The World Health Organization on Wednesday declared the Ebola outbreak in the Democratic Republic of Congo a global health emergency, citing the virus's recent spread into Goma, one of the country's most densely-populated cities.

Two million people reside in Goma, which sits just south of the epicenter of the outbreak, near the border of Rwanda.

Still, the WHO believes that the risk of the virus spreading beyond the region remains low.

 "Our risk assessment remains that the risk of Ebola spread in the Democratic Republic of Congo and the region remains very high, and the risk of spread outside the region remains low," said WHO Director-General, Dr. Tedros Adhanom Ghebreyesus.

The outbreak in Congo has been ongoing for nearly a year, with 2,418 confirmed cases and 1,676 deaths. The WHO estimates 12 new cases are reported daily. It is the second deadliest Ebola epidemic ever.

Controlling the outbreak means public health officials must overcome major obstacles: political and economic instability in Congo's Ituri and North Kivu provinces, as well as continued violence among armed militia groups.

The WHO reports there have been nearly 200 attacks against healthcare workers and patients since January. Wednesday's declaration included advice not to close any borders but could help to increase funding and assistance from other countries.

The last time the WHO declared a global emergency related to Ebola was in August 2014, during the West Africa epidemic, the world's deadliest.

Throughout that epidemic, which lasted from 2014 to 2016, at least 28,000 suspected cases of Ebola were reported, and more than 11,000 people died, according to the CDC. The vast majority of cases were in Guinea, Liberia and Sierra Leone. But cases also stretched into Italy, Mali, Nigeria, Senegal, Spain, the United Kingdom, and the United States.

The West Africa outbreak spurred work toward a safe and highly effective Ebola vaccine. The vaccine is now being used to help control the spread in Congo by vaccinating health care workers and people who have been in contact with Ebola patients, as well as the contacts of those contacts.

The Ebola virus is spread through contact with blood and other bodily fluids. It can cause massive internal bleeding, vomiting, diarrhea, and death. An outbreak often starts with a "spillover event," meaning the virus is transmitted from an animal — usually, a fruit bat or monkey — to a human. Then, the virus can spread from person to person.

There is no cure for Ebola. Doctors use supportive fluids and electrolytes to help counter the side effects of high fever, vomiting, and diarrhea.