Arenavirus infection correlates with lower survival of its natural rodent host in a long-term capture-mark-recapture study

Joachim Mariën,Bram Vanden Broecke,Loth S Mulungu,Herwig Leirs,Joëlle Goüy De Bellocq,Christopher A Sabuni,Abdul A S Katakweba,Vincent Sluydts,Apia W Massawe,Benny Borremans,Sophie Gryseels,Stephan Günther

doi:10.1186/s13071-018-2674-2

Abstract

BackgroundParasite evolution is hypothesized to select for levels of parasite virulence that maximise transmission success. When host population densities fluctuate, low levels of virulence with limited impact on the host are expected, as this should increase the likelihood of surviving periods of low host density. We examined the effects of Morogoro arenavirus on the survival and recapture probability of multimammate mice (Mastomys natalensis) using a seven-year capture-mark-recapture time series. Mastomys natalensis is the natural host of Morogoro virus and is known for its strong seasonal density fluctuations.ResultsAntibody presence was negatively correlated with survival probability (effect size: 5–8% per month depending on season) but positively with recapture probability (effect size: 8%).ConclusionsThe small negative correlation between host survival probability and antibody presence suggests that either the virus has a negative effect on host condition, or that hosts with lower survival probability are more likely to obtain Morogoro virus infection, for example due to particular behavioural or immunological traits. The latter hypothesis is supported by the positive correlation between antibody status and recapture probability which suggests that risky behaviour might increase the probability of becoming infected.

Highlights

Parasite evolution is hypothesized to select for levels of parasite virulence that maximise transmission success
We found no adverse relationship between Morogoro virus (MORV) infection and body condition, we were not able to exclude the possibility that animals become lethargic or die quicker due to infection and have a lower capture probability
For this reason we investigate whether MORV reduces the survival and recapture probability of M. natalensis using a seven-year capture-mark-recapture (CMR) dataset

Summary

Introduction

Parasite evolution is hypothesized to select for levels of parasite virulence that maximise transmission success. Host population density is a key factor in determining whether low or high virulence will be optimal [9–11] This mechanism can be understood in the framework of a trade-off between a microparasite’s competitive ability and its persistence. A strain with a short infectious period but high reproductive rate (high virulence) will have an advantage at high host density, as it will outcompete strains with lower reproductive rate. These host density effects could be especially important during virulence evolution of wildlife parasites, as their hosts are more likely to experience strong density fluctuations [12]

Methods

Results

Discussion

Conclusion