Senegal’s Ministry of Interior has ordered all movements of people through the southern boundary to Guinea suspended indefinitely to prevent the spread of the disease. Most of the cases detected in Guinea since January have been in the towns of Guekedou, Macenta, Kissidougou and Dabola, the country’s Health Ministry said Friday. There has been one death among eight cases in the capital, Conakry, it said. The transmission to Conakry, a city of 1.6 million people, represents a “new dynamic” in the outbreak, though the situation remains “extremely fluid,” Gregory Hartl, a WHO spokesman, said on Friday. Health authorities in bordering Sierra Leone and Liberia are investigating the deaths of people who had symptoms typical of Ebola. The outbreak involves the Zaire strain of Ebola, the most common and deadly of the five known varieties, with a mortality rate of as much as 90 percent.