Unprotected and unadvised sexual activity is suspected in the latest case of Ebola in Liberia, just as the country approached 42 days without a new infection. 

Had Liberia surpassed the 42-day mark, it would have been declared Ebola-free. 

A 44-year-old woman died from the disease on Friday, and Deputy Health Minister Tolbert Nyenswah said there is evidence that she may have become infected through sexual contact. 

The Ebola virus appears in the semen of previously infected men for at least 82 days after they first exhibit symptoms, although there is no evidence that traces of the virus are still infectious in later stages.

Nevertheless, the World Health Organisation recommends that Ebola-infected individuals abstain from sex or practise safe sex for at least 90 days after their recovery. 

"Ebola survivors should consider correct and consistent use of condoms for all sexual acts beyond three months until more information is available," Nyenswah said. 

Authorities are monitoring over 200 people who came in contact with the deceased, although they have not shown symptoms of infection. 

The Ebola outbreak began in Guinea last year, and quickly spread to neighbouring countries. Over 10,000 people have died, and over 25,000 have been infected over the past 12 months. Cases in Liberia have generally decreased, while transmissions in Guinea and Sierra Leone continue to trouble health officials

"The emergency has continued longer than we had ever imagined," Christian Aid's Sierra Leone country manager, Jeanne Kamara, said in a statement last week. "It's not over yet, so complacency must not set in."

Sierra Leone lifted its nationwide lockdown on Sunday, although the country remains in a state of emergency. New emergency measures were also announced in Guinea on Saturday.