The US Center for Disease Control (CDC) has received reports of 1,590 cases of the West Nile virus, including 66 deaths, from 48 US states in August 2012.
The disease, for which there is no available treatment, has infected people, birds and mosquitoes across the country.
The updated figures represent a 40% increase in the number of cases over last week’s report of 1,118 total cases.
In a teleconference, CDC vector-borne infectious diseases division director Dr Lyle Petersen said 43 states have reported at lease one human case of the disease and only Alaska and Hawaii have reported no West Nile virus activity.
Of the cases reported, 56% were classified as neuroinvasive diseases, such as meningitis or encephalitis, and 44% were classified as non-neuroinvasive.
More than 70% of the cases have been reported from Texas, South Dakota, Mississippi, Oklahoma, Louisiana, and Michigan.
Worryingly, only 2 to 3% of cases of West Nile fever are reported to health officials which suggests that the actual number of cases is 30 to 50 times higher than reported.
Petersen advised that the CDC cannot accurately predict how many human cases will be reported this year.
Petersen said; “However, based on current reports, we think the numbers may come close to or even exceed the total number reported in the epidemic years of 2002 and 2003, when about 3000 cases of neuroinvasive disease and more than 260 deaths were reported each year.”
“In light of the ongoing risk for West Nile virus infection, it’s important for people to protect themselves from mosquito bites,” Petersen added.
Texas Department of State Health Services commissioner Dr David Lakey, who has seen the number of confirmed cases of the virus soar to 894 in his state, with 34 people dead, commented on the outbreak.
“Texas as we’re working through the major outbreak and the media for their involvement. They have been critical to getting the key to getting the message out in the state of Texas,” Lakey said.
“One of the issues that a lot of people [have raised, is] have we peaked in Texas or not? At this time, as I look at the data, I’m not convinced we have peaked.”