( CNN ) -- West African nations are turning to drastic measures in a desperate effort to stem the spread of the deadly Ebola virus . Guinea has closed its border with Sierra Leone , a border police official told CNN . Meanwhile , the Zambian government banned arrivals of people from countries where there has been an Ebola outbreak , as a preventive measure to stop the virus from entering the country . `` All delegates from any of the countries affected by Ebola Virus disease are restricted from entering Zambia until further notice , '' Dr. Joseph Kasonde , Zambia 's minister of health , said in a statement Saturday . The virulent virus continues to advance from its epicenter in Sierra Leone to nearby Guinea , Liberia and Nigeria . Other West African governments are attempting to contain the outbreak , which has been declared a `` public health emergency of international concern '' by the World Health Organization . Nearly 1,800 cases , including 961 deaths , are attributed to the virus , the World Health Organization says . Nigeria and Liberia have declared states of national emergency , in an effort to control the unprecedented epidemic . The United States and the United Kingdom vowed Saturday to increase assistance to help combat the disease in West Africa . Two missionaries who had traveled to Africa are being treated at Emory University Hospital in Atlanta . Canada , meanwhile , announced Sunday that a patient who recently traveled to Nigeria has tested negative for Ebola . The patient was treated in isolation after complaining of fever , headache and malaise . He is now doing well , said Eric Hoskins , minister of health and long-term care . `` Ontarians should know that we are fully prepared should any cases appear in the province , '' Hoskins said in a statement . `` This situation was the result of all our protocols working effectively . '' Treating Ebola in Sierra Leone : 'We are two steps behind ' Ebola virus : 9 things to know about the killer disease . WHO : Ebola outbreak in West Africa an international health emergency . Initial Ebola response called a 'failure ' Opinion : Make more Ebola drug and give it to Africans . CNN 's Nana Karikari-apau contributed to this report .
Nigeria says patient who traveled to Guinea tested negative for the virus . Zambia bans travelers from Ebola countries . Zambia , Guinea and Joseph Kasonde and Nigeria are battling Ebola .