An outbreak of the deadly Ebola virus that has already claimed thousands of lives is ratcheting up the death count.  According to the World Health Organization (WHO) the death toll from the Democratic Republic of Congo’s year-long Ebola outbreak has climbed above 2,000.  The outbreak – one of the worst ever recorded of the devastating virus – continues to spread, as medical responders battle to overcome community mistrust and widespread security problems.

The death reported last week, of a 9-year-old girl in neighboring Uganda, who had tested positive for the virus after entering the country from Congo, underscores the challenge medical teams face containing the disease in border territory with a highly mobile population.

The government team overseeing the medical response to the deadly epidemic said the number of confirmed and probable cases had also hit a milestone of more than 3,000. That figure has made this the second-worst epidemic of the virus on record, and if responders cannot gain some control soon, it is poised to become the worst ever.

Despite the development of an effective vaccine and treatments, health workers have struggled to stop the virus spreading in remote and conflict-hit areas of eastern Congo, where many locals are wary of the response effort.

Nevertheless, the World Health Organization said the latest Uganda case highlighted the border authorities’ skill at detecting and isolating potential sources of transmission.

“This case was picked up at the border,” WHO spokeswoman Fadela Chaib said at a briefing in Geneva. “The people who are at the borders have the expertise.”

An International Health Emergency

This is Congo’s 10th Ebola outbreak, but it is the first in the densely forested hillside provinces of North Kivu and Ituri, where militia-led violence and ethnic killing have undermined security in certain areas for decades.

The WHO declared the epidemic an international health emergency just this past July – only the fifth outbreak to warrant this status since the system was introduced in 2005.

The authorities have since come up against new fronts in their fight to contain the virus, testing the reach and flexibility of responders.

Health workers confirmed the first cases in South Kivu province on Aug. 16. Soon after, a woman contracted the virus in a remote, militia-controlled territory in North Kivu, hundreds of kilometers away from other known cases.

“The response is being spread too thin chasing new cases at the expense of the longer-term community engagement that is crucial if we’re ever to hope of being Ebola-free,” Oxfam’s Congo Director Corinne N’Daw said in a statement.

Despite the virus spreading to new areas, the past week’s transmission rate was little changed from that of the past month and a half, which has seen an average of 77 new cases per week, according to the WHO.

Only the 2013-2016 Ebola outbreak in West Africa has been deadlier than the current outbreak. More than 11,300 people died then out of the 28,000 who were infected.

Ebola is a rare but deadly virus that causes fever, body aches, and diarrhea, and sometimes bleeding inside and outside the body.

As the virus spreads through the body, it damages the immune system and organs. Ultimately, it causes levels of blood-clotting cells to drop. This leads to severe, uncontrollable bleeding. It kills up to 90% of people who are infected.