| Infectious diseases can be significant threats to public health (Binder et al., 1999; Smith et al., 2009), and in the last decades, there have been a number of outbreaks of new pathogens in humans, with more than 70% coming from wildlife (Jones et al., 2008). Parasites can have important effects on wildlife as well, affecting individuals, populations, communities and even entire ecosystems (Hudson et al. , 2002; Smith et al., 2009). For instance, parasites may decrease health of their hosts, regulate population numbers and contribute to local extinctions (Anderson & May, 1978; May & Anderson, 1978; Scott & Dobson, 1989; Dobson & Hudson, 1992; Hudson et al. , 1998). Yet, despite their role in several levels of life organization, there is still a relatively poor understanding of the impact parasites have on the health and demography of wild hosts. This is not only a reflection of a superficial knowledge about basic ecology of wild hosts and their parasites, but also a lack of attention to critical questions linking ecology and parasitology.;The paucity of studies on the brown-nosed coati (Nasua nasua : Linnaeus, 1766) and the crab-eating fox (Cerdocyon thous ; Linnaeus, 1766) exemplifies how we still know little about the interplay between wild hosts and their parasites. These carnivores are very abundant and widespread in South America and they harbor several parasites that infect wildlife, domestic animals, and humans (Ferriolli & Barreto, 1968; Miles et al., 1983; Lainson et al., 1989; Nunes & Oshiro, 1990; Oshiro et al., 1990; Nunes et al., 1993; Gompper & Decker, 1998; Courtenay & Maffei, 2004). Despite this, little is known about the life-history of these carnivores, the dynamic of their parasites, and how parasites affect host health. Coatis, for example, have been suggested as important reservoirs of Trypanosoma cruzi and T. evansi (Kinetoplastida: Trypanosomatidae) in the Brazilian Pantanal wetlands (Herrera et al., 2004; Herrera et al., 2008). These protozoans are of health and economic importance since they cause Chagas disease in humans and "Mal de Cadeiras" disease in horses, respectively. The effect of trypanosomatids on the coati health and the potential effect of these parasites on the population dynamics of coatis are, however, only superficially known (Silva et al., 1999; Herrera et al., 2001; Herrera et al., 2002; Alves et al., 2010).;Understanding the effects of parasites on hosts requires not only knowledge about the parasites themselves, but also about the ecology of their hosts. This dissertation was developed with this aim in mind. It is part of a larger collaborative effort with a diverse group of researchers examining the population biology and disease ecology of several species of midsized carnivores, and the epidemiology of parasites of public health concern in the Pantanal region, Brazil. The dissertation is divided in four chapters: the first and second chapters regard, respectively, the development of a tool for aging coatis and crab-eating foxes and the collection of basic information on the life-history of these species in the study area. Information gathered in these two chapters was then used in the following sections. In the third chapter, I focus on ectoparasites of coatis and foxes, particularly on ticks. I investigate how abiotic factors and the host attributes described in chapters 1 and 2 influence tick abundance and prevalence on hosts. This chapter can be considered a model for investigating the relative importance of biotic and abiotic factors in parasite dynamics. Finally, in chapter 4 I focus on how hemoparasites and gastrointestinal parasites affect coati health. There are few studies which have investigated the 3 effects of multiple parasites on direct measures of the health parameters of free-ranging hosts. In this sense, this last chapter can also be viewed as a model for future studies focusing in the interplay between parasites and health of wild, free-ranging mammals.;For a better picture of the broader project, additional publications from this collaborative effort should be referred. In these, the reader will find additional information regarding the behavior of coatis and foxes (Bianchi, 2009; Olifiers et al., 2009), their ectoparasites (Cancado, 2008), and the dynamics of T. cruzi and T. evansi in coatis from the Pantanal (Herrera et al., 2008; Alves et al. 2010). |
