Co-Infection and Wild Animal Health: Effects of Trypanosomatids and Gastrointestinal Parasites on Coatis of the Brazilian Pantanal

Abstract

Wild animals are infected by diverse parasites, but how they influence host health is poorly understood. We examined the relationship of trypanosomatids and gastrointestinal parasites with health of wild brown-nosed coatis (Nasua nasua) from the Brazilian Pantanal. We used coati body condition and hematological parameters as response variables in linear models that were compared using an information theoretic approach. Predictors were high/low parasitemias by Trypanosoma cruzi and T. evansi, and indices representing the abundance of distinct groups of gastrointestinal parasites. We also analyzed how host health changed with host sex and reproductive seasonality. Hemoparasites was best related to coati body condition and hematological indices, whereas abundance of gastrointestinal parasites was relatively less associated with coati health. Additionally, some associations were best predicted by models that incorporated reproductive seasonality and host sex. Overall, we observed a lower health condition during the breeding season, when coatis are under reproductive stress and may be less able to handle infection. In addition, females seem to handle infection better than males. Body condition was lower in coatis with high parasitemias of T. evansi, especially during the reproductive season. Total red blood cell counts, packed cell volume, platelets and eosinophils were also lower in animals with high T. evansi parasitemias. Total white blood cell counts and mature neutrophils were lower in animals with high parasitemias for both Trypanosoma species, with neutrophils decreasing mainly during the reproductive season. Overall, decreases in hematological parameters of females with T. evansi high parasitemias were less evident. For T. cruzi, monocytes decreased in individuals with high parasitemias. High abundances of microfilariae in the bloodstream, and cestode eggs and coccidian oocysts in feces were also associated with coati blood parameters. This study shows the potential value of examining hematological parameters as an approach to better understand the ecological relevance of parasite-host interactions.

Variation in the prevalence and abundance of acanthocephalans in brown-nosed coatis Nasua nasua and crab-eating foxes Cerdocyon thous in the Brazilian Pantanal

“…Indeed, model analysis for abundance of acanthocephalan eggs in coatis indicated that host sex was an important predictor of infection; male coatis seem to be more affected by parasitism, especially during the breeding season, which may in turn favor higher parasite intensities. Olifiers et al (2015) found similar results for Trypanosoma evansi infection in coatis from the same study site.…”

Biochemical and physiological parameters associated withTrypanosomaevansiprevalence in wild capybaras (Hydrochoerushydrochaeris)

“…Finally, Olifiers et al (2015) reported that body condition was lower in wild coatis (Nasua nasua) with high parasitemia of T. evansi than those which tested negative, especially during the reproductive season. This is in agreement with our observations, but it should be taken into account that our cross-sectional results cannot distinguish cause from effect (i.e.…”

“…There is experimental evidence in mice, rats, dogs, donkeys, horses and coatis that T. evansi cause anemia following the first wave of parasitemia (Aquino et al 2002;Herrera et al 2002). In dogs, horses and freeliving animals such as coati, lower red blood cell counts (RBC) were reported in animals with high parasitemia (Herrera et al 2004;Olifiers et al 2015). Similarly, capybaras infected with T. evansi showed lower mean RBC counts than those not infected animals, however this difference was not significant (p = 0.063).…”

“…Previous results on leukocytes and counts of each cell type, both in naturally and experimentally infected mammal hosts, have been varied. For example, Olifiers et al (2015) reported that coatis naturally infected by T. evansi also showed a reduced number of eosinophils and neutrophils; dogs showed a decrease in circulating leukocyte counts during infection (Aquino et al 2002), while cats, horses and guinea pigs exhibited an increase (Monzón et al 1991;Silva et al 2010). Our results suggest a cellular immunological debilitation (since all leukocyte populations tended to be lower in infected individuals) at the expense of antibody production (infected capybaras showed higher levels of gamma-globulins than those not infected, see above).…”

“…Although infections by T. evansi have been reported in many South American wild hosts, only in coatis it has been found to cause a measurable impact on the host's health, i.e. anemia, emaciation and immune suppression (Herrera et al 2004;Olifiers et al 2015). In infected capybaras, there is no evidence of pathological effects despite high levels of parasitemia, suggesting that this host species could act as a reservoir for T. evansi in the region (Franke et al 1994;Arias et al 1997;Herrera et al 2004).…”