Sierra Leone placed hundreds of homes in the capital under Ebola quarantine on Friday, in a huge blow to its recovery less than a month after lifting travel restrictions.
"Some 700 homes have been quarantined for 21 days in the tourism and fishing community of Aberdeen in the west of the capital Freetown, after the death of a fisherman who was later diagnosed Ebola positive," said Obi Sesay of the government's National Ebola Response Centre.
The west African nation of six million had seen almost 11,000 cases and 3,363 deaths during the epidemic which has raged in west Africa for more than a year.
This new struggle with the disease comes less than a month after President Ernest Bai Koroma pointed to a "steady downward trend" in new cases and lifted country-wide quarantines and travel bans.
When ending the measures, which impacted half the population, on January 23 the president said "victory is in sight".
But optimism that the worst was over gave way to renewed concern on Wednesday as the World Health Organization (WHO) reported the number of new confirmed cases rising across Sierra Leone and Guinea for the second week running.
Transmission remains "widespread" in Sierra Leone, which reported 76 new confirmed cases in the week to February 8, according to the WHO.
"Twenty or more confirmed cases have been discovered in the last few days and we have opened a control centre to deal with the crisis," Sesay told reporters.
"We are on top of the situation and people should not panic."
Sesay said the Aberdeen area, which includes the popular Lumley Beach tourist resort, had been "flooded" with surveillance officers and contact tracers to ensure the death didn't turn into a serious outbreak.