Another surprising conclusion: the tree branch leading to the 2021 viruses is much shorter than expected. By applying molecular clock models (whose ‘ticking’ represents the more or less regular accumulation of mutations over time), a slowing down of the rate of evolution by a factor of 6 can be detected. Truth be told, when these same models are asked to estimate the age of the 2021 sequences, they suggest the date of 2015, placing them at the heart of the previous epidemic.
These results clearly indicate that the 2021 epidemic does not follow a new zoonotic emergence but rather represents a resurgence of that of 2014-6. One of the possible mechanisms is a latency or dormancy of the virus in immunoprivileged anatomical sites; we know, for example, that the virus can persist for months in the semen of cured patients. We now also know that similar resurgences took place during other epidemics, for example during that of North Kivu in 2018-20. The 2021 epidemic in Guinea demonstrates, however, that such events can occur much longer after the end of a previous epidemic than we previously thought.
About 20,000 people have survived EVD outbreaks over the past 10 years. The discovery of EVD resurgences shows that monitoring these patients is absolutely crucial to prevent future outbreaks. This monitoring should include appropriate support measures, to prevent these already very vulnerable populations from being further stigmatized.
Sebastien Calvignac-Spencer, Ph.D.
Epidemiology of Highly Pathogenic Microorganisms Viral Evolution Robert Koch Institut
[email protected]
www.leendertz-lab.org www.pathogen-museomics.org
Read the source article:
Keita AK, Koundouno FR, Faye M, Düx A, Hinzmann J, Diallo H, Ayouba A, Le Marcis F, Soropogui B, Ifono K, Diagne MM, Sow MS, Bore JA, Calvignac-Spencer S, Vidal N, Camara J , Keita MB, Renevey A, Diallo A, Soumah AK, Millimono SL, Mari-Saez A, Diop M, Doré A, Soumah FY, Kourouma K, Vielle NJ, Loucoubar C, Camara I, Kourouma K, Annibaldis G, Bah A , Thielebein A, Pahlmann M, Pullan ST, Carroll MW, Quick J, Formenty P, Legand A, Pietro K, Wiley MR, Tordo N, Peyrefitte C, McCrone JT, Rambaut A, Sidibé Y, Barry MD, Kourouma M, Saouromou CD, Condé M, Baldé M, Povogui M, Keita S, Diakite M, Bah MS, Sidibe A, Diakite D, Sako FB, Traore FA, Ki-Zerbo GA, Lemey P, Günther S, Kafetzopoulou LE, Sall AA, Delaporte E, Duraffour S, Faye O, Leendertz FH, Peeters M, Toure A, Magassouba NF. Resurgence of Ebola virus in 2021 in Guinea suggests a new paradigm for outbreaks. Nature. 2021 Sep; 597 (7877): 539-543. doi: 10.1038 / s41586-021-03901-9. Epub 2021 Sep 15. PMID: 34526718.
https://pubmed.ncbi.nlm.nih.gov/34526718/
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