The bugs of late summer are biting. The nation is on track toward its worst West Nile virus season since the disease hit America's shores in 1999, health officials say. So far, 1,405 serious illnesses and 118 deaths from West Nile have been reported across the country. Up to 10,000 people who stayed in tent cabins at Yosemite National Park are at risk of hantavirus. A second case of bubonic plague in the West has been confirmed and scientists fear that a bumper crop of ticks could spread Lyme disease, the nation's most common bug-borne malady. Yet the risk of getting these scary-sounding diseases is small. With the right precautions, you can still enjoy spending time outdoors and fight much more common threats to your health — obesity and too little exercise.
How it's spread: Touching or breathing air particles of urine or droppings from certain types of mice or rats, especially deer mice.
Symptoms: Develop one to six weeks later and can include flulike symptoms that progress into a dry cough, headache, nausea and vomiting, then shortness of breath.
Where it occurs: Anywhere in the United States; recent cases were in Yosemite National Park in California.
Prevention: Keep rodents out of your home; carefully clean any nests with disinfectant or bleach and water.
How it's spread: ticks.
Symptoms: fever, headache, fatigue and a bull's-eye rash. Untreated, it can cause joint, heart and nervous system problems.
Where it occurs: Northeast and mid-Atlantic coastal states; north central states, mostly Wisconsin and Minnesota; the West Coast, especially northern California.
Prevention: Use bug repellents with 20 percent or more DEET; when in the woods, walk in the center of trails, avoiding brush; shower soon after coming inside and check your body, hair and clothes for ticks.
(Also helps prevent other tick-borne diseases such as ehrlichiosis, Rocky Mountain spotted fever, tularemia and babesiosis).
How it's spread: mosquitoes
Symptoms: Most people have none; some develop flulike symptoms; a very small percentage suffer neurological symptoms.
Where it occurs: Nearly all states; this year, Texas has been hardest-hit.
Prevention: Eliminate standing water that can breed mosquitoes; use insect repellents containing DEET, picaridin, IR3535 or oil of lemon eucalyptus.
How it's spread: Contact with infected fleas, rodent or cat; prairie dogs in Colorado can carry it.
Symptoms: Sudden fever, headache, chills, weakness and swollen lymph nodes.
Where it occurs: Only about half a dozen cases occur each year across the country, mostly in the Southwest.
Prevention: Avoid contact with rodents; limit brush, rock and wood piles and rodent breeding areas near the home.