Health officials are warning western Connecticut residents to be wary of mosquitos after three cases of West Nile encephalitis were reported in Danbury, Newtown and Greenwich.

They say two adults from Newtown and Danbury were confirmed to have contracted West Nile virus in August and are recovering. A Greenwich resident in their 70s was also hospitalized with encephalitis at the end of last month.

Infectious disease doctors say seniors tend to present more serious symptoms with West Nile virus, including behavioral changes that go along with brain swelling.

State officials say mosquitos remain a concern until the first hard frost of the year.

Since 2000, Connecticut has reported 160 West Nile infections that resulted in four deaths.