KNTV NBC Nightly News With Lester Holt September 10, 2019 09:18:00
This is one of the most deadly mosquito-born infections. >> reporter: eee is rare but comes with a 33% fatality rate. the numbers of human cases nearly doubling from last year, 11 confirmed so far this season including seven in massachusetts. within days, symptoms can go from headache and fever to brain swelling and coma. 14-year-old savannah neigan >> her brain is trying to heal itself and she can't do anything until that happens. >> reporter: experts say with no known treatment, your best option, protect yourself keep windows closed and when outside, wear bug spray with deet and cover up dur...