An inverse association between West Nile virus serostatus and avian malaria infection status.

Matthew Ci Medeiros,Bethany L Krebs,Robert E Ricklefs,Edward D Walker,Jenni M Higashiguchi,Jeffrey D Brawn,Tavis K Anderson,Tony L Goldberg,Marilyn O Ruiz,Gabriel L Hamer,Uriel D Kitron

doi:10.1186/1756-3305-7-415

Abstract

BackgroundVarious ecological and physiological mechanisms might influence the probability that two or more pathogens may simultaneously or sequentially infect a host individual. Concurrent infections can have important consequences for host condition and fitness, including elevated mortality risks. In addition, interactions between coinfecting pathogens may have important implications for transmission dynamics.MethodsHere, we explore patterns of association between two common avian pathogens (West Nile virus and avian malaria parasites) among a suburban bird community in Chicago, IL, USA that share mosquito vectors. We surveyed 1714 individual birds across 13 species for both pathogens through established molecular protocols.ResultsField investigations of haemosporidian and West Nile virus (WNV) infections among sampled birds yielded an inverse association between WNV serostatus and Plasmodium infection status. This relationship occurred in adult birds but not in juveniles. There was no evidence for a relationship between Haemoproteus infection and WNV serostatus. We detected similar prevalence of Plasmodium among birds captured with active WNV infections and spatiotemporally paired WNV-naïve individuals of the same species, demonstrating that the two pathogens can co-infect hosts.ConclusionsMechanisms explaining the negative association between WNV serostatus and Plasmodium infection status remain unclear and must be resolved through experimental infection procedures. However, our results highlight potential interactions between two common avian pathogens that may influence their transmission among hosts. This is especially relevant considering that West Nile virus is a common zoonotic pathogen with public health implications. Moreover, both pathogens are instructive models in infectious disease ecology, and infection with either has fitness consequences for their avian hosts.Electronic supplementary materialThe online version of this article (doi:10.1186/1756-3305-7-415) contains supplementary material, which is available to authorized users.

Highlights

Various ecological and physiological mechanisms might influence the probability that two or more pathogens may simultaneously or sequentially infect a host individual
We explore the potential interaction between West Nile virus (WNV) and Haemosporida near Chicago, IL, USA, and show that WNV seropositive birds have a lower probability of haemosporidian infection
WNV serostatus was an important predictor of Haemosporida infection (Table 2)

Summary

Introduction

Various ecological and physiological mechanisms might influence the probability that two or more pathogens may simultaneously or sequentially infect a host individual. Few studies have explored the interactions of avian Haemosporida with other pathogens (in contrast to mammalian malaria [7,12], see Atkinson et al [5], Barnett [13]). This absence of knowledge is concerning because birds are primary reservoirs for many zoonotic pathogens, including arthropod-borne encephalitis viruses whose course of infection may be influenced by concurrent protozoan infections [12]. Understanding interactions between Haemosporida and other pathogens could have important implications for disease surveillance and animal and human health

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Discussion

Conclusion