CNA Explains: Why a rare Ebola strain is causing concern and raising vigilance around the world

What does the WHO declaration mean? 

The WHO on May 16 declared the Ebola outbreak in Congo and Uganda an emergency of international concern.

This is the agency’s highest formal alarm under international health law. It is used for extraordinary outbreaks that pose a cross-border public health risk and require a coordinated international response.

The designation does not signal that the current outbreak is expected to become a global pandemic, but it is intended to mobilise funding, technical support and preparedness efforts.

Professor Paul Tambyah, deputy chair of the Infectious Diseases Translational Research Programme at NUS Yong Loo Lin School of Medicine said the declaration will also accelerate the clinical trials of vaccines and therapeutics. 

“These were funded in January this year and can now be field tested in an urgent situation,” he said.

Dr Bhadelia stressed that Ebola does not pose the same global pandemic risk as airborne viruses like COVID-19, as it requires close contact to spread.

The WHO’s declaration was issued partly because this is DR Congo’s 17th Ebola outbreak, she noted, most of which were “handled within a matter of weeks”.

“The trouble with this is that everything about this outbreak so far is telling us that we aren’t discovering a new outbreak, we are just surfacing more details about an outbreak that has been going on for a while, so that’s the number of suspect cases and deaths that we see, but also how widespread it is currently,” Dr Bhadelia said. 

What’s the risk of Ebola spreading to Asia?

As the Ebola virus is not easily transmitted, Prof Oshitani said the risk of a large outbreak in Asia is low, although there could be “sporadic” cases imported into Asia.

“If these cases are not detected quickly, secondary cases among close contacts could occur,” he told CNA.

“However, unlike COVID-19, preventing secondary transmission of the Ebola virus is not difficult. Early detection of potential cases is key to preventing secondary transmission.”

Professor Dale Fisher from the Yong Loo Lin School of Medicine at the National University of Singapore agreed, saying that the risk of someone travelling from the remote northeast DR Congo to Asia with Ebola is very low.

“Furthermore, the disease only transmits by bodily secretions, not respiratory droplets like COVID and flu and only when there are symptoms,” he added.

The disease could, however, go beyond borders if someone travels while incubating the disease and develops Ebola outside Africa. 

Prof Tambyah also said the outbreak is not a major concern for Asian countries as the outbreak epicentres are in rural parts of central and east Africa, where few Asians travel.

“I think it is reasonable to put in additional screening measures for travellers from Uganda and DRC, although the vast majority who arrive in Southeast Asia from either country are likely to be from the major cities far away from the disease zones.”

Prof Tambyah noted that there have only been sporadic cases of the virus identified outside the African continent. 

“Outbreaks in Africa have almost always been in zones of conflict or civil unrest where the local healthcare system is not fully functional,” he said.

“Patients are generally most infectious when they are very ill or dead. These individuals are likely to be too sick to board a transcontinental flight, and hence the risk of distant infection is low.”