs came into contact with gammaretroviruses. In my study, I conducted numerous analyses and measured, depending on the test used, in up to 19% of free-ranging cheetahs antibodies against FeLV or a closely related gammaretrovirus. Seropositive animals were also seropositive for the Rauscher murine leukemia virus. Yet, no proviral DNA was detected. The seropositive, clinically healthy cheetahs might have been infected with a weakly pathogenic retrovirus or turned seropositive due to the expression of an endogenous retroviral sequence. Thus, the gammaretrovirus does not seem to pose currently a risk to the health of the cheetah population. The cheetahs held in enclosures had been vaccinated yearly for several years with a FeLV vaccine developed for the use in domestic cats. Antibody formation was measured in 86% of the captive cheetahs and no animal developed any notable adverse reactions. Thus, this vaccine might be a useful protection for cheetahs. However, vaccinations in free-ranging animals should only be used after very careful risk-benefit analyses and after extensive laboratory tests under controlled conditions. Infections with hemoplasmas, cell wall-free bacteria that parasitize red blood cells, have been described in many free-ranging and domestic animals and can cause feline infectious anemia in cats. Particularly in immunocompromised animals the effects of a hemoplasma infection can be life threatening. Until now there was no description of hemoplasma in any free-ranging feline species in southern Africa. My case study thus represents a first description. This is, however, not only the first report of an infection of a free-ranging Namibian cheetah with hemoplasma, but also a newly described isolate assigned to the Mycoplasma haemofelis/haemocanis group after the sequencing of the 16S rRNA and the RNAse P genes. The clinical implications and the mode of transmission of this disease remain unknown, but the infected cheetah did not show any signs of health impairment upon examination and was localised alive via radio collar for another 48 months. Hence, studies on serological and microbiological surveys are important for the assessment of the health status of a free-ranging population and are also relevant in the development of management to reduce human-animal conflicts. Concerning the latter, translocations of carnivores are performed regularly, yet without the evaluation of risks of infections in the new or also the old habitats. It would be advisable to routinely perform such surveys to eliminate the risk of disseminating pathogens during translocations. Comparative serological studies of free-ranging populations and captive held animals are very promising and should be continued. Only with sufficient science based information can we plan the urgently needed long-term strategies for further management of endangered carnivores and react on potential future epidemics

Mots clés  : Acinonyx jubatus ; ELISA ; Feline leukemia virus ; blood serum ; microbiology ; immune response ; populations ; health ; vaccination

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Page publiée le 2 novembre 2017, mise à jour le 28 décembre 2018