Genomics reveals zoonotic and sustained human Mpox spread in West Africa.
Parker E., Omah IF., Djuicy DD., Magee A., Tomkins-Tinch CH., Otieno JR., Varilly P., Ayinla AO., Sijuwola AE., Ahmed MI., Ope-Ewe OO., Ogunsanya OA., Olono A., Saibu FM., Eromon P., Moumbeket Yifomnjou MH., Messanga Essengue LL., Yonga MGW., Essima GD., Touoyem IP., Mounchili LJM., Eyangoh SI., Etoundi AGM., Esso L., Nguidjol IME., Metomb SF., Chebo C., Agwe SM., Mossi HM., Bilounga CN., Akanbi O., Egwuenu A., Ehiakhamen O., Chukwu C., Suleiman K., Akinpelu A., Ahmad A., Imam KI., Ojedele R., Oripenaye V., Ikeata K., Adelakun S., Olajumoke B., O'Toole Á., Zeller M., Gangavarapu K., Park DJ., Mboowa G., Tessema SK., Tebeje YK., Folarin O., Happi A., Lemey P., Suchard MA., Andersen KG., Sabeti P., Rambaut A., Ihekweazu C., Jide I., Adetifa I., Njouom R., Happi CT.
Five years before the 2022 multi-country mpox outbreak, Nigeria and Cameroon reported their first cases in over three decades.1,2 While Nigeria's outbreak is recognized as an ongoing human epidemic, the drivers of Cameroon's resurgence remain unclear.3,4 The rate of zoonoses remains uncertain in both countries, and gaps in genomic data obscure the timing, zoonotic and geographic origin of mpox virus (MPXV) emergence in humans. To address these uncertainties, we generated 118 MPXV genomes from Nigeria and Cameroon from 2018-2023. Our findings show that, in contrast to Nigeria, cases in Cameroon are the result of repeated zoonoses, with two distinct zoonotic lineages circulating across the Nigeria-Cameroon border. Our findings suggest that shared animal populations in the cross-border forest ecosystems drive virus emergence and spread. Accordingly, we identify the closest zoonotic outgroup to the Nigerian human epidemic lineage (hMPXV-1) in a southern Nigerian border state. We estimate that the shared ancestor of the zoonotic outgroup and hMPXV-1 circulated in animals in southern Nigeria in late 2013. We estimate that hMPXV-1 emerged in humans in August 2014 in the southern Rivers State and circulated undetected for three years. Rivers State acted as the main source of viral spread across the human epidemic. Our study sheds light on MPXV's recent establishment in the human population and highlights the risk of persistent zoonotic emergence of MPXV in the complex border regions of Cameroon and Nigeria.