ABUJA, March 28 -- The death toll from Lassa fever in Nigeria has risen to 142 since the beginning of the year, local health authorities in the most populous African country said Tuesday.

In its latest update on Lassa fever, the Nigeria Center for Disease Control (NCDC) said the viral hemorrhagic fever has so far spread to 23 states, with a total of 784 confirmed cases since January.

Amid intensified measures by the government to reduce infections, the NCDC put the case fatality rate at 18.1 percent, saying at least 97 out of the country's 774 local government areas had so far recorded at least one confirmed case this year.

According to the World Health Organization, Lassa fever is caused by the Lassa virus. Humans usually contract the virus through exposure to food or household items contaminated by the urine or feces of infected Mastomys rats. The disease is endemic in the rodent population in parts of West Africa.

In some cases, Lassa fever has similar symptoms to malaria, appearing between one and three weeks after exposure to the virus. In mild cases, the disease causes fever, fatigue, weakness and headache.

  - Xinhua