International Journal of Molecular Zoology 2024, Vol.14, No.4, 233-243 http://animalscipublisher.com/index.php/ijmz 238 5.2 Impact of co-infections on health Co-infections can significantly impact the health of wildlife by altering the microbiome and influencing disease outcomes. The presence of multiple pathogens can lead to complex interactions within the host's microbiome, which can either exacerbate or mitigate disease severity. For example, the study on amphibian skin microbiomes revealed that the severity of Bd infection influenced the composition of the microbiome, with certain bacterial phylotypes changing in abundance as the infection progressed (Jani and Briggs, 2018). This dynamic interaction suggests that co-infections can disrupt the stability of the microbiome, potentially leading to increased susceptibility to additional pathogens. Moreover, the gut microbiome of American white ibises (Eudocimus albus) showed that urbanization and diet changes, which can be considered as environmental co-factors, were associated with shifts in microbiome composition and increased prevalence of Salmonella enterica, highlighting the role of environmental factors in co-infection dynamics (Murray et al., 2019). 5.3 Symbiotic relationships and disease resistance Symbiotic relationships between hosts and their microbiomes are fundamental to disease resistance. Symbiotic bacteria can provide colonization resistance against pathogens through various mechanisms, including competitive exclusion, production of antimicrobial compounds, and modulation of the host immune response (Tan et al., 2012; Libertucci and Young, 2018). For instance, the skin microbiome of amphibians has been shown to play a protective role against Bd infection, with certain bacterial communities being linked to host-pathogen coexistence rather than population extirpation. Additionally, the gut microbiome of cheetahs (Acinonyx jubatus) demonstrated that genetic relatedness and environmental factors shape the microbial community, which in turn influences the occurrence of potential pathogens and overall health (Wasimuddin et al., 2017). These symbiotic relationships underscore the importance of maintaining a healthy and diverse microbiome for effective disease resistance in wildlife. In summary, the microbiome's influence on disease susceptibility in wildlife is multifaceted, involving the diversity and composition of microbial communities, the impact of co-infections, and the symbiotic relationships that enhance host defense mechanisms. Understanding these interactions is crucial for developing strategies to mitigate the effects of infectious diseases in wildlife populations. 6 Case Study: Differential Infection in Andean Condors 6.1 Detailed analysis of the case study The Andean Condor (Vultur gryphus) serves as a critical case study for understanding differential infection in wildlife. These birds, essential for ecosystem health, are near threatened and face declining populations due to anthropogenic activities. Recent studies have identified pandemic lineages of multidrug-resistant extended-spectrum β-lactamase (ESBL)-producing Escherichia coli in Andean Condors. These pathogens, typically associated with hospital and healthcare environments, were found in condors admitted to wildlife rehabilitation centers in South America. The genomic analysis revealed resistance genes to clinically important cephalosporins and other substances, indicating a significant link to environmental pollution caused by human activities (Fuentes-Castillo et al., 2020). 6.2 Genetic, environmental, and behavioral factors The susceptibility and resistance to infections in Andean Condors are influenced by a combination of genetic, environmental, and behavioral factors. Genetically, the presence of specific resistance genes such as CTX-M-14, CTX-M-55, and CTX-M-65 in E. coli strains indicates a genetic predisposition to harboring these pathogens. Environmentally, the contamination of habitats with pollutants from human activities, including heavy metals, pesticides, and disinfectants, plays a crucial role in the spread of these resistant bacteria. Behaviorally, the scavenging nature of condors exposes them to a variety of pathogens present in carcasses and waste, increasing their risk of infection (Duxbury et al., 2018). 6.3 Lessons and broader implications The case of Andean Condors highlights the broader implications of differential infection in wildlife. Firstly, it underscores the significant impact of anthropogenic activities on wildlife health, particularly through
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