At least 101 people have been killed by the largest outbreak of Lassa fever in Nigeria, humanitarian aid organization Medecins Sans Frontieres (MSF) said Monday.
More than 400 people have been infected with the dangerous virus since the outbreak began in January and spread across 18 states in the West African nation, MSF said in a statement.
Most affected are the states of Bauchi in the north-east, Ebonyi in the south-east and Ondo in the south-west, according to MSF.
Among the infected and killed are also health workers who treated patients, said MSF.
Although Lassa fever - an acute viral haemorrhagic illness that is often fatal - is endemic to Africa's most populous nation of more than 190 million people, it is the first time that so many people have been infected with the virus, according to Nigeria's National Centre for Disease Control (NCDC).
In late February, the NCDC had recorded 317 infections and 72 deaths.
Hundreds of people who came into contact with those infected are under observation, the NCDC said.
Lassa fever is transmitted to humans from contact with food or household items contaminated with rodent excreta.
The disease is also spread between humans through contact with the blood, urine, faeces or other bodily secretions of an infected person.