Baku, March 22, AZERTAC The death toll of Lassa fever has risen to 128 in Nigeria, Africa's most populous country, since the beginning of this year, Xinhua reports citing public health authorities.The 128 fatal cases were among a total of 682 confirmed cases from the outbreak of viral hemorrhagic fever recorded since January, according to the Nigeria Center for Disease Control and Prevention (NCDC) in its latest report.At least 20 fatal cases were recorded across 16 out of Nigeria's 36 states within one week, precisely from Feb. 26 to March 3 alone, the NCDC said, noting the severity of the outbreak with a case fatality rate of 18.8 percent.The public health agency said the predominant age group affected is 31 to 40 years of age, adding that the male-to-female ratio for confirmed cases is 1:0.9.Lassa fever is a disease spread to humans through food or household items contaminated with rodent urine or feces. It is reportedly transmitted when saliva, urine, and the excreta of rats come into contact with humans.