Abuja, Apr 14 (IANS): Nigeria recorded four more Lassa fever deaths in the past week, raising the death toll to 148 since the beginning of the year, health authorities said.

In its latest update on the Lassa fever outbreak in the country, the Nigeria Centre for Disease Control (NCDC) said on Thursday that the viral hemorrhagic fever has spread to 25 states so far, with a total of 846 confirmed cases and 4,338 suspected cases since January while the case fatality rate stood at 17.5 per cent, Xinhua news agency reported.

According to the WHO, 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 faeces 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.