title: Seroepidemiological Study of Interepidemic Rift Valley Fever Virus Infection Among Persons with Intense Ruminant Exposure in Madagascar and Kenya.
abstract: 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.
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Gray
authors.forename: Benjamin D
authors.initials: BD
authors.lastname: Anderson
authors.forename: A Desirée
authors.initials: AD
authors.lastname: LaBeaud
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Heraud
authors.forename: Eric M
authors.initials: EM
authors.lastname: Fèvre
authors.forename: Soa Fy
authors.initials: SF
authors.lastname: Andriamandimby
authors.forename: Elizabeth A J
authors.initials: EAJ
authors.lastname: Cook
authors.forename: Saidi
authors.initials: S
authors.lastname: Dahir
authors.forename: William A
authors.initials: WA
authors.lastname: de Glanville
authors.forename: Gary L
authors.initials: GL
authors.lastname: Heil
authors.forename: Salah U
authors.initials: SU
authors.lastname: Khan
authors.forename: Samuel
authors.initials: S
authors.lastname: Muiruri
authors.forename: Marie-Marie
authors.initials: MM
authors.lastname: Olive
authors.forename: Lian F
authors.initials: LF
authors.lastname: Thomas
authors.forename: Hunter R
authors.initials: HR
authors.lastname: Merrill
authors.forename: Mary L M
authors.initials: MLM
authors.lastname: Merrill
authors.forename: Juergen A
authors.initials: JA
authors.lastname: Richt
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D058872:Epidemics / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D007630:Kenya / Q000453:epidemiology; D008270:Madagascar / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests; D012295:Rift Valley Fever / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D012296:Rift Valley fever virus / Q000276:immunology / Q000502:physiology; D012307:Risk Factors; D012418:Ruminants / Q000821:virology*; D055815:Young Adult; D015047:Zoonoses / Q000453:epidemiology / Q000821:virology
chemical_list: D000914:Antibodies, Viral; D007075:Immunoglobulin M