The death toll in the Ebola outbreak has risen to 4,546 out of 9,191 known cases in Guinea, Liberia and Sierra Leone, the World Health Organization (WHO) said on Friday.

A further 20 cases including eight deaths in Nigeria, and one non-fatal case in Senegal, have also been recorded, it said.

In addition, Spain has recorded one local Ebola infection and the United States has three confirmed cases including one death, the WHO said in its latest update.

The death toll for the three countries with intense transmission of the virus includes 62 more deaths than on Wednesday. There are 239 health workers among the fatalities.

Earlier on Friday, the WHO declared an outbreak in Senegal officially over, after twice the maximum incubation period of 21 days had passed. A similar WHO statement on Nigeria is expected on Monday after the requisite 42 days.

A separate Ebola outbreak in Democratic Republic of Congo, from a different strain of the virus, has claimed 49 lives out of 68 known cases, the agency said.