WASHINGTON - The U.S. Centers for Disease Control and Prevention (CDC) announced on Wednesday that a total of 2,636 cases of West Nile virus, including 118 deaths, had been reported across the country as of September 11.

A week ago, 1,993 Americans were confirmed infected with the virus, including 87 deaths, CDC officials told a telebriefing.

The disease has been reported in people, birds or mosquitoes in 48 U.S. states, so far absent only in Alaska and Hawaii. Texas accounted for about 40 percent of all human cases. Two-thirds of the cases have been reported from six states -- Texas, Louisiana, South Dakota, Mississippi, Michigan and Oklahoma.

The worst year for the mosquito-borne disease in the U.S. was 2002, which saw nearly 3,000 severe cases and 284 deaths, according to the CDC.

West Nile virus is transmitted to people by infected mosquitoes. In the United States, most people are infected from June through September, and the number of these infections usually peaks in mid-August.

Approximately one in five people who are infected with West Nile virus will develop symptoms such as fever, headache, body aches, joint pains, vomiting, diarrhea, or rash. Less than one percent will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues). About 10 percent of people who develop neurologic infection due to West Nile virus will die. There are no medications to treat, or vaccines to prevent, West Nile virus infection.

According to the CDC, the best way to prevent West Nile virus disease is to avoid mosquito bites: use insect repellents when you go outdoors; wear long sleeves and pants during dawn and dusk; install or repair screens on windows and doors; use air conditioning.