Trojan hosts: the menace of invasive vertebrates as vectors of pathogens in the Southern Cone of South America

Abstract

Invasive alien species (IAS) can act as vectors for the introduction of pathogens in ecosystems and their transmission to threatened native species (TNS), leading to biodiversity loss, population reductions and extinctions. We assessed pathogens potentially occurring in a set of IAS in the Southern Cone of South America and identified TNS potentially vulnerable to their effects. Also, we assessed how risk analysis systems proposed or adopted by national authorities in the study region value the importance of pathogens. We identified 324 pathogens in the selected IAS, which could potentially affect 202 TNS. Wild boar (Sus scrofa) was the IAS with the largest number of pathogens (91), followed by domestic dog (Canis familiaris) (62), red deer (Cervus elaphus) (58), rock dove (Columba livia) (37), American vison (Neovison vison) (18), European hare (Lepus europaeus) (17), common starling (Sturnus vulgaris) (12), common slider (Trachemys scripta) (6), and American bullfrog (Lithobates catesbeianus) (2). Most TNS were in the ''vulnerable'' IUCN category, followed by ''endangered'' and ''critically endangered'' species. Bacteria were the most frequently represented pathogens (112), followed by ectoparasites (78), viruses (69), protozoa and other (65). The direct effects of IAS on native wildlife are beginning to be addressed in South America, and their potential impact as pathogen spreaders to native wildlife has remained largely unexplored. Risk analysis systems associated with the introduction of IAS are scarce in this region. Although the existing systems contemplate hazard analyses for the co-introduction of pathogens, they underestimate the potential impact of diseases on TNS. Conservation efforts in the region would benefit from systems which give pathogen risk a relevant place, and from government agencies promoting targeted disease surveillance in IAS and wildlife.

Mismatch between media coverage and research on invasive species: The case of wild boar (Sus scrofa) in Argentina

“…Both ecological and economic impacts are generally the most reported impacts of wild boar, providing the basis for different management strategies around the world (e.g., [ 43 , 44 ]). It is somewhat surprising that health impacts were not prominent in either article type given the diseases and parasites that wild boar host and the potential impacts on both wildlife and human health [ 45 ], especially after several major outbreaks of the African Swine Fever worldwide (e.g., [ 46 ]). However, health impacts of wild boar will likely become a more conspicuous topic both in news and scientific articles after the covid-19 pandemic and consequently increased awareness of the importance of zoonotic diseases [ 47 ].…”

Epidemiology of Pig Tuberculosis in Argentina

“…Wild boar is widely distributed in Argentina, with large populations coexisting in vast areas with pigs and cattle ( 53 ). In Argentina, pigs are produced mainly under extensive farming conditions, where cattle presence is also prominent and interaction between wild boar, pigs and cattle can be intense ( 53 , 54 ). Therefore, wild boar may act as a reservoir in the bTB epidemiology in regions with similar conditions as those in Argentina.…”

“…Health research and policy addressing wild boar diseases have received increased attention in recent years ( 55 , 56 ); however, the role of this species as spreader of bTB and other pathogens is far from being fully acknowledged ( 54 ). The surveillance strategy currently in place for bTB in cattle creates a complex scenario where pigs and wild boar continue to play their role as bTB sources for cattle, thus limiting the success of control programs.…”

Serological survey suggests circulation of coronavirus on wild Suina from Argentina, 2014–2017

“…The interaction between invasive species, native wildlife and domestic animals implies an increased risk of pathogen transmission (Barrios-Garcia and Ballari 2012 ; La Sala et al 2021 ). Moreover, disease transmission is a concern when wildlife reintroductions involve captive-bred animals as source populations, which can increase the risk of decline or extinction of wild populations (Earnhardt 2010 ).…”