The death toll from Lassa fever in Nigeria has risen to 41 as cases are being confirmed in more regions, Nigeria’s disease control agency said.

The Nigeria Centre for Disease Control (NCDC) said on Tuesday that from January 1 to January 26 a total of 258 confirmed cases, including five health workers, were reported across 19 states.

The latest figures marked an increase from 29 deaths and 195 confirmed cases given by the authorities for the period up to January 24.

Endemic to Nigeria, Lassa fever belongs to the same family as the Ebola and Marburg viruses, but is much less deadly.

The virus is spread by contact with rat faeces or urine. It starts with fever and can, in worst-case scenarios, lead to severe bleeding and organ failure.

Nigeria declared an outbreak of Lassa fever a year ago and around 170 people died from the virus in 2019.

The number of cases usually climbs in January due to weather conditions during the dry season.

The NCDC said that the fatality rate was down to 15.9 percent from 19.7 percent during the same period last year.

The agency said although there has been a spike in the number of deaths reported for the week, the figure is still lower than the 42 deaths reported in January 2019.

The NCDC said at the weekend that it had activated a national emergency operations centre to coordinate the response “to the increasing number of Lassa fever cases” across the country.

The name of the virus comes from the town of Lassa in northern Nigeria where it was first identified in 1969.