Another challenge is mistrust among some communities. An Ebola burial team was reportedly attacked this week in South Kivu province, forcing responders to abandon a coffin and raising fears of further transmission.
Traditional burial practices often involve washing and touching the body, and funerals typically draw large crowds – all high risk for Ebola, which is spread from one person to another by contact with infected bodily fluids.
Tedros said building trust with communities was critical to bringing the outbreak under control.
The Ebola outbreak is concentrated in three provinces of eastern DR Congo, an area roughly the size of the United Kingdom, much of it rural, remote and difficult to reach.
It is also unfolding in one of the most volatile regions in Africa, with many armed groups operating.
The latest outbreak is caused by the Bundibugyo species of Ebola, which has only occurred twice before. Because it is much rarer than other types of Ebola, there is no vaccine or proven treatment, although various teams are trying to develop them.
Speaking on the BBC’s Today programme, Tedros said that earlier this year he had urged foreign ministers planning to increase defence spending not to forget about the “invisible enemy”.
He said the Covid pandemic had resulted in around 20 million deaths – far more than any recent conflict.
However, he stressed that he did not expect Ebola to spread worldwide because the virus is not airborne, unlike coronavirus.
The WHO assesses the risk from Ebola as very high within DR Congo – this is the 17th outbreak in the country where it was first discovered 50 years ago – high in the region, but low globally.
On Friday, US Centers for Disease Control and Prevention said its model scenarios showed that without strong public health intervention the current outbreak could become as large – or even larger – than the outbreak in West Africa in 2014-16.
Separately, the US said it would provide an additional $38m (£28m) for Ebola “response efforts”, bringing the total direct funding to more than $200m.
Earlier this week British government officials said they had ruled out introducing temperature checks at UK airports for flights arriving from affected regions because of their limited effectiveness.
More than 12,000 passengers were screened at five UK airports during the 2014 outbreak in West Africa, but these failed to pick up the only case, that of nurse Pauline Cafferkey.