Dallas County Health and Human Services spokeswoman Erikka Neroes said Thursday about 80 people are now part of the "contact investigation." Neroes said no one is showing symptoms.
She says the number includes 12 to 18 people who first came into contact with Thomas Eric Duncan, as well as others known to have secondhand contact.
Health officials have educated the people on the symptoms of Ebola and told them to notify health workers if they feel ill.
Health officials are focusing on containment to try to keep the virus from spreading. Duncan recently travelled from Liberia to Dallas.