The type of Ebola in the latest outbreak in Democratic Republic of Congo is the Zaire strain which has been successfully vaccinated against in past flare-ups, the health ministry said in a statement on Thursday. There were now suspected cases in the busy nearby town of Beni and the neighboring Ituri province.
Officials say it is not yet clear whether the two Congo outbreaks are linked.
In this week's Ebola outbreak, four cases have been registered in and around the town of Mangina, which has a population of 60,000 and is located near the border with Uganda.
The report of the outbreak, the tenth to hit DRC since it was discovered in 1976, came barely a week after Congo had declared the end to an epidemic in its northwest region.
"It would appear that the risk, as we can surmise for DRC, is high".
The organization's emergency response chief, Peter Salama, expressed concern about the regional risks this outbreak could pose - given the pattern of its spread and its closeness to worldwide frontiers.
Ebola is believed to be transported long by bats and can find its way into bush meat sold at local markets. "She had fever, vomiting, bloody nose and bloody diarrhoea as her final set of symptoms". Ebola is a constant threat in the Democratic Republic of Congo as the virus thrives in heavily forested areas.
The swift vaccinations of more than 3,300 people helped in containing the previous outbreak, which saw 33 deaths.
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If it is the Zaire strain, the Merck vaccine used in the last outbreak may be an option, otherwise the situation will be much more complex "and we may not have any vaccine options", he told Reuters at WHO's headquarters in Geneva.
This latest outbreak poses various challenges for the WHO.
Jasarevic says World Health Organization will work with these neighboring countries to try to prevent the virus from crossing over.
The WHO said the presence of armed groups and the wide-distance spread of the disease, could make vaccination "near impossible" in North Kivu.
Government officials said at least 20 people died in nine days after showing symptoms of haemorrhagic fever in and around the village of Mangina.
The hospital was awaiting help from the Red Cross to bury the bodies properly, she said.
The Ministry has also reactivated surveillance teams and task forces at Uganda's different border points with Congo to control movements and conduct screening for those entering the country.
"We can't at this stage confirm whether they are all confirmed or probable Ebola cases", he added.