Kampala, Uganda — The Ebola outbreak in the Democratic Republic of Congo and neighboring Uganda is still spreading one month after the outbreak was declared. The total number of confirmed cases surged between Monday and Tuesday to over 800, an increase of about 300 since last week. 

The United Nations' World Health Organization has warned that the virus is still "increasing" in its "geographic spread" in Congo, and experts say it's a race against time to stop it from mushrooming into a wider health crisis. 

In the epicenter of Ituri province, Congolese security forces fired warning shots to break up an angry crowd of people trying to take the body of an Ebola victim home. Health workers were trying to remove the body for the community's safety — even in death, victims are highly contagious.

The WHO has said that "intense community transmission continues" in the Central African region, and new cases and deaths have surged.

WHO Incident Manager Dr. Marie-Roseline Belizaire told CBS News deaths were still being reported by the community in Congo, and "that means we are missing cases," with the disease still spreading undetected in the population.

"One month after the outbreak has been declared, I'm still feeling concerned," she said.

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Efforts to trace anyone believed to have come into contact with known Ebola cases have also seen slow progress. There's been some improvement, but Congolese health workers say they've only been able to follow up with a little over half of the people who came into contact with confirmed cases. In real numbers, this means about 3,000 possible contacts are still unaccounted for.

Over the border in Uganda, authorities are in proactive protection mode. As soon as CBS News landed in the country, all members of the team had to scan a QR code and declare that nobody had been in contact with bats, attended a funeral or experienced symptoms of Ebola such as fever or vomiting.

But that was at the main airport. Uganda shares a nearly 500-mile border with Congo — about the length of the state of Florida — and despite it officially being closed amid the outbreak, people continue to move freely across it.

"Our problem is how is it being managed across the border with the Congo," Uganda's National Director of Public Health, Dr. Daniel Kyabayinze, told CBS News. "We know all our cases have been imported from there."

As of June 10, the WHO said at least 19 Ebola cases had been confirmed in Uganda, including two deaths.

Kyabayinze said the movement of people across the border was likely "very minimal" under the restrictions, but he couldn't rule it out. 

"We are the same people. The culture and language in Uganda and the people across the Congo are the same," he said. "They're the same families. So, even when you have non-gazetted (unofficial) crossing points, the families still communicate."

"Putting a tight ribbon, or a no-stop movement on the porous borders is almost impossible, it's like stopping wind from blowing," Kyabayinze said.

He and other top epidemiologists told CBS News this week that they're generally happy with the preventative measures implemented by Uganda, and no new cases have been reported in the country in 11 days. But they said they continue to monitor the outbreak in Congo — and the two countries' long shared border — very closely.