The World Health Organization (WHO) is reporting 50 new cases of Ebola and 25 deaths in Sierra Leone, Liberia and Guinea since July 3. The virus continues to spread and grow in families, the WHO said.

The three countries have experienced the outbreak since February. A statement released by the United Nations agency shows the latest figures from health ministries reporting a total of 844 cases of Ebola and 518 deaths.

Guinea's health ministry reported two deaths since July 3, but no new cases of the virus in the past week, the WHO said. 

Sierra Leone has been the hardest hit by Ebola, with 34 of the new cases and 14 deaths. In Liberia, 16 new cases were reported as well as nine deaths. The WHO added that these new cases indicate the transmission of the virus in the community is continuing.

The WHO reports that the two main causes for transmission are those who stay at home to care for their relatives and transmissions at funerals.

"If we don't stop the transmission in the several hotspots in the three countries we will not be able to say that we control the outbreak," WHO spokeswoman Fadela Chaib said in a news briefing in Geneva.

One unnamed U.S. citizen, who was suspected of having Ebola because he fell ill after traveling to Sierra Leone and Guinea, has died. He was quarantined in a clinic in Ghana before passing away.

"We are aware that the deceased was tested for Ebola but the official cause of death has not yet been confirmed. Test results thus far have been inconclusive," a U.S. State Department official said in an email.

West African countries are trying to cooperate better with surrounding countries to try and fight the outbreak of Ebola. They're also developing better surveillance to detect the virus.

Doctors say if something isn't done, the Ebola virus could spread to more countries and even Europe.