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Hot Damn Duo Group

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Luke Thompson
Luke Thompson

Parasite In City PATCHED

Background: Urbanization can strongly impact the physiology, behavior, and fitness of animals. Conditions in cities may also promote the transmission and success of animal parasites and pathogens. However, to date, no studies have examined variation in the prevalence or severity of several distinct pathogens/parasites along a gradient of urbanization in animals or if these infections increase physiological stress in urban populations.

parasite in city

Methodology/principal findings: Here, we measured the prevalence and severity of infection with intestinal coccidians (Isospora sp.) and the canarypox virus (Avipoxvirus) along an urban-to-rural gradient in wild male house finches (Haemorhous mexicanus). In addition, we quantified an important stress indicator in animals (oxidative stress) and several axes of urbanization, including human population density and land-use patterns within a 1 km radius of each trapping site. Prevalence of poxvirus infection and severity of coccidial infection were significantly associated with the degree of urbanization, with an increase of infection in more urban areas. The degrees of infection by the two parasites were not correlated along the urban-rural gradient. Finally, levels of oxidative damage in plasma were not associated with infection or with urbanization metrics.

Conclusion/significance: These results indicate that the physical presence of humans in cities and the associated altered urban landscape characteristics are associated with increased infections with both a virus and a gastrointestinal parasite in this common songbird resident of North American cities. Though we failed to find elevations in urban- or parasite/pathogen-mediated oxidative stress, humans may facilitate infections in these birds via bird feeders (i.e. horizontal disease transmission due to unsanitary surfaces and/or elevations in host population densities) and/or via elevations in other forms of physiological stress (e.g. corticosterone, nutritional).

We systematically reviewed the published scientific literature on the bat fauna found in urban areas of Brazil in order to provide a comprehensive analysis of ecological and epidemiological aspects of these mammals in disturbed areas. Therefore, we (1) appraised the bat species records throughout Brazilian cities to present an updated urban species list; (2) investigated the roosts and food sources to shed light on the factors implicated in their maintenance on urban environments and (3) reviewed the state of knowledge of urban bat parasites to assess their potential to become a public health hazard. The strengths and limitations of the existing research knowledge are also discussed.

We found 27 bat species (32% of the species) diagnosed at least once as hosts of 11 zoonotic parasites: rabies virus, Alphacoronavirus, bacteria of the genus Leptospira, protozoans of the genus Leishmania and Trypanosoma, and fungi of the genus Candida, Coccidioides, Histoplasma and Pneumocystis (Table 1). The most commonly studied parasite was the rabies virus, comprising about 75% of the records while the others were represented by only nine studies, most of them published in the last five years. Among the 36 parasitological studies, 27 discussed the relevance of bats in the transmission cycles of rabies virus and two others related bats with the transmission of Candida spp. and Coccidioides posadasii. The other seven studies, only reported the presence or absence of these parasites in bats.

In Brazil, the information regarding the urban bat fauna has expressively increased in the last ten years, indicating a growing interest in urban ecosystems by researchers. Yet, we demonstrated that the information on bats in urban environments is still incipient and spatially clustered in Brazil. Herein, based on our assembled list of 84 urban bat species, we discuss their diversity patterns and the determinants of its occurrence within Brazilian urban environments, in order to assess knowledge gaps and provide a current panorama for future bat researches. We found that 31 bat species were represented only in forest fragments within the urban matrix, while ten species were found exclusively inside man-made structures. Then, we present the wide variety of sites described as their day roosts and plants used as food resources in urban landscapes. The positives and negatives consequences of the human-bat interactions caused by the existing proximity in cities are also part of our discussion. We list eleven zoonotic parasites found infecting 27 bat species attempting to clarify their real potential impact on public health and highlight the necessity to also investigate health threats on bats. Finally, we raise several fundamental questions that remain unanswered aiming to define a research agenda for bat studies in urban areas of Brazil. The types of research needed to understand the impact of urbanization on bat diversity and conservation are also considered in this section.

The urban bat fauna herein presented, characterized by 84 species, represents 47% of the bat richness found in Brazil (Nogueira et al. 2014). Compared to recent compilations (Lima 2008; Pacheco et al. 2010), we added one family (Mormoopidae) and 19 species to the list of Brazilian urban bats. Eight of these new records are posterior to those reviews, whereas eleven of them had gone unnoticed or were not exactly in the scope of these studies. The state of Rio de Janeiro, one of the states with more sampled cities, is where five of 19 new species records were made. Thus, even in the area with the highest concentration of studies, there is still the need to continue the efforts and monitor bat communities to evaluate the urbanization effects in these mammals. Although these areas present a high number of studies, they are mainly composed by occurrence records, and there are few long-term studies on the ecology of bats in urban areas (e.g. diet, reproduction, competition or predation). Only ecological studies will allow to quantify the impacts of urbanization on individual, populations, species and bat communities. Also, the new record of eight species can be attributed to fieldwork conducted in poorly sampled areas (states with only one study and/or one city sampled). Consequently, we suggest that the list of Brazilian urban bat species would significantly grow with the increase in studies.

Besides the unequal distribution of studies, the capture methods are also another important bias given that the studies that used mist-nets as a sampling protocol were restricted to samples at the ground level, which is a selective technique and tends to misrepresent insectivorous bats (Voss and Emmons 1996; Simmons and Voss 1998). The use of understory and canopy nets in forested areas and active searches for shelters improves the capture probability of different bat families/species and thus, are essential for a more complete bat survey (Ferreira et al. 2013; Nunes et al. 2013; Vilar et al. 2015). Moreover, we lack bat diversity estimators for the majority of urbanized areas, due to inappropriate sampling designs. For phyllostomid bats, the minimum sampling effort suggested is of 1000 mist net captures at a given site (Bergallo et al. 2003). Among the bat surveys based on field work which provided abundance data, we found that 63% sampled less than 500 bats. Only two studies (7%) that were conducted in urban fragments within the Atlantic Forest domain in the city of Rio de Janeiro, obtained a total superior to 1000 captures (Esbérard 2003; Esbérard et al. 2014). Besides the low sampling effort employed in urban environments, few studies were conducted for more than one year (e.g. Esbérard 2003; Perini et al. 2003; Costa et al. 2012; Esbérard et al. 2014) and none of them have analyzed aspects of biodiversity change and loss.

On the other hand, most of the bats listed here (70%) that are capable to use human constructions as roosts and consequently be ecologically more flexible, are aerial insectivores, especially molossids (40%). The ecological plasticity of aerial insectivores is discussed in many studies, which demonstrated a species-specific response mainly driven by the presence (Araújo and Bernard 2016) and distance to green areas (Jung and Kalko 2011), the bat flight characteristics (Jung and Kalko 2011), the type, setting and intensity of street lighting (Jung and Kalko 2010) and insect productivity (Avila-Flores and Fenton 2005). Araújo and Bernard (2016) using acoustic monitoring in the city of Recife, a large urban area of Brazil, found that the higher activity of Emballonuridae, Phyllostomidae and Vespertiolionidae was inside or near forest fragments, while molossid bats preferred non-green areas. In this sense, the fast-flying open space foragers of the family Molossidae are expected to be the most common bats associated with man-made constructions accordingly to our results (Esbérard et al. 1999; Reis et al. 2006; Bernardi et al. 2009; Pacheco et al. 2010; Albuquerque et al. 2012).

All families and guilds were found to be taking advantage of artificial and natural resources as a roost. However, the majority of studied roosts are artificial and highlights the efficiency of some bats to explore harsh environments particularly close to humans, such as garages, ceilings, and in some cases even lying in curtains inside houses (Perini et al. 2003). This roost list has a major relevance to the health surveillance and the urban species management and control by predicting encounters and avoidance of accidents with humans and domestic animals. Although bat proximity, as highlighted in the previous section, might provide insect control, the close proximity of bat roosts to humans and domestic animals may represents a direct risk of spillover events (Leroy et al. 2009; Wood et al. 2012), which is detrimental in terms of parasite transmission and disease epidemics. 041b061a72


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