Maryland health officials are cautioning Eastern Shore vacationers and residents that an often-fatal brain virus transmitted by mosquito bites has caused two horses to be destroyed since July.

The first human case of eastern equine encephalitis since 1982 was reported last year, but no people have contracted the disease so far this year, according to the Maryland Department of Health and Mental Hygiene.

The state is expanding aerial and ground spraying of mosquito-infested areas of the Eastern Shore to destroy the disease's carriers. The state also is advising people to protect themselves from mosquito bites by wearing long-sleeved shirts and long pants, using insect repellents and eliminating standing water sites which serve as mosquito breeding grounds.

The state also advises that window and door screens be kept in good repair and suggests people avoid the outdoors during peak mosquito times of dusk and early evening.

"Sleeping sickness" symptoms in people include fever, confusion, headaches, and convulsions.

A Wicomico County pony was euthanized July 13 and an autopsy found it had the virus. A Cecil County horse infected with the virus was destroyed Aug. 7 after refusing food and water, walking into walls and circling for one day, according to the state health department.