Sierra Leone's national Ebola response chief says complacent behavior has led to a worrying spike in confirmed Ebola cases over the past week in four districts.

Alfred Palo Conteh, CEO of the National Ebola Response Centre, said Thursday that new measures must now be put into place to contain the surges.

Sierra Leone's Ministry of Health and Sanitation reported 15 cases Wednesday, along with 16 on Monday and Tuesday respectively.

Palo Conteh said that new Ebola hotspots have emerged in recent days in Cabala Town and Magazine Cut in the east of the capital, Freetown, where a number of confirmed cases have been recorded. The other hotspot is in the west of Freetown.

More than 3,600 people have died in Sierra Leone from Ebola, according to the World Health Organization.