Journal Article

Heterogeneity of Rift Valley fever virus transmission potential across livestock hosts, quantified through a model-based analysis of host viral load and vector infection

Ezanno, Pauline, Vriens, Roosmarie, Wichgers Schreur, Paul, This work was supported by INRAE metaprogram GISA (Integrated Management of Animal Health, project FORESEE), INRAE (HC), Conseil Régional des Pays de la Loire (HC), CIRAD (HC), and the Dutch research council (NWO, One Health PACT project 109986, MdW). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript, Wageningen BioVeterinary Research ; Wageningen University and Research [Wageningen] (WUR), de Wit, Mariken, ten Bosch, Quirine, Métras, Raphaëlle, Cecilia, Hélène, Biologie, Epidémiologie et analyse de risque en Santé Animale (BIOEPAR) ; École nationale vétérinaire, agroalimentaire et de l'alimentation Nantes-Atlantique (ONIRIS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Wageningen University and Research [Wageningen] (WUR), Institut Pierre Louis d'Epidémiologie et de Santé Publique (iPLESP) ; Institut National de la Santé et d

2022

Overview

Quantifying the variation of pathogens’ life history traits in multiple host systems is crucial to understand their transmission dynamics. It is particularly important for arthropod-borne viruses (arboviruses), which are prone to infecting several species of vertebrate hosts. Here, we focus on how host-pathogen interactions determine the ability of host species to transmit a virus to susceptible vectors upon a potentially infectious contact. Rift Valley fever (RVF) is a viral, vector-borne, zoonotic disease, chosen as a case study. The relative contributions of livestock species to RVFV transmission has not been previously quantified. To estimate their potential to transmit the virus over the course of their infection, we 1) fitted a within-host model to viral RNA and infectious virus measures, obtained daily from infected lambs, calves, and young goats, 2) estimated the relationship between vertebrate host infectious titers and probability to infect mosquitoes, and 3) estimated the net infectiousness of each host species over the duration of their infectious periods, taking into account different survival outcomes for lambs. Our results indicate that the efficiency of viral replication, along with the lifespan of infectious particles, could be sources of heterogeneity between hosts. Given available data on RVFV competent vectors, we found that, for similar infectious titers, infection rates in the Aedes genus were on average higher than in the Culex genus. Consequently, for Aedes -mediated infections, we estimated the net infectiousness of lambs to be 2.93 (median) and 3.65 times higher than that of calves and goats, respectively. In lambs, we estimated the overall infectiousness to be 1.93 times higher in individuals which eventually died from the infection than in those recovering. Beyond infectiousness, the relative contributions of host species to transmission depend on local ecological factors, including relative abundances and vector host-feeding preferences. Quantifying these contributions will ultimately help design efficient, targeted, surveillance and vaccination strategies.

• Publisher: PLOS,CCSD,Public Library of Science,Public Library of Science (PLoS)
• Subject: Aedes / Analysis / Animals / Aquatic insects / Biology and Life Sciences / Calves / Case studies / Coccidioidomycosis / Contact potentials / Disease transmission / Distribution / Genetic vectors / Goats / Hepatitis / Heterogeneity / Host systems / Host-parasite relationships / Host-pathogen interactions / Infections / Influenza / Lamb / Life history / Life Sciences / Life span / Livestock / Medicine and Health Sciences / Mosquitoes / Parameter estimation / Pathogens / Rift Valley fever / RNA viruses / Sheep / Species / Vaccination / Vector-borne diseases / Vectors / Vertebrates / Viral diseases / Viruses / Zoonoses