ALBANY, N.Y. (CBSNewYork/AP) — State agriculture officials are advising horse owners in New York to vaccinate their horses against West Nile virus.

The Department of Agriculture and Markets says there have been four confirmed equine cases of the mosquito-borne infection in the state this year, in Steuben, Suffolk, Cattaraugus and Livingston counties.

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Infected mosquitoes can pass West Nile virus to humans, horses and other animals. Symptoms can resemble the flu, with horses appearing mildly anorexic and depressed. Other symptoms are muscle and skin twitching, fever, hypersensitivity to touch and sound, drowsiness and unsteady gait.

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Twelve cases of West Nile virus have been reported in humans this year. Most people have no signs of illness but some develop flu-like symptoms. Fewer than 1 in 150 experience serious symptoms.

There is no vaccine for humans.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)