TY - JOUR T1 - Can Ebola Virus evolve to be less virulent in humans? JF - bioRxiv DO - 10.1101/108589 SP - 108589 AU - Mircea T. Sofonea AU - Lafi Aldakak AU - Luis Fernando Boullosa AU - Samuel Alizon Y1 - 2017/01/01 UR - http://biorxiv.org/content/early/2017/02/14/108589.abstract N2 - Understanding Ebola Virus (EBOV) virulence evolution is not only timely but also raises specific questions because it causes on the most virulent human infections and it is capable of transmission after the death of its host. Using a compartmental epidemiological model that captures all of the virus’ transmission routes, we infer the evolutionary dynamics of case fatality ratio (CFR) on the scale of an outbreak and on the long term. Our major finding is that the virus’s specific life cycle imposes selection for high levels of virulence and that this pattern is robust to parameter variations in biological ranges. In addition to shedding a new light on the adaptive reasons of EBOV’s high virulence, these results generate testable predictions and contribute to informing public health policies. In particular, burial management stands out as the most appropriate intervention since it decreases the R0 of the epidemics, while imposing selection for less virulent strains.Impact Summary The severe haemorrhagic fever caused by Ebola Virus (EBOV) usually kills more than one infected individual out of two in the absence of treatment, which makes this pathogen one of the most virulent known to humans. The recent outbreak in West Africa (2014-2016) revealed that the virus is able to spread and persist for months across countries. Given that microbes evolve rapidly, it is important to determine whether EBOV virulence is likely to decrease as the virus adapts to its human host. Indeed, some expect that virulence could be due to the fact that the virus is adapted to its reservoir host. To answer this question, we developed a novel mathematical model tailored to EBOV’s life cycle, notably by capturing its three main transmission route (by regular contact, sexual contact and via corpses). We investigated the evolutionary trends of EBOV’s virulence on different time scales (outbreak initiation, short term and long term). Our results reveal that unfortunately the virulence of EBOV is not due to the maladaptation of the virus, but rather the result of its unique life cycle. These results are robust to the parameter values chosen. From a public health perspective, burial management stands out as the main leverage to fight the virulence of EBOV, both on the short and long terms. ER -