For the second time this summer, the Massachusetts Department of Health has detected the presence of West Nile virus in mosquitoes collected in Edgartown, health agent Matt Poole said Friday.

The mosquitoes were collected as part of a regular weekly surveillance program in the cemetery area of Edgartown. Positive tests were returned on Tuesday, July 26 and again on Tuesday, Aug. 16, Mr. Poole said.

“It’s pretty much a certainty that you will get one or more each summer,” Mr. Poole said. “We’ve had cases in Veterans Memorial Park in Vineyard Haven in past years, but Edgartown has not had one for a while.”

“It is a little surprising in this incredibly dry, crunchy summer that we’ve been able to catch enough mosquitoes to constitute a pool, which is five,” he added.

West Nile Virus is a potentially dangerous disease most commonly transmitted to humans by the bite of an infected mosquito. There have been no human cases of the West Nile on the Island, and none this year in Massachusetts. A total of 40 confirmed instances of infected mosquitoes have been found statewide in 2022.

While the virus can infect people of all ages, those over the age of 50 are at higher risk for severe infection, according to the DPH.

Mr. Poole said people should exercise common sense precautions to guard against mosquito bites, including covering up, applying mosquito repellent, using window screens and considering moving indoors during the peak biting hours between dusk and dawn.

The Island’s public health biologist, Patrick Roden-Reynolds, said in a phone interview that he sets traps weekly in all six Island towns in an effort to collect mosquitoes for testing.

The mosquitoes are sorted by species and, if he is able to collect at least five, the group is frozen and sent to the state for testing. Both instances of West Nile were in Culex pipiens mosquitoes, the Island’s native species.

Local officials do not currently test for the presence of eastern equine encephalitis virus (EEE), because they have been unable to source appropriate traps, said Mr. Poole. He said surveillance testing is strongly recommended, but not required by the state.

Mr. Poole said local health officials used to send dead birds to the state labs for testing, but the state has found trapping mosquitoes to be more efficient. Still, sick birds can be a sign the disease is present.

“When people see a sick crow, it is a good likelihood" that West Nile is the cause of death, he said.