Tedros Adhanom Ghebreyesus, director-general of the World Health Organisation, has commended the Nigerian government after 62 identified contacts traced to the index Ebola patient completed three weeks of monitoring without testing positive for the virus.

Mr Ghebreyesus hailed Nigeria’s preparedness and response system for containing the virus.

“A positive milestone in #Nigeria’s #Ebola response: all 62 identified contacts of the case reported on 20 October have completed 21 days of monitoring, with no secondary transmission detected,” the WHO chief wrote in a statement on Friday.

Mr Ghebreyesus said Nigeria had entered the second half of the mandatory 42-day countdown required to be declared Ebola-free.

“As the second half of the 42-day countdown begins, @WHO maintains its support and heightened vigilance,” Mr Ghebreyesus said.

“My congratulations to the government, health workers and responders for their success in preventing the spread of the Bundibugyo virus.”

For a country to be certified free of an infectious disease, it must complete the WHO’s required 42-day period without recording a new confirmed case.

Nigeria is on track to achieving Ebola-free status by December 7, provided no new case is recorded.

Nigeria recorded its first Ebola case on October 20, more than a decade after Liberia’s Patrick Sawyer entered the country with the infection.

The female patient who imported the virus had previously travelled to Uganda and developed symptoms after returning to Nigeria. She was born in Uganda and was married to a Swiss diplomat.

The 42-year-old patient tested positive for the Bundibugyo strain of the Ebola virus disease on October 20.

She was evacuated to Switzerland on October 26 to complete her treatment.