Biology subjects

Hite, J.

Publications and source records attributed to Hite, J..

3 recordsLinked to original sources

bioRxiv2023

Global trends in antimicrobial resistance on organic and conventional farms

Various stewardship policies, regulations, and voluntary bans have focused on protecting antimicrobials by limiting their use in livestock. These efforts ignited management shifts ranging from largely nominal (e.g., drugs banned for use as growth promoters were reclassified as prophylactic drugs) to organic farming, which drastically reduces or eliminates use of antimicrobials. Understanding how these farming practices influence the prevalence of antimicrobial resistance in livestock carries important implications for policy makers, public health officials, and farm managers. Here, we reviewed studies spanning the last 20 years to ask if the most stringent effort to reduce antimicrobial use in livestock -- organic farming -- results in notable reductions in the prevalence of antimicrobial resistance across broad scale geographic ranges, pathogens, and livestock hosts. Our results validate organic farming in reducing the prevalence of antimicrobial resistance (AMR) by [~]31.2%,[~]26.9%, [~]28.2%,[~]42.9 and [~]36.2% in cattle, chicken, environment, pigs and turkey respectively while also revealing significant variation in the strength of this reduction across contexts. Given that our results join others indicating that AMR is increasing across all types of farms, our results highlight areas where organic farming has been most effective and may provide economical and scalable solutions for farmers.

microbiology↗

bioRxiv2022

Coinfection with chytrid genotypes drives divergent infection dynamics reflecting broad epidemiological patterns

By altering the abundance, diversity, and distribution of species -- and their pathogens -- globalization may inadvertently select for more virulent pathogens. In Brazils Atlantic Forest, a hotspot of amphibian biodiversity, the pet trade has facilitated the co-occurrence of previously isolated enzootic and panzootic lineages of the pathogenic amphibian-chytrid ( Bd) and generated new virulent recombinant genotypes ( hybrid). Epidemiological data indicate that amphibian declines are most severe in hybrid zones, suggesting that coinfections are causing more severe infections or selecting for higher virulence. We investigated how coinfections involving these genotypes shaped virulence and transmission. Overall, coinfection favored the more virulent and competitively superior panzootic genotype, despite dampening its virulence and transmission. However, for the least virulent and least competitive genotype, coinfection increased both pathogen virulence and transmission. Thus, by integrating experimental and epidemiological data, our results provide mechanistic insight into how globalization can select for, and propel, the emergence of introduced hypervirulent lineages, such as the globally distributed panzootic lineage of Bd.

ecology↗

bioRxiv2021

A paradox of parasite resistance: Disease-driven trophic cascades increase the cost of resistance, selecting for lower resistance with parasites than without them

Most evolutionary theory predicts that, during epidemics, hosts will evolve higher resistance to parasites that kill them. Here, we provide an alternative to that typical expectation, with an explanation centered on resource feedbacks. When resistance is costly, hosts evolve decreasing resistance without parasites, as expected. But with parasites, hosts can evolve lower resistance than they would in the absence of parasites. This outcome arises in an eco-evolutionary model when four conditions are met: first, resistance has a fecundity cost (here, via decreased foraging/exposure rate); second, resources increase during epidemics via trophic cascades; third, increased resources magnify the benefit of maintaining a fast foraging rate, thereby magnifying the cost of evolving a slower foraging/exposure rate (i.e., resistance); fourth, that amplification of the cost outweighs the benefit of resistance. When these conditions are met, hosts evolve lower resistance than without parasites. This phenomenon was previously observed in a mesocosm experiment with fungal parasites, zooplankton hosts, and algal resources. Re-analyzing this experiment produced evidence for our models mechanism. Thus, both model and experiment indicate that, via resource feedbacks, parasites can counterintuitively select against resistance.

ecology↗