# Serologic Evidence of Hemorrhagic Fever Virus Spillover in Rural Liberia

## TL;DR

A study in rural Liberia found high rates of past exposure to several hemorrhagic fever viruses, despite no reported outbreaks, suggesting a hidden public health risk.

## Contribution

The study provides novel serologic evidence of widespread spillover of multiple hemorrhagic fever viruses in rural Liberia.

## Key findings

- 88% of participants had antibodies to at least one hemorrhagic fever virus.
- Lassa virus had the highest seroprevalence at 67%, followed by pan-flavivirus at 51%.
- Exposure to cats and rats, along with age and sex, were associated with seropositivity.

## Abstract

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 immunoglobulin G antibodies.

Serum collected from individuals enrolled in the ENABLE study, an observational study of Lassa fever virus incidence and seroprevalence, were analyzed for immunoglobulin G 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.

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 Marburg virus (8%). Older age, sex (variable by pathogen), and exposure to cats and rats were associated with seropositivity.

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.

Sero-surveillance of a rural Liberian population revealed higher than expected exposure to viral hemorrhagic fever viruses, with a lack of reported outbreaks, highlighting the need for improved surveillance and diagnostics.