Tanzania is among six African countries on high alert following an outbreak of Ebola in Guinea on February 14 and the Democratic Republic of the Congo (DRC) a week earlier.
The confirmed cases this time have been reported from the southeast of Guinea about 800km by road from the capital, Conakry, but only about 100km from various border points with Liberia and Côte d'Ivoire.
Sierra Leone and Liberia neighbouring Guinea in West Africa and Tanzania which neighbours the DRC are some of the countries which the WHO has alerted over the Ebola outbreak.
The natural transmission cycle of the virus involves certain species of forest-dwelling fruit bats.
Ebola-infected animals such as non-human primates, monkeys and antelope have been reported before and could present a source of exposure to humans.
"We have already alerted the six countries around, including of course Sierra Leone and Liberia, and they are moving very fast to prepare and be ready and to look for any potential infection," WHO's Margaret Harris said from Geneva.
What sets this outbreak apart is that it is happening against the backdrop of the Covid-19 pandemic, which has health-care and other resources around the globe under severe pressure.
WHO has mobilised and deployed more than 100 staff to tackle new Ebola outbreaks in Guinea and the DRC.
"With experts and emergency supplies already getting on the ground, the response is off to a strong start," said Dr Matshidiso Moeti, WHO Regional Director for Africa.
Ebola infects humans through close contact with infected animals like chimpanzees and fruit bats. It then spreads between humans by direct contact with infected blood, fluids, and organs.
It is the first Ebola outbreak in Guinea since 2016 when more than 11,000 people died in the West Africa Ebola epidemic, which began in Guinea.
"Collective, quick action is crucial to avert uncontrolled spread of Ebola amid the Covid-19 pandemic which has already pushed health workers and health facilities to the edge," said Dr Moeti,
WHO has already ordered a consignment of more than 11,000 doses of Ebola vaccine in Guinea.