Con­firmed cas­es in the Ebo­la out­break in east­ern Con­go have reached 1,003, in­clud­ing 254 deaths, of­fi­cials said, as trac­ing those who had been in con­tact with pa­tients re­mains a ma­jor chal­lenge.

A to­tal of 100 peo­ple have re­cov­ered in the out­break con­cen­trat­ed in the Ituri province since it was de­clared on May 15, Con­go’s Min­istry of Health said Sun­day. At least 365 pa­tients are in hos­pi­tals or in iso­la­tion, it said.

The Ebo­la out­break caused by the rare Bundibu­gyo virus, which has no vac­cines or treat­ment, was the worst ever in its first month. Of­fi­cials ad­mit there could be far more cas­es they still don’t know about and that the peak of the out­break is still ahead.