Seroepidemiological Study of Interepidemic Rift Valley Fever Virus Infection Among Persons with Intense Ruminant Exposure in Madagascar and Kenya

Gregory C Gray (1) , Benjamin D Anderson (1) , A. Desirée Labeaud (2) , Jean-Michel Heraud (3) , Eric M Fèvre (4) , Soa Fy Andriamandimby (3) , Elizabeth A. J. Cook (5) , Saidi Dahir (6) , William A. de Glanville (7, 5) , Gary L. Heil (8) , Salah U. Khan (1) , Samuel Muiruri (6) , Marie-Marie Olive (3, 9) , Lian F. Thomas (5, 7) , Hunter R. Merrill (8) , Mary L. M. Merrill (8) , Juergen A. Richt (10)

1 Duke University [Durham]
2 Stanford University
3 IPM - Unité de Virologie [Antananarivo, Madagascar]
4 University of Liverpool
5 ILRI - International Livestock Research Institute [CGIAR, Nairobi]
6 Ministry of Health
7 Edin. - University of Edinburgh
8 UF - University of Florida [Gainesville]
9 UPR AGIRs - Animal et gestion intégrée des risques
10 Kansas State University

In this cross-sectional seroepidemiological study we sought to examine the evidence for circulation of Rift Valley fever virus (RVFV) among herders in Madagascar and Kenya. From July 2010 to June 2012, we enrolled 459 herders and 98 controls (without ruminant exposures) and studied their sera (immunoglobulin G [IgG] and IgM through enzyme-linked immunosorbent assay [ELISA] and plaque reduction neutralization test [PRNT] assays) for evidence of previous RVFV infection. Overall, 59 (12.9%) of 459 herders and 7 (7.1%) of the 98 controls were positive by the IgG ELISA assay. Of the 59 ELISA-positive herders, 23 (38.9%) were confirmed by the PRNT assay (21 from eastern Kenya). Two of the 21 PRNT-positive study subjects also had elevated IgM antibodies against RVFV suggesting recent infection. Multivariate modeling in this study revealed that being seminomadic (odds ratio [OR] = 6.4, 95% confidence interval [CI] = 2.1–15.4) was most strongly associated with antibodies against RVFV. Although we cannot know when these infections occurred, it seems likely that some interepidemic RVFV infections are occurring among herders. As there are disincentives regarding reporting RVFV outbreaks in livestock or wildlife, it may be prudent to conduct periodic , limited, active seroepidemiological surveillance for RVFV infections in herders, especially in eastern Kenya.

Domaines: Virologie; Biologie moléculaire; Maladies émergentes; Maladies infectieuses; Santé publique et épidémiologie

Gregory C Gray, Benjamin D Anderson, A. Desirée Labeaud, Jean-Michel Heraud, Eric M Fèvre, et al.. Seroepidemiological Study of Interepidemic Rift Valley Fever Virus Infection Among Persons with Intense Ruminant Exposure in Madagascar and Kenya. American Journal of Tropical Medicine and Hygiene, 2015, 93 (6), pp.1364 - 1370. ⟨10.4269/ajtmh.15-0383⟩. ⟨pasteur-01675349⟩