The Mosquitoes Are Out. Here’s What to Know About West Nile Virus.

One evening in July 2003, Dr. Lyle Petersen stepped out of his home in Fort Collins, Colo., to pick up the mail. He ended up staying out longer than expected to chat with his neighbor. But when they both got being bitten by mosquitoes, they rushed back indoors.Three days later, Dr. Petersen began to feel extremely fatigued. He developed a fever and a severe headache, and his muscles began to ache. “I was in bed…