(CBS News) The Centers for Disease Control said Wednesday that the current outbreak of the West Nile virus in America may be the worst ever.
Cases are reported in 47 states. More than 1,100 people have been infected and 41 have died.
No state has seen more cases than Texas.
In the summer of 2005, John Shaw's life changed forever from a mosquito bite.
"A couple of days later I was getting dressed and I put on my shorts and I just collapsed," Shaw said. "I couldn't walk hardly, I couldn't stand up. I climbed down the stairs on my hands and knees."
The 59-year-old spent two weeks in the intensive care unit with inflammation of the brain and nervous system.
"The doctor came in and he jokingly said, 'yeah, we're even gonna test you for West Nile,'" Shaw said.
Shaw tested positive and ended up in a wheelchair. He still suffers from leg paralysis seven years later.
Dr. Kristy Murray has been studying west Nile since the first U.S. outbreak in 1999. She found that the virus remains in the body for about a third of patients -- like Shaw, with severe illness. Their symptoms can become chronic.
"It's incredibly surprising. It's not what the textbooks say about West Nile at all," Murray said.
About one in 150 patients infected with the West Nile virus become seriously ill. Of those, about 60 percent have long-term effects including fatigue, blurred vision, trouble thinking, kidney disease and paralysis.
The current outbreak is likely occurring because of a combination of a mild winter followed by a soggy spring -- perfect conditions for breeding mosquitoes.
"Eighty percent of our cases occur between August and September. So we're just still kind of that beginning of how this is going to end up playing out," Murray said.
John Shaw has built a new life for himself and now runs his travel agency from home. He doesn't complain, but if pressed, does admit one thing.
Shaw said he misses "taking a walk."
There is currently no effective anti-viral treatment for West Nile. An effective vaccine for horses has existed for about ten years, but Dr. Murray told me there hasn't been enough demand for one to be developed in humans.