The number of U.S. cases of West Nile virus rose by 19 percent in the latest week, slowing slightly from its earlier pace but still putting this year on track to be the worst outbreak since 2003, government figures showed on Wednesday.

So far this year, 3,142 cases have been reported to federal health officials as of September 18, up from 2,636 reported the week before, the Centers for Disease Control and Prevention said in its weekly update of outbreak data.

While still a sharp rise, the rate has slowed somewhat. Earlier this month, the number of cases jumped by more than 30 percent in one week.

Almost 40 percent of all cases have been reported in Texas. Other states with large number of cases include Mississippi, Michigan, South Dakota, Louisiana, Oklahoma, and California.

A total of 134 people have now died from the disease, compared with 118 reported one week ago.