After the second outbreak of the current mystery disease began in the town of Bomate on February 9, samples from 13 cases have been sent to the National Institute for Biomedical Research in Congo's capital, Kinshasa, for testing, the WHO said.
According to the WHO's Africa office, the first outbreak in the town of Boloko began after three children ate a bat and died within 48 hours following hemorrhagic fever symptoms.
An unknown illness has killed more than 50 people within hours of the onset of their symptoms in northwestern Congo, according to the World Health Organization.
Last year, another mystery flu-like illness that killed dozens of people in another part of Congo was determined to be likely malaria.
Doctors on the ground say the interval between first symptoms and death has been 48 hours in the majority of cases.
