Ebola virus. CDC/Frederick Murphy

Officials have announced a 67-year-old woman in the Kambia district of Sierra Leone died of Ebola, less than a week after the last Ebola patient in the country was discharged from hospital. Chief medical officer Dr. Brima Kargbo confirmed Sunday the death was caused by Ebola.

The last patient had been discharged Monday, an event that began a 42-day countdown to determine whether the World Health Organization (WHO) could declare the country free of Ebola transmission. It is unclear at this stage whether the woman died before or after the countdown started.

"We should not despair as we have been expecting this," said OB Sisay, director of the National Ebola Response Center. "We need to stay focused and maintain our discipline." The center has sent out teams to find out who had been in contact with the woman.

The Ebola crisis is far from over. The most recent outbreak of the disease was first reported in December 2013, but WHO said in July the outbreak is ongoing. A report published by the Ebola Interim Assessment Panel sharply criticized WHO's role in managing the crisis, saying the issue exposed serious failings in the organization's operations. More than 11,300 people have died so far in the current Ebola outbreak.

Even if a patient survives, chronic health issues can kick in. A report from WHO earlier this month revealed survivors can suffer from conditions such as joint pain and eye problems. There are an estimated 13,000 survivors in Guinea, Liberia and Sierra Leone.