The journal Science publishes this week a study which shows that the Zaire strain of Ebola virus (ZEBOV) is the most common cause of death in populations of large apes, principally gorillas and chimpanzees, in the Lossi wildlife sanctuary, situated in the north-east of the Republic of the Congo ( Brazzaville ). From a nest census over an area of 5,000 km 2 it is estimated that ZEBOV has killed a total of 5,000 gorillas.

The study was written by José Domingo Rodríguez Teijeiro, Head of Animal Biology at the University of Barcelona, Magdalena Bermejo, associate researcher with the Department of Animal Biology, and a third contributor, Alex Barroso, with the participation of Germán Illera, an associate researcher from the European Union ECOFAC program, Carles Vilà, Associate Professor of the Department of Evolutionary Biology at the University of Uppsala (Sweden), and Peter Walsh, a researcher from the Max Planck Institute for Evolutionary Anthropology (Germany).

The authors of the study have confirmed that the delay in the onset of mortality between the neighbouring groups of gorillas studied is very similar to the length of the ZEBOV disease cycle (twelve days), which proves that mortality has been increased by the transmission between groups. The research concludes that the death of more than 5,000 gorillas in the studied area is a unique loss of numbers in an animal population in such a short space of time, and proves that transmission between families increases the number of deaths. Until now it had been thought that the virus was transmitted through various sources of infection between disease-carrying species ( Nature published an article at the beginning of this year in which it was suggested that these may be certain species of bats) and the gorillas.