title: Enemies and turncoats: bovine tuberculosis exposes pathogenic potential of Rift Valley fever virus in a common host, African buffalo (Syncerus caffer).
abstract: The ubiquity and importance of parasite co-infections in populations of free-living animals is beginning to be recognized, but few studies have demonstrated differential fitness effects of single infection versus co-infection in free-living populations. We investigated interactions between the emerging bacterial disease bovine tuberculosis (BTB) and the previously existing viral disease Rift Valley fever (RVF) in a competent reservoir host, African buffalo, combining data from a natural outbreak of RVF in captive buffalo at a buffalo breeding facility in 2008 with data collected from a neighbouring free-living herd of African buffalo in Kruger National Park. RVF infection was twice as likely in individual BTB+ buffalo as in BTB- buffalo, which, according to a mathematical model, may increase RVF outbreak size at the population level. In addition, co-infection was associated with a far higher rate of fetal abortion than other infection states. Immune interactions between BTB and RVF may underlie both of these interactions, since animals with BTB had decreased innate immunity and increased pro-inflammatory immune responses. This study is one of the first to demonstrate how the consequences of emerging infections extend beyond direct effects on host health, potentially altering the dynamics and fitness effects of infectious diseases that had previously existed in the ecosystem on free-ranging wildlife populations.
authors: College of Veterinary Medicine, Oregon State University, Dryden Hall, Corvallis, OR, USA breebeechler@gmail.com.
authors: B R
authors: BR
authors: Beechler
authors: Center for Computational Science, Tulane University, Tulane, LA, USA.
authors: C A
authors: CA
authors: Manore
authors: Mpumalanga State Veterinary Services, Nelspruit, Mpumalanga, South Africa.
authors: B
authors: B
authors: Reininghaus
authors: Odum School of Ecology and Department of Infectious Disease, University of Georgia, Athens, GA, USA.
authors: D
authors: D
authors: O'Neal
authors: Environmental Sciences, Oregon State University, OR, USA.
authors: E E
authors: EE
authors: Gorsich
authors: Odum School of Ecology and Department of Infectious Disease, University of Georgia, Athens, GA, USA.
authors: V O
authors: VO
authors: Ezenwa
authors: College of Veterinary Medicine, Oregon State University, Dryden Hall, Corvallis, OR, USA.
authors: A E
authors: AE
authors: Jolles
mesh_terms: D000034:Abortion, Veterinary / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000821:virology; D000818:Animals; D002020:Buffaloes; D002417:Cattle; D060085:Coinfection / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D004198:Disease Susceptibility / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D005260:Female; D007113:Immunity, Innate; D008297:Male; D008962:Models, Theoretical; D009163:Mycobacterium bovis / Q000502:physiology; D012295:Rift Valley Fever / Q000453:epidemiology* / Q000276:immunology / Q000821:virology; D012296:Rift Valley fever virus / Q000502:physiology; D013019:South Africa / Q000453:epidemiology; D014380:Tuberculosis, Bovine / Q000453:epidemiology* / Q000276:immunology / Q000382:microbiology
keywords: co-infection; disease dynamics; disease ecology; emerging infectious disease; invasive species; parasite interactions