Screen Shot 2014-04-17 At 7.45.12 AmA new study released this week from the New England Journal of Medicine (NEJM) demonstrates the emergence of a new Ebola (EBOV) strain in Guinea. Full-length genome sequencing and phylogenetic analysis showed that EBOV from Guinea forms a separate clade in relationship to the known EBOV strains from the Democratic Republic of Congo and Gabon. Epidemiologic investigation linked the laboratory-confirmed cases with the presumed first fatality of the outbreak in December 2013.

This is evidence that the disease did not spread there from outbreaks in some other African nations and the source of the virus remains unknown at this time.  Earlier, health officials had said the Guinea Ebola was a Zaire strain, different from the kind that has caused cases in other parts of Africa. The Democratic Republic of Congo used to be called Zaire.

Researchers think the Guinea and other strains evolved in parallel from a recent ancestor virus. The Guinea outbreak likely began last December or earlier and might have been smoldering for some time unrecognized. The investigation continues to try to identify “the presumed animal source,” they write.

The full report may be downloaded from NEJM: