Boston-area health officials have raised the risk of West Nile Virus from low to moderate after areas of West Roxbury, Hyde Park, and Roslindale tested positive for for the potentially deadly disease.

So far, there have been no human cases of the virus this year.

West Nile Virus is just one of many to be transmitted through a bite from an infected mosquito.

Eastern Equine Encephalitis or EEE is also a mosquito borne virus and is at high risk for transmission during this time period. However, officials have concluded from recent tests that EEE has not been spotted in Boston’s mosquitoes.

“As part of our surveillance for mosquitoes we have contractual services with our mosquito contractor who has jurisdiction in Boston and our county as well as with the state department," said Pat Maloney, Chief of Environmental Health and Inspectional Programs for the Brookline Department of Health.

"We put out mosquito monitoring stations and routinely test them on a weekly basis that looks for WNV and EEE. When we find [infected mosquitoes] it raises the alert levels for the community to remind everyone that they are now in our location and that you need to take appropriate protective steps," Maloney said.

In addition to regular testing, each community’s public health department is treating towns with larvicide. Larvicide is a growth regulator that can prevent mosquitoes from developing into WNV carrying adult mosquitoes.

Residents can protect themselves by limiting their activities between dusk and dawn, avoiding swampy areas, and wearing long sleeve shirts, pants, and socks. According to health officials, DEET is the best repellant for adults while the CDC recommends certain items for children such as repellents that contain oil of lemon eucalyptus.

Maloney stated that the Brookline Public Health Department was “not surprised” when the outbreak occurred.

“This is something throughout the state that we prepare for," he said. "We have meetings prior to the summer season and we know this is going to be happening. To the degree of how early it happens and what magnitude, the prior weather does have an impact. With a lot of the snow and the snowmelt it does have a contributing factor to mosquitoes being in our populations. Hospitals also monitor people who are admitted and do check for EEE and WNV and when we start seeing it in person it really does raise the level of concern."

Individuals infected with WNV can experience mild flu like symptoms and will recover on their own. There is currently no treatment for both EEE and WNV. Persons over 50 have the highest risk for severe symptoms such as high fever, muscle weakness, and neck stiffness

Questions? Brookline Public Health has set up an information line: (617) 730-2295.