BAMAKO, Mali — Mali reported its first case of Ebola late Thursday, marking a major setback for West African efforts to contain the deadly virus that now has affected six countries in the region and left nearly 5,000 dead. Health Minister Ousmane Kone made the announcement on Malian television, saying that the patient was a 2-year-old girl who had come from neighboring Guinea, where the Ebola epidemic began last December. The child was tested for the virus Wednesday at a hospital in the Malian town of Kayes, about 375 miles from the capital of Bamako.