A1 Journal article (refereed)
Sequential infection can decrease virulence in a fish‐bacterium‐fluke interaction : implications for aquaculture disease management (2019)

Karvonen, A., Fenton, A., & Sundberg, L.-R. (2019). Sequential infection can decrease virulence in a fish‐bacterium‐fluke interaction : implications for aquaculture disease management. Evolutionary Applications, 12(10), 1900-1911. https://doi.org/10.1111/eva.12850

JYU authors or editors

Karvonen, Anssi
Sundberg, Lotta-Riina

Publication details

All authors or editors: Karvonen, Anssi; Fenton, Andy; Sundberg, Lotta-Riina

Journal or series: Evolutionary Applications

eISSN: 1752-4571

Publication year: 2019

Volume: 12

Issue number: 10

Pages range: 1900-1911

Publisher: Wiley-Blackwell Publishing, Inc.

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1111/eva.12850

Research data link: 10.5061/dryad.8f57ck3

Publication open access: Openly available

Publication channel open access: Open Access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/66161

Abstract

Hosts are typically infected with multiple strains or genotypes of one or several parasite species. These infections can take place simultaneously, but also at different times, i.e. sequentially, when one of the parasites establishes first. Sequential parasite dynamics are common in nature, but also in intensive farming units such as aquaculture. However, knowledge of effects of previous exposures on virulence of current infections in intensive farming is very limited. This is critical as consecutive epidemics and infection history of a host could underlie failures in management practises and medical intervention of diseases. Here, we explored effects of timing of multiple infection on virulence in two common aquaculture parasites, the bacterium Flavobacterium columnare and the fluke Diplostomum pseudospathaceum. We exposed fish hosts first to flukes and then to bacteria in two separate experiments, altering timing between the infections from few hours to several weeks. We found that both short‐term and long‐term difference in timing of the two infections resulted in significant, genotype‐specific decrease in bacterial virulence. Second, we developed a mathematical model, parameterized from our experimental results, to predict the implications of sequential infections for epidemiological progression of the disease, and levels of fish population suppression, in an aquaculture setting. Predictions of the model showed that sequential exposure of hosts can decrease the population‐level impact of the bacterial epidemic, primarily through the increased recovery rate of sequentially infected hosts, thereby substantially protecting the population from the detrimental impact of infection. However, these effects depended on bacterial strain–fluke genotype combinations, suggesting the genetic composition of the parasite populations can greatly influence the degree of host suppression. Overall, these results suggest that host infection history can have significant consequences for the impact of infection at host population level, potentially shaping parasite epidemiology, disease dynamics and evolution of virulence in farming environments.

Keywords: epidemiology; infections; aquaculture

Free keywords: dynamic infection; epidemiology; multiple infection; sequential infection; spatiotemporal variation; aquaculture

Fields of science: