U.S. health officials say the country has just had its worst year ever for West Nile virus.

The U.S. Centers for Disease Control and Prevention says that so far, 118 people have been reported dead and more than 1,400 seriously ill from the virus. The agency's Dr. Lyle Peterson says the southern state of Texas has been the most severely affected.

“Two-thirds of all cases have been reported from six states: Texas, Louisiana, South Dakota, Mississippi, Michigan and Oklahoma. And 40 percent have been reported from Texas.”

Dr. Petersen says the number of cases is up 35 percent from last week, but that the virus probably has peaked.

The CDC says that since the virus first hit North America in 1999, more than 30,000 people in the United States have been reported as getting sick with West Nile virus, which is spread by mosquitoes.

The sometimes deadly virus can cause neuroinvasive diseases, such as meningitis or encephalitis. In milder cases it can cause fever, abdominal pain and diarrhea. There is no vaccine to protect people from the virus.