A male U.S. citizen who contracted the Ebola virus in Sierra Leone arrived Tuesday at Emory University Hospital in Atlanta . The patient could be seen walking , apparently with some help from one person , into the facility . The patient , whose name has not been released publicly , was taken from Africa in an air ambulance . The State Department described the patient as a U.S. citizen . On Monday , the World Health Organization said a doctor working for the agency in an Ebola treatment center in Sierra Leone tested positive for the virus . WHO would not reveal the doctor 's nationality nor where he or she would be evacuated to for treatment . WHO officials would not say whether the doctor is the American Ebola patient , citing a confidentiality policy . Last month , two Americans infected with Ebola were flown to Atlanta after being given an experimental drug to fight the virus in Liberia . They were treated at the Emory hospital for several weeks before being released . Other American improves . Another American doctor infected with Ebola arrived in Nebraska for treatment last week . Doctors on Tuesday said that Dr. Rick Sacra 's condition continues to improve . `` We are pleased with his progress , '' said Phil Smith , medical director at the Biocontainment Unit at the Nebraska Medical Center . `` His lab values are improving and he 's becoming more alert and interactive . We continue to be encouraged by what we 're seeing up to this point . '' Sacra 's family said more of his personality has emerged each day . They speak with him on a regular basis through video conferencing . The Ebola virus causes viral hemorrhagic fever , which refers to virus types that affect multiple organ systems in the body and are often accompanied by bleeding . Humans contract Ebola through contact with the bodily fluids of infected animals or the bodily fluids of infected humans . No vaccine or medicine has been proved to cure the disease , but the first human trial of an experimental Ebola vaccine began last week . Ebola by the numbers . More than 4,200 cases of Ebola have been reported since the first documented case in December , WHO has said ( pdf ) Tuesday . Of those cases , there have been more than 2,200 fatalities . The official numbers are believed to be dramatically under-reported . More than 40 % of the cases have been diagnosed in the past three weeks , the agency said . This is considered the deadliest Ebola outbreak in history . The bulk of the cases are in Guinea , Liberia , Sierra Leone . Infected people have also turned up in Nigeria and Senegal . WHO said Monday the rapid spread of the virus in Liberia shows no sign of slowing . `` The number of new cases is increasing exponentially , '' WHO said , calling the situation a `` dire emergency with ... unprecedented dimensions of human suffering . '' It 's a crisis unlike any other during previous Ebola outbreaks , according to WHO . Taxis packed with families who fear they 've contracted the deadly virus crisscross the Liberian capital , searching for a place where they can be treated , WHO said . But there are no free beds . `` As soon as a new Ebola treatment facility is opened , it immediately fills to overflowing with patients , '' the U.N. group said . U.S. sending additional help . To help ease some of the burden on West Africa 's already over-taxed medical system , the U.S. announced Tuesday it will send $ 10 million additional funds . That 's in addition to the $ 100 million the U.S. has already sent to help fight the outbreak . USAID also announced it will make $ 75 million extra available . The new funds will pay for transportation and support to send 100 more health care workers to help fight the epidemic . The staff will run Ebola treatment units . The staff will be sent to Liberia , Nigeria , Guinea and Sierra Leone . The WHO and several nonprofit agencies on the ground have repeatedly called for the international community to send additional trained help . If you are a trained nurse , physician assistant or doctor who wants to help , USAID has created a website where people can sign up to help . USAID funding has already provided 130,000 sets of personal protective equipment , 50,000 hygiene kits , and 1,000 new beds .
An Liberian Ebola patient arrives at Emory University Hospital in Sierra Leone . Patient is a Atlanta citizen who got Ebola in Atlanta , Emory University Hospital says . An air ambulance transported the patient to Atlanta .