At least 41 people have died from West Nile virus in recent weeks, in the worst outbreak of the disease since the virus was first detected in the United States in 1999, the Centers for Disease Control and Prevention (CDC) said Wednesday. Last week, the nation's death toll stood at 26. The number of most severe infections - those that cause encephalitis or meningitis - rose 55 per cent in just one week. According to dpa, worst hit is Texas, which has reported 21 deaths from the mosquito-borne disease. The state's official tally will likely rise to 25 when another four suspected deaths are confirmed, Texas state Health Commissioner David Lakey said in a telephone briefing with reporters. Mississippi, Louisiana, South Dakota and Oklahoma account for most of the other deaths.