Filovirus Seroreactivity Beyond Virus-Specific Outbreak Regions in the Democratic Republic of the Congo, 2015-2023
- 1Jonathan and Karin Fielding School of Public Health, University of California, Los Angeles
Abstract
The ongoing Bundibugyo virus disease (BVD) outbreak in the Democratic Republic of the Congo (DRC) is the second-largest Ebola disease outbreak in recorded history, and only the second recorded BVD outbreak in the country. While the DRC has recorded 18 filovirus disease outbreaks, the historical frequency and geographic distribution of human filovirus exposures remain poorly understood. Using a multiplexed multi-filovirus immunoassay, we assessed antibody reactivity against antigens of filoviruses linked to human disease, Bundibugyo virus (BDBV), Ebola virus (EBOV), Marburg virus (MARV), and Sudan virus (SUDV), among eleven cohorts from seven provinces between 2015-2023 (n=5,852). Participants with median fluorescence intensity values exceeding established antigen-specific cutoffs were classified as seroreactive. Seroreactivity against glycoprotein (GP) targets of all four viruses were detected in every cohort, demonstrating evidence of filovirus or an antigenically related exposure well beyond known outbreak regions. Seroreactivity estimates varied by cohort site, with 60.8% of participants (n=175/288) in Mongala Province in April 2016 considered seroreactive against BDBV GP. In this cohort, 4.2%, 29.9%, and 34.7% of participants were seroreactive against EBOV, MARV and SUDV GP, respectively yet only 1.7% were seroreactive against all four GP antigens. In adjusted analyses, site was the primary predictor of seroreactivity, with odds for BDBV seroreactivity 9.1-fold (95%CI 7.0-11.9) and 9.5-fold (95%CI 6.9-13.2) higher in Mongala and Tshuapa provinces than in Kwilu. Similarly, the adjusted odds of MARV and SUDV GP seroreactivity were 4.5-fold and 7.1-fold higher in Mongala, and 3.7-fold and 6.1-fold higher in Tshuapa, than Kwilu. Among 280 individuals sampled longitudinally, BDBV GP detected seroconversion was comparable by site, with 12.8% in Kwilu and 10.4% in Mongala having detected seroreactivity three and five years after initial contact, respectively. Overall, these results indicate widespread, geographically heterogeneous filovirus seroreactivity across sampled cohorts. These findings may reflect zoonotic spillover events, leading to undetected human-to-human filovirus circulation, including paucisymptomatic or asymptomatic infections, or exposure to as-yet unidentified antigenically cross-reactive viruses. These data highlight gaps in understanding the historical and geographic distribution of filovirus exposure in the DRC and support further prospective serological, epidemiological, and molecular investigations, especially given the current outbreak.
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BibTeX
@misc{merritt2026filovirus,
title = {{Filovirus Seroreactivity Beyond Virus-Specific Outbreak Regions in the Democratic Republic of the Congo, 2015-2023}},
author = {S. Merritt and J. P. Kompany and P. Mukadi and M. Halbrook and K. Musene and M. Beya and H. Kalengi and M. Tambu and J. D. Kelly and A. H. Ball and A. To and D. Mukadi-Bamuleka and M. Mossoko and H. L. Wallace and T. A. Wong and R. H. Doshi and D. McIlwain and C. W. Woods and B. P. Nicholson and L. E. Hensley and J. Kindrachuk and A. T. Lehrer and P. Mbala-Kingebeni and N. A. Hoff and A. W. Rimoin},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.20.26366019},
url = {https://www.medrxiv.org/content/10.64898/2026.10.20.26366019v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Filovirus Seroreactivity Beyond Virus-Specific Outbreak Regions in the Democratic Republic of the Congo, 2015-2023
AU - S. Merritt
AU - J. P. Kompany
AU - P. Mukadi
AU - M. Halbrook
AU - K. Musene
AU - M. Beya
AU - H. Kalengi
AU - M. Tambu
AU - J. D. Kelly
AU - A. H. Ball
AU - A. To
AU - D. Mukadi-Bamuleka
AU - M. Mossoko
AU - H. L. Wallace
AU - T. A. Wong
AU - R. H. Doshi
AU - D. McIlwain
AU - C. W. Woods
AU - B. P. Nicholson
AU - L. E. Hensley
AU - J. Kindrachuk
AU - A. T. Lehrer
AU - P. Mbala-Kingebeni
AU - N. A. Hoff
AU - A. W. Rimoin
PY - 2026
DA - 2026/10/20
PB - medRxiv
DO - 10.64898/2026.10.20.26366019
UR - https://www.medrxiv.org/content/10.64898/2026.10.20.26366019v1
AB - The ongoing Bundibugyo virus disease (BVD) outbreak in the Democratic Republic of the Congo (DRC) is the second-largest Ebola disease outbreak in recorded history, and only the second recorded BVD outbreak in the country. While the DRC has recorded 18 filovirus disease outbreaks, the historical frequency and geographic distribution of human filovirus exposures remain poorly understood. Using a multiplexed multi-filovirus immunoassay, we assessed antibody reactivity against antigens of filoviruses linked to human disease, Bundibugyo virus (BDBV), Ebola virus (EBOV), Marburg virus (MARV), and Sudan virus (SUDV), among eleven cohorts from seven provinces between 2015-2023 (n=5,852). Participants with median fluorescence intensity values exceeding established antigen-specific cutoffs were classified as seroreactive. Seroreactivity against glycoprotein (GP) targets of all four viruses were detected in every cohort, demonstrating evidence of filovirus or an antigenically related exposure well beyond known outbreak regions. Seroreactivity estimates varied by cohort site, with 60.8% of participants (n=175/288) in Mongala Province in April 2016 considered seroreactive against BDBV GP. In this cohort, 4.2%, 29.9%, and 34.7% of participants were seroreactive against EBOV, MARV and SUDV GP, respectively yet only 1.7% were seroreactive against all four GP antigens. In adjusted analyses, site was the primary predictor of seroreactivity, with odds for BDBV seroreactivity 9.1-fold (95%CI 7.0-11.9) and 9.5-fold (95%CI 6.9-13.2) higher in Mongala and Tshuapa provinces than in Kwilu. Similarly, the adjusted odds of MARV and SUDV GP seroreactivity were 4.5-fold and 7.1-fold higher in Mongala, and 3.7-fold and 6.1-fold higher in Tshuapa, than Kwilu. Among 280 individuals sampled longitudinally, BDBV GP detected seroconversion was comparable by site, with 12.8% in Kwilu and 10.4% in Mongala having detected seroreactivity three and five years after initial contact, respectively. Overall, these results indicate widespread, geographically heterogeneous filovirus seroreactivity across sampled cohorts. These findings may reflect zoonotic spillover events, leading to undetected human-to-human filovirus circulation, including paucisymptomatic or asymptomatic infections, or exposure to as-yet unidentified antigenically cross-reactive viruses. These data highlight gaps in understanding the historical and geographic distribution of filovirus exposure in the DRC and support further prospective serological, epidemiological, and molecular investigations, especially given the current outbreak.
ER -