The latest Ebola outbreak in the Democratic Republic of the Congo (DRC) has put its neighboring countries on alert with the World Health Organization (WHO) saying tackling the epidemic would be "complex."

On July 24, WHO had declared an official end to the Ebola outbreak in DRC but within a week, the epidemic made a comeback with a fresh case confirmed on Aug. 1.

Preliminary laboratory results indicated a cluster of Ebola cases in the eastern province of North Kivu, some 2,500 km from the far western province of Equateur, where the outbreak was reported and then officially declared to have ended.

However, there was no evidence to suggest a link between the two outbreaks, although it was very likely that they shared the same deadly Zaire strain, Peter Salama, deputy director general of emergency preparedness and response at WHO, said Friday.

"It's going to be a very, very complex operation ... trying to extinguish an outbreak of a deadly high-threat pathogen in a war zone," Salama warned, referring to logistical challenges and the ongoing conflict.

North Kivu shares borders with Rwanda and Uganda with a great deal of cross-border movement due to trade activities.

The province hosts over 1 million people displaced by the violence between ethnic groups in the Ituri region in the northeast.

There is the additional risk that those fleeing violence may head toward nearby countries, taking the infection along, WHO warned, adding that additional surveillance measures are being implemented at crossing points.

Health authorities in Rwanda, Tanzania and Uganda warned citizens to stay calm and take preventive measures.

The Ebola virus is highly contagious and causes a range of symptoms including fever, vomiting, diarrhea, generalized pain and in many cases internal and external bleeding.

This is the 10th Ebola outbreak in the DRC since 1976. A total of 33 cases, including 26 deaths, were reported during the ninth outbreak, according to the Africa Centers for Disease Control and Prevention.