Confirmed Ebola cases in the Democratic Republic of the Congo have passed 9,000, government data showed Tuesday, according to the Associated Press and Reuters.

The latest report put the total at 9,066 confirmed cases and 4,381 deaths, Reuters reported, as published by CNBC Africa. That means nearly half of known cases have died, the AP said, as published by Al Jazeera.

The outbreak is caused by the Bundibugyo strain of Ebola. It has become the largest and deadliest in Congo's history, both outlets reported. Reuters said it has overtaken the 2018-2020 epidemic.

Around the world, only the 2014-2016 outbreak in West Africa was bigger, both outlets said, citing the World Health Organization. That outbreak infected more than 28,600 people and killed more than 11,000 in Guinea, Liberia and Sierra Leone.

The Bundibugyo strain has no approved vaccine or treatment, both outlets reported. A trial to test how well a vaccine works against it is being prepared in Congo for the coming weeks, a WHO official said Tuesday, according to the AP.

The outbreak was declared in May, both outlets said, though the AP reported that some experts think it began as early as February. It has spread to seven provinces in the north and east, the AP said.

Responders are struggling to slow transmission in several hotspots, Reuters reported. The AP said health workers face mistrust in some communities, where many people believe the disease is a scheme for officials to take money. Fighting between the M23 rebel group and government forces has also made it harder to move supplies to remote areas.

The virus has crossed borders, too. Last week Kenya confirmed its first imported case, a Kenyan man who traveled from Congo through Uganda and died in Nairobi, both outlets reported.

What we know: Congo has confirmed 9,066 Ebola cases and 4,381 deaths.
What we don't: When the vaccine trial will start, or how soon the spread can be slowed.