This is now the worst year on record for the West Nile virus in Texas since the illness was first detected 13 years ago, according to the state's department of health services.
The number of cases in the United States recently jumped 25 percent, and nearly 2,000 cases have now been reported in 2012.
The cases have increased the most in the northern United States, with 44 states having at least one human infection, according to Dr. Lyle Petersen, director of the division of vector-borne infectious disease at the Centers for Disease Control and Prevention.
At least 87 people have died as a result of the virus, including 43 people in Texas.
Mosquitoes get West Nile from feeding on infected birds then spread the virus through their bite.
Most people who get the virus don't show any symptoms.
"Even if West Nile virus transmission were to stop today, we would continue to see reports of cases for several weeks," Petersen said.
But symptoms include headaches or fever, and more severe cases can lead to neurological problems or brain damage, including a coma, convulsions, and paralysis.
Texas is working to keep the mosquito problem under control with aerial sprays.
Department of State Health Services Commissioner Dr. David Lakey said in areas that received two consecutive aerial sprays, the number of mosquitoes decreased by 93 percent.