Schools in Stamford canceled after-school activities Friday out of extreme caution after mosquitoes tested positive for eastern equine encephalitis.

State health officials say people who plan to be outside around dusk should keep their skin covered and use bug spray.

MORE: Stamford mosquitoes test positive for EEE
MORE: Third person dies of EEE in Connecticut, fourth diagnosed

Dr. Asha Shah, with Stamford Hospital, says symptoms of EEE include fever, headache, malaise and vomiting. She says the chance of contracting the virus that causes a brain infection is extremely low, but it can be fatal.

Four people have gotten the virus in Connecticut and three have died from it.

Health officials say outdoor events don't need to be canceled unless they are at dusk or dawn.

Mosquito control companies have been extra busy this year because of the outbreak.

"One customer said 'thank you so much, thank you for helping me calm my anxiety,'" said Scott Shaw of Mosquito Joe.

This is the first time a mosquito has tested positive for EEE since 2003.

Health officials say people can eliminate mosquito breeding sites by emptying stagnant water. Shaw says falling leaves can cause gutters to remain filled with water and create breeding ground for mosquitoes.