Photo courtesy of Dr. Bruce Cropp from the Centers for Disease Control, Division of Vector-borne Infectious Diseases. West Nile Virus and its similar diseases are distributed around the world. WN virus is new to the Western Hemisphere, but St. Louis encephalitis has been in the United States for decades. Natural History of West Nile Fever, cont. Aseptic meningitis or encephalitis.
Many cases have only fever with head ache.
Can progress to focal paralysis, intractable seizures, coma and death Infected mosquitoes are the primary source for West Nile virus. Although ticks infected with West Nile virus have been found in Asia and Africa, their role transmission and maintenance of the virus is uncertain. Although the vast majority of infections have been identified in birds, CDC has received reports of WN virus infection in horses, cats, bats, chipmunks,skunks, squirrels, domestic rabbits, and raccoons. Following transmission by an infected mosquito, West Nile virus multiplies in the person's blood system and crosses the blood-brain barrier. Natural History of West Nile Fever, cont.