The Centers for Disease Control and Prevention released its final 2012 national surveillance data for West Nile virus activity for the United States at www.cdc.gov/westnile.
Texas reported 33 percent of all reported West Nile virus cases in 2012. The other top states were California, Louisiana, Michigan, Mississippi, Oklahoma and South Dakota.
Forty-eight states reported a total of 5,674 cases of West Nile virus disease in people, including 286 deaths to the CDC. Of all West Nile virus disease cases reported, 51 percent were classified as neuroinvasive disease including: meningitis, encephalitis, or acute flaccid paralysis. The dates when the patients' illness began ranged from March through December 2012.
The numbers of neuroinvasive, non-neuroinvasive and total West Nile virus disease cases reported in 2012 were the highest since 2003 and the number of deaths was the highest since cases of the disease were first detected in the United States in 1999, the CDC said.
Last summer's outbreak most likely resulted from many factors, including higher-than-normal temperatures that influenced mosquito and bird abundance, the replication of the virus in its host mosquitoes and interactions of birds and mosquitoes in hard-hit areas, the CDC said.