Diseases can have a range of impacts on hosts and host populations. These impacts can be minimal, to the point of being considered nearly a commensal relationship. The other end of the spectrum is when a disease regulates a population or even drives it to extinction. Diseases that are directly transmitted in a density-dependent manner typically do not cause population extinction because as the population decreases so does transmission. However, there are several factors that can lead to extinction caused by diseases. These diseases can be frequency-dependent transmission (including vector-borne diseases) or diseases that infect multiple sympatric hosts. The parasite Cytauxzoon felis is a tick-borne apicomplexan that infects bobcats and domestic cats and is enzootic in the Midwest and Southeast US. Bobcats are considered the reservoir host of C. felis and typically do not show signs of disease associated with infection. This parasite is the etiological agent of cytauxzoonosis, a highly-fatal disease impacting domestic cats and occasionally other felid species. Domestic cats also can be subclinically infected. This parasite has increased its range and density within previously described enzootic areas. There are several aspects of the biology of C. felis that have not been explored and impact the epizootiology of this important veterinary parasite. The prevalence of the parasite has been studied in some locations, yet areas where the parasite has recently invaded need to be studied as populations of naïve bobcats and domestic cats may be at risk of epizootics. My research expands the knowledge of C. felis, adding information about a relatively recently-described enzootic area. The present dissertation is divided into 6 chapters. In the first chapter I provide a thorough literature review of C. felis and general information on pathogens. In my second chapter I describe the prevalence of C. felis in bobcats and ticks in southern Illinois from 2006-2017. This is the first documentation of C. felis in bobcats in Illinois. The prevalence in ticks is also the highest prevalence in ticks reported to date. These results have been published in the Journal of Parasitology. In the third chapter I provide evidence of chronic C. felis infections in bobcats. Some bobcats maintained C. felis infection for at least 2 years. I determined individual bobcats were infected with the same strain of the parasite at each capture event. This finding indicates that bobcats may carry the same strain over time. These infected bobcats could be spreading strains that are more pathogenic to domestic cats and possibly to other bobcats. Vector-borne pathogens (specifically microparasites) can show varying levels of intensity of infection in vertebrate hosts. The intensity of infection may correlate with activity of the vectors to facilitate transmission from the vertebrate to the vector. In the fourth chapter I tested if C. felis parasitemia (percent of red blood cells infected with the parasites) increased with environmental factors associated with tick activity. Cytauxzoon felis infections are increasing in domestic cats in the US in many areas. The fifth chapter describes the first study of clinical and subclinical C. felis infections in domestic cats in southern Illinois. I collaborated with veterinary clinics to obtain 642 domestic cat blood samples for this project. I also tested whether land cover types and host characteristics were related to risk of infection, and found only that feral cats were more likely to have subclinical C. felis infection. Cytauxzoon felis is transmitted through a tick vector; so direct contact between domestic cats and bobcats is not necessary for transmission to occur. For the sixth chapter I tested if the genetic populations of C. felis in domestic cats and bobcats were different (suggesting barriers to transmission). I found that there was high genetic diversity of C. felis in my samples. The within population variance accounted for nearly all variance detected. Therefore I conclude that the population of C. felis in bobcats and domestic cats in my study area is panmictic suggesting there are no barriers to transmission between these two host species.

Made available in DSpace on 2014-06-11T19:23:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-01-20Bitstream added on 2014-06-13T19:30:25Z : No. of bitstreams: 1 metzger_b_me_botfmvz.pdf: 819148 bytes, checksum: 26a92a8f8879a45e826beca01ff7b6a5 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O trabalho teve como objetivo investigar a ocorrência de Hepatozoon spp., piroplasmas e hemoplasmas em felídeos neotropicais nascidos em vida livre. Amostras sanguíneas foram colhidas de 11 Leopardus pardalis, 10 Leopardus tigrinus, oito Puma yagouaroundi, um Leopardus wiedii e um Puma concolor, provenientes dos Estados do Pará, Maranhão, Piauí, Ceará e Minas Gerais. Esfregaços sangüíneos foram realizados para observação dos hemoparasitas e a extração de DNA foi feita para utilização em técnicas moleculares. Hepatozoon spp. e piroplasmas foram diagnosticados pela Reação em Cadeia de Polimerase (PCR) e hemoplasmas felinos foram pesquisados pela PCR- RFLP e “Nested”-PCR. A caracterização molecular dos isolados obtidos foi feita após o sequenciamento e a análise filogenética. A ocorrência de pelo menos um hemoparasita diagnosticado pela técnica do esfregaço sanguíneo foi de 6,45% (2/31) e pela PCR foi de 45,16% (14/31), sendo observadas, 16,12% (5/31), 3,22% (1/31) e 38,70% (12/31) de infecções por Hepatozoon sp., Cytauxzoon felis e hemoplasmas (das espécies Mycoplasma haemofelis e/ou Candidatus Mycoplasma haemominutum), respectivamente. Foram encontradas infecções únicas e mistas nos felídeos. O diagnóstico positivo foi maior nos adultos (92,85%) (p=0,007) e na espécie L. pardalis (57,14% - 8/14). A detecção de C. felis em exemplar juvenil de P. concolor, recém capturado na natureza, indica sua presença na população de felídeos neotropicais de vida livre no Brasil. A caracterização molecular de Hepatozoon sp. em felídeos neotropicais e os relatos das infecções por este hemoparasita em L. tigrinus e por M. haemofelis e Candidatus M. haemominutum em P. yagouaroundi são inéditos no mundo. / The aim of this study was to investigate the occurrence of Hepatozoon spp., piroplasms and hemoplasms in wild caught neotropical felids. Blood samples were drawn from 11 Leopardus pardalis, 10 Leopardus tigrinus, eight Puma yagouaroundi, one Leopardus wiedii and one Puma concolor coming from the States of Para, Maranhão, Piauí, Ceará and Minas Gerais. Blood smears were evaluated for parasites and DNA was extracted for molecular techniques. Hepatozoon spp. and piroplasms were diagnosed by Polymerase Chain Reaction (PCR) and feline hemoplasms were examined by both RFLP-PCR and Nested- PCR. Molecular characterization of the isolates obtained was performed after sequencing and phylogenetic analyses. The occurrence of at least one hemoparasite diagnosed by blood smear technique was 6.45% (2/31) and by PCR was 45.16% (14/31). Infections of Hepatozoon sp., Cytauxzoon felis and feline hemoplasms (from species Mycoplasma haemofelis and/or Candidatus Mycoplasma haemominutum) were observed, respectively, in 16.12% (5/31), 3.22% (1/31) and 38.70% (12/31) from the total of animals studied. Infections and co-infections were found among felids. The positive diagnosis were higher in adults (92.85%) (p= 0,007) and in L. pardalis (57.14% - 8/14). The detection of C. felis in a juvenile, recently wild caught P. concolor, indicates the presence of this piroplasm in the wild felid population of Brazil. The molecular characterization of Hepatozoon sp. in neotropical felids and the report of this hemoparasite infection in L. tigrinus as well as the report of M. haemofelis and Candidatus M. haemominutum in P. yagouaroundi are novelties in the world.

Orientador: Lucia Helena O'Dwyer de Oliveira / Banca: Katia Denise Saraiva Bresciani / Banca: Alessandro Francisco Talamini do Amarante / Resumo: O trabalho teve como objetivo investigar a ocorrência de Hepatozoon spp., piroplasmas e hemoplasmas em felídeos neotropicais nascidos em vida livre. Amostras sanguíneas foram colhidas de 11 Leopardus pardalis, 10 Leopardus tigrinus, oito Puma yagouaroundi, um Leopardus wiedii e um Puma concolor, provenientes dos Estados do Pará, Maranhão, Piauí, Ceará e Minas Gerais. Esfregaços sangüíneos foram realizados para observação dos hemoparasitas e a extração de DNA foi feita para utilização em técnicas moleculares. Hepatozoon spp. e piroplasmas foram diagnosticados pela Reação em Cadeia de Polimerase (PCR) e hemoplasmas felinos foram pesquisados pela PCR- RFLP e "Nested"-PCR. A caracterização molecular dos isolados obtidos foi feita após o sequenciamento e a análise filogenética. A ocorrência de pelo menos um hemoparasita diagnosticado pela técnica do esfregaço sanguíneo foi de 6,45% (2/31) e pela PCR foi de 45,16% (14/31), sendo observadas, 16,12% (5/31), 3,22% (1/31) e 38,70% (12/31) de infecções por Hepatozoon sp., Cytauxzoon felis e hemoplasmas (das espécies Mycoplasma haemofelis e/ou "Candidatus Mycoplasma haemominutum"), respectivamente. Foram encontradas infecções únicas e mistas nos felídeos. O diagnóstico positivo foi maior nos adultos (92,85%) (p=0,007) e na espécie L. pardalis (57,14% - 8/14). A detecção de C. felis em exemplar juvenil de P. concolor, recém capturado na natureza, indica sua presença na população de felídeos neotropicais de vida livre no Brasil. A caracterização molecular de Hepatozoon sp. em felídeos neotropicais e os relatos das infecções por este hemoparasita em L. tigrinus e por M. haemofelis e "Candidatus M. haemominutum" em P. yagouaroundi são inéditos no mundo. / Abstract: The aim of this study was to investigate the occurrence of Hepatozoon spp., piroplasms and hemoplasms in wild caught neotropical felids. Blood samples were drawn from 11 Leopardus pardalis, 10 Leopardus tigrinus, eight Puma yagouaroundi, one Leopardus wiedii and one Puma concolor coming from the States of Para, Maranhão, Piauí, Ceará and Minas Gerais. Blood smears were evaluated for parasites and DNA was extracted for molecular techniques. Hepatozoon spp. and piroplasms were diagnosed by Polymerase Chain Reaction (PCR) and feline hemoplasms were examined by both RFLP-PCR and Nested- PCR. Molecular characterization of the isolates obtained was performed after sequencing and phylogenetic analyses. The occurrence of at least one hemoparasite diagnosed by blood smear technique was 6.45% (2/31) and by PCR was 45.16% (14/31). Infections of Hepatozoon sp., Cytauxzoon felis and feline hemoplasms (from species Mycoplasma haemofelis and/or "Candidatus Mycoplasma haemominutum") were observed, respectively, in 16.12% (5/31), 3.22% (1/31) and 38.70% (12/31) from the total of animals studied. Infections and co-infections were found among felids. The positive diagnosis were higher in adults (92.85%) (p= 0,007) and in L. pardalis (57.14% - 8/14). The detection of C. felis in a juvenile, recently wild caught P. concolor, indicates the presence of this piroplasm in the wild felid population of Brazil. The molecular characterization of Hepatozoon sp. in neotropical felids and the report of this hemoparasite infection in L. tigrinus as well as the report of M. haemofelis and "Candidatus M. haemominutum" in P. yagouaroundi are novelties in the world. / Mestre