KINSHASA, DR Congo (AFP) — The worst Ebola outbreak ever in the Democratic Republic of Congo (DRC) has passed the 9,000-case mark, with the number of deaths exceeding 4,000 since early October, health authorities said Tuesday.

The DRC officially declared the 17th Ebola outbreak in its history in mid-May, but experts believe the virus emerged weeks or even months earlier.

The outbreak has infected 9,066 people so far and caused 4,381 deaths, a fatality rate of 48.3 per cent, according to a new report from the Congolese National Institute of Public Health.

Ebola, which is transmitted through contact with bodily fluids and causes severe haemorrhagic fever, has claimed more than 15,000 lives in Africa over the past 50 years.

The worst outbreak previously recorded in the DRC caused nearly 2,300 deaths out of 3,500 reported cases between 2018 and 2020.

In the latest outbreak, 2,389 recoveries have been reported.

After starting in Ituri, in the northeast, the outbreak has spread to seven provinces in the north and east.

Health-care resources are limited in these remote regions, where the presence of armed groups makes travel difficult.

Medical workers and humanitarian staff also face distrust from local communities, which has led to several incidents in recent months.

The current outbreak is caused by the Bundibugyo strain of the virus, for which there is currently no approved vaccine or treatment.

Initial doses of the Ervebo vaccine, whose effectiveness has been proven against the Zaire strain — the most common variant in the past — have been administered in recent weeks to frontline volunteers as part of a clinical trial.

A clinical trial for an Ebola vaccine is expected to be launched in the DRC before the end of the month, experts from the World Health Organization said on Tuesday.