The United Nations' World Health Organization significantly scaled back on Tuesday the number of suspected Ebola cases in central Africa, lowering it to 116 from more than 900, with 330 total cases confirmed.

The WHO said that as of May 31, there were 116 suspected cases of the deadly virus registered in Democratic Republic of Congo — a massive reduction from the 906 that had been on the books late last week. 

In total, there were 321 cases confirmed in the DRC, including 48 people who had died, while neighboring Uganda had nine confirmed cases, including one death.

While some suspected cases have been confirmed, many more "have been cleared out" after being shown to be other diseases or an unlinked fever, WHO spokesman Christian Lindmeier told reporters Tuesday at the agency's headquarters in Geneva.

While the less daunting caseload may help, doctors working on the front lines of the outbreak say they likely should have learned about it much earlier, and they stress that there are still many challenges to reigning it in.

The International Rescue Committee charity told CBS News the current outbreak may have been spreading, undetected, as early as January.

Dr. Abdou Sebushishe, a medic working with the International Medical Corps in the DRC's eastern city of Goma, told CBS News that workers trying to track down and speak with people who had come into contact with Ebola patients were only managing to reach about a quarter of those contacts. He said when contacted, some people said they believed Ebola didn't even exist.

"Instead of coming to healthcare services, they take alternative solutions with traditional healers or other alternatives, and contribute further to spread the outbreak," he told CBS News. "My message is that Ebola is real." 

He believes it could be "beyond six months before this outbreak could be put under control."

"I think the outbreak is outpacing the current response, and there are adjustments being made to catch up," he said, noting that medics like him still need more resources, including basics like protective gear, to "scale up the protection of healthcare workers." 

Sebushishe added that 20% of all new positive cases were healthcare workers.

But there's rising hope this week that the Ebola strain behind the deadly outbreak can be beaten, even by people who catch the virus. Five front-line nurses who contracted the disease while treating patients have recovered and been declared Ebola-free.

"I called the team and told them, 'Something's wrong here,'" nurse Etienne Ezo said. "I decided to rest for a bit, and a few minutes later I started vomiting."

But she was among the medics handed Ebola survivor certificates this week by visiting WHO chief Dr. Tedros Ghebreyesus.

"Coming out of this illness alive is an indescribable joy," said Baraka Bulambulu, another recovered health worker.

Tedros said testing, treatment capacity and trust in health workers all still needed to improve, but he stressed that, "if you come early, and if you get the medical care support, as others have survived you can survive as well."