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Parasites and Conservation Biology
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
It is not uncommon for parasites to be introduced along with their hosts into new environments, which is an example of pathogen pollution. In their new habitat, the introduced parasites might simply die out for lack of appropriate intermediate hosts for example, or they might remain confined to their original introduced host species, or they may “spillover” into indigenous host species as well, potentially with adverse effects on their newly acquired hosts (Figures 8.15 and 8.16). Co-introductions leading to spillover of parasites is considered less likely if the parasite in question is rare in its host of origin or if the introduced host itself is rare, and more likely if it were a generalist parasite with a broad host range to start with. The term spillover is also used to refer to the transfer of a parasite from a domestic or commercial population of hosts into a wild host population, such as described above for the transfer of Nosema apis from commercial to wild bumble bee populations or for transfer of Lepeophtheirus salmonis from penned to wild salmonids.
Novel Scientific Approaches to Understanding Emerging Infectious Diseases
Published in Kezia Barker, Robert A. Francis, Routledge Handbook of Biosecurity and Invasive Species, 2021
Morens et al. (2004, 242) defined EIDs as ‘infections that have newly appeared in a population or have existed previously but are rapidly increasing in incidence or geographic range’. They further subdivide EIDs into those that are ‘newly emerging’ (i.e. not previously recognised) and those that are ‘re-emerging/resurging’ (i.e. diseases that were a problem before declining dramatically and then increasing again) (Morens et al., 2004). More than 60% of EIDs are zoonotic (i.e. they originated in animals), and over 70% of these originated in wild animals (Jones et al., 2008). While some of these transmit directly to humans, the transmission of emerging infections is often complex and can involve several host species (Wendelboe et al., 2010). In fact, emerging pathogens frequently exhibit a broad host range (Woolhouse and Gowtage-Sequeria, 2005), yet how animal-adapted pathogens make the jump and adapt to new species such as humans still remains largely unknown. With a view to improving surveillance and outbreak preparedness, various studies have developed geographical risk assessment frameworks in an attempt to identify areas of highest risk for spillover of key pathogens, such as avian and swine influenza, into the human population (Hill et al., 2015; Berger et al., 2018). However, others claim that it is impossible to predict where or when the next pandemic will occur, and teasing apart the details of such mechanisms remains an important challenge in understanding EIDs (Morens and Fauci, 2012).
Animal Tuberculosis
Published in Lloyd N. Friedman, Martin Dedicoat, Peter D. O. Davies, Clinical Tuberculosis, 2020
Cattle are the major maintenance host of M. bovis, and therefore are capable of maintaining the infection within their population. “Spillover” hosts can be defined as those in which the animal species may become infected, but are not particularly effective at transmitting the infection between other members of the same species. In the case of M. bovis, these spillover hosts include, among others, humans, cats, and dogs.
Modern vaccine strategies for emerging zoonotic viruses
Published in Expert Review of Vaccines, 2022
Atif Ahmed, Muhammad Safdar, Samran Sardar, Sahar Yousaf, Fiza Farooq, Ali Raza, Muhammad Shahid, Kausar Malik, Samia Afzal
The emergence of novel pathogens from the animal reservoir with enhanced capacity for dissemination is another potential threat to public health [1]. The occurrence of infectious diseases through zoonosis has significantly increased in number and severity over the last two decades [2]. Zoonotic pathogens are responsible for 65% of emerging infectious diseases in humans and are mostly related to viruses [3]. The cryptic transmission of zoonotic intracellular parasites is a unique property that promotes successful dissemination in the susceptible population until its proper diagnosis. These are mostly respiratory diseases and primarily spread in the human population through breathing; however, few viral particles follow alternate pathways of transmission, but their transmissibility is low. These infections originate from the spillover of pathogens from animal reservoirs that exhibit several new characteristics along with few previous features. Therefore, zoonotic viruses either reemerge in the same geographical regions with mutated genotypes or emerge in different geographical territories with similar gene sets. The emerging and reemerging viral diseases in different geographical locations through distinct animal reservoirs with unique transmission patterns are discussed in Table 1. However, the unpredictable nature, elevated case fatality rates, uncertainty in the determination of responsible animal reservoir, and unidentified modes of transmission are distinguished features of zoonotic organisms making it a global threat to human health [4].
Quantifying spillover benefits in value assessment: a case study of increased graft survival on the US kidney transplant waitlist
Published in Journal of Medical Economics, 2021
Syvart Dennen, Oliver Díaz Espinosa, Kelly Birch, Jennifer Cai, Jennifer C. Sung, Paula G. P. Machado, Jason Shafrin
Although the incidence of graft failure has declined in recent decades, it still imposes a substantial burden on patients in the long-term; the most recent OPTN data shows 5-year graft survival among deceased donor kidney transplants is 74%14. Graft failure can be caused by acute rejection, glomerular disease, fibrosis/atrophy, and as an event secondary to separate medical or surgical conditions56. Recent pharmaceutical innovation has increased graft survival43,57–60. While the current study is hypothetical in nature, the results of existing studies could be further translated into a broader range of real-world impacts by accounting for the spillover impact described in the present paper. Further areas for continued discussion include better characterization of donor-specific antibodies, increased attention to patient adherence to immunosuppressive drugs, and overall long-term investment in better patient access to health care resources and medications61. Further, advances in life expectancy have led to an increase in elderly people with ESRD who may be candidates for transplant; these patients are likely to have greater comorbidities and require more complex regimens post-transplant62. Increased emphasis on post-transplant care is especially necessary to ensure graft survival in these patients.
A review of mechanistic models of viral dynamics in bat reservoirs for zoonotic disease
Published in Pathogens and Global Health, 2020
Anecia D. Gentles, Sarah Guth, Carly Rozins, Cara E. Brook
Predicting and preventing zoonotic emergence – or the cross-species spillover of a pathogen from a wildlife reservoir to a human host – first requires understanding transmission and infection dynamics in the reservoir population. Despite the public health impact of bat-borne zoonoses, the mechanisms by which bats maintain pathogens at the population level, including the extent to which they experience within-host infection-induced morbidity or mortality, remain poorly characterized [10–12]. Understanding these mechanisms will be critical for predicting future cross-species spillover events, as well as informing strategies of possible public health intervention. Compartmental models offer an essential tool for elucidating the mechanisms underpinning reservoir bat transmission, as they can be applied to longitudinally collected field data from bat systems to test transmission hypotheses.