Spillover of ebolaviruses into people in eastern Democratic Republic of Congo prior to the 2018 Ebola virus disease outbreak

Abstract

Background The second largest Ebola virus disease (EVD) outbreak began in the Democratic Republic of Congo in July 2018 in North Kivu Province. Data suggest the outbreak is not epidemiologically linked to the 2018 outbreak in Equateur Province, and that independent introduction of Ebola virus (EBOV) into humans occurred. We tested for antibodies to ebolaviruses in febrile patients seeking care in North Kivu Province prior to the EVD outbreak. Methods Patients were enrolled between May 2017 and April 2018, before the declared start of the outbreak in eastern DRC. Questionnaires were administered to collect demographic and behavioural information to identify risk factors for exposure. Biological samples were evaluated for ebolavirus nucleic acid, and for antibodies to ebolaviruses. Prevalence of exposure was calculated, and demographic factors evaluated for associations with ebolavirus serostatus. Results Samples were collected and tested from 272 people seeking care in the Rutshuru Health Zone in North Kivu Province. All patients were negative for filoviruses by PCR. Intial screening by indirect ELISA found that 30 people were reactive to EBOV-rGP. Results were supported by detection of ebolavirus reactive linear peptides using the Serochip platform. Differential screening of all reactive serum samples against the rGP of all six ebolaviruses and Marburg virus (MARV) showed that 29 people exhibited the strongest reactivity to EBOV and one to Bombali virus (BOMV), and western blotting confirmed results. Titers ranged from 1:100 to 1:12,800. Although both sexes and all ages tested positive for antibodies, women were significantly more likely to be positive and the majority of positives were in February 2018. Conclusions We provide the first documented evidence of exposure to Ebola virus in people in eastern DRC. We detected antibodies to EBOV in 10% of febrile patients seeking healthcare prior to the declaration of the 2018–2020 outbreak, suggesting early cases may have been missed or exposure ocurred without associated illness. We also report the first known detection of antibodies to BOMV, previously detected in bats in West and East Africa, and show that human exposure to BOMV has occurred. Our data suggest human exposure to ebolaviruses may be more frequent and geographically widespread.

Serological evidence of zoonotic filovirus exposure among bushmeat hunters in Guinea

“…Others have suggested that over a ve-year period, persistence of GP-speci c antibody responses is over 75% and 67% for at least two antigens 19 . Regarding the possibility of exposure to non-EBOV loviruses, the GP of Ebolaviruses is highly cross-reactive between species although the magnitude of GP antibody binding varies between Ebolavirus species 17,31 . EBOV convalescent sera exhibits pan-species neutralisation though the proportion of individuals exhibiting cross-species neutralisation also varies dependent on infecting strain 32,33 .…”

International law reform for One Health notifications

“…For example, before the Kivu Ebola virus disease outbreak in the Democratic Republic of the Congo (July, 2018, to June, 2020), a team of researchers found 10% Ebola virus seroprevalence in samples collected from the region from May, 2017, to April, 2018, indicating a risk of outbreaks in the area; the results were published in November, 2020. 23 Animal surveillance can also indicate that particular populations or areas face spillover risk, especially if viruses of concern are being detected in animals (and serological evidence indicates human exposure) at high-risk interfaces such as wildlife markets and supply chains, [24][25][26] or in domesticated animals. 13,[27][28][29] Thanks to methodological advances in experimental virology 30,31 and computational biology, 12,32,33 some wildlife viruses can even be identified as potential threats before the first known case of human infection, and gaps in countermeasures can also be assessed.…”

Ebola: uma ameaça à Saúde Pública e à fauna silvestre

“…Todos, exceto o REBOV, foram detectados apenas na África. O REBOV foi isolado, em 1990, em Reston (EUA), de macacos importados das Filipinas (GOLDSTEIN et al, 2020;GUMUSOVA;SUNBUL;LEBLEBICIOGLU, 2015;SINGH et al, 2017).…”

“…Com diferenças na patogenicidade, todas as espécies de vírus ebola, exceto provavelmente a BOMV, são associados à febre hemorrágica em humanos e primatas não humanos humanos (GOLDSTEIN et al, 2020). A estirpe REBOV é fatal para macacos, mas não é patogênica ou tem baixa patogenicidade para humanos, enquanto as estirpes ZEBOV e SEBOV têm alta virulência e elevada taxa de letalidade em humanos (SINGH et al, 2017).…”