The Eastern equine encephalitis virus has been detected in mosquitoes in Massachusetts for the third time this year, this time in nearby Easton, the Massachusetts Department of Public Health said.

A mosquito sample collected in Easton, which borders Norton, showed presence of the disease, the health department said.

Responding to the finding, the Bristol Mosquito Control Project, in collaboration with DPH, will be increasing its mosquito surveillance and control activities in the area.

Earlier this week, the virus was found in mosquitoes in Seekonk, which has led to concerns in neighboring Attleboro.

"We are not currently seeing evidence of the intense EEE activity that occurred over the last few years; however, the virus is clearly present in the environment, and we will continue our surveillance for it," said Dr. Al DeMaria, DPH Director of Communicable Disease Control. "We are asking the public to help protect themselves by taking precautions." EEE had first been found in mosquitoes in Raynham at the beginning of July.

There have been no human cases of EEE detected this season, but last year there were five human cases of EEE, with two fatalities. The disease is usually fatal to about one-third of humans who contract it.

EEE is usually transmitted to humans through the bite of an infected mosquito. The type of mosquitoes that usually carry the virus is found in freshwater, hardwood swamps, such as those found in southeastern Massachusetts, DPH says.

At this time last year, DPH had identified about 19 positive EEE mosquito pools.

However, West Nile virus in mosquitoes is more prevalent so far this summer, DPH officials say.

The illness has been detected in mosquitoes or birds in eight Massachusetts communities this year.

The type of mosquitoes that usually carry West Nile virus are called container breeders, which breed in both natural and artificial pools of standing water such as in rock pools, rain gutters/drains, catch basins, flower pots, bird baths, wading pools and tires.

While there have been no human cases of West Nile virus identified this year, health officials are concerned about the number of mosquitoes they are finding infected with the virus.

"The mosquitoes of concern for potential transmission of West Nile virus are the Culex species. When we compare certain collections to last year, we are seeing more than twice the number of mosquitoes," DeMaria said. "One of the most important things that people can do to help reduce their risk from West Nile virus is to empty anything that collects water in their yard. Water that is allowed to sit there for four days or more can provide places for mosquitoes to breed."

Health officials are urging people to take the following additional precautions: Be aware the peak mosquito hours are from dusk to dawn. Consider rescheduling outdoor activities that occur during evening or early morning. Otherwise, use repellent and clothing that covers arms and legs.

Use screens and repair damaged ones.

More information is available on the DPH Web site, www.mass.gov/dph or by calling the DPH recorded information line at 1-866-MASS-WNV (1-866-627-7698).

Also call that number to report dead crows, blue jays or robins, which may be a sign that WNV is circulating among the birds and mosquitoes in an area.

STEPHEN PETERSON can be reached at 508-236-0377 or at speterson@thesunchronicle.com.