Serologic Evidence of Hemorrhagic Fever Virus Spillover in Rural Liberia

Background Outbreaks of zoonotic emerging infectious diseases, including viral hemorrhagic fevers, are increasing in frequency. Clinical detection remains challenging due to the lack of pathognomonic signs or symptoms and limited access to diagnostics. To better understand the prevalence of prior exposure to viral hemorrhagic fever viruses, serum from community participants in rural Liberia was tested for IgG antibodies. Methods Serum collected from individuals enrolled in the ENABLE study, an observational study of Lassa fever virus incidence and seroprevalence, were analyzed for IgG against Ebola virus, Marburg virus, Lassa virus, Rift Valley Fever virus, Crimean-Congo hemorrhagic fever virus, pan-alphavirus, and pan-flavivirus by MAGPIX, a multiplex immune assay. Associations with seropositivity were evaluated using questionnaires that included demographic, animal, and environmental exposure information. Results Eighty-eight percent of samples from 456 participants tested positive for ≥1 of the viral antibodies with a majority (63%) having antibodies to ≥2 viruses. Seropositivity was highest for Lassa virus (67%) followed by pan-flavivirus (51%), pan-alphavirus (35%), Crimean-Congo hemorrhagic fever virus (24%), Ebolavirus (13%), Rift Valley Fever virus (9%) and Marburgvirus (8%). Older age, sex (variable by pathogen), exposure to cats and rats were associated with seropositivity. Conclusions These findings demonstrate a significant spillover of filoviruses, bunyaviruses, flaviviruses and alphaviruses in rural Liberia in contrast with an absence of detected outbreaks. These data support the need for enhanced surveillance and understanding of the ecological and behavioral risk factors for zoonotic spillover events, across a spectrum of disease presentation, given their potential and ongoing threat to global public health.