DENVER -- More cases of West Nile virus have been found in Colorado.

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The blood of two magpies tested positive this past week. One was in Larimer county near Timnath and the other was near the town of Crowley in southern Colorado. The virus was also found in a mosquito pool near Boone in Pueblo County, health officials said.

These are the first new cases of West Nile virus reported in Colorado since an infected bird was discovered 10 days ago. The results of the test on that first magpie, which marked the return of West Nile virus to Colorado this year, were released on Tuesday, June 17. That magpie was found southeast of Penrose in Fremont County.

West Nile virus was first identified in Colorado in mid-August 2002 when the virus was detected in two horses and a crow from Weld County and one horse from Pueblo County. By the end of the season the animals infected include 380 horses, of which 93 died; 138 birds; and 14 humans. All Coloradoans who had the West Nile virus have recovered or are recovering.

Douglas H. Benevento, the executive director of the Department of Public Health and Environment, urged Coloradans to take precautions against being bitten by the mosquitoes and to reduce mosquito breeding grounds near their homes.However he added, "The chances that any one person is going to become ill from a mosquito bite is extremely low. Although most people do not become ill, for those who do, the time between the mosquito bite and the onset of symptoms ranges from five to 15 days. Most individuals suffer from a fever, headaches and lethargy for two to seven days before they recover."

Those who do become more seriously ill with encephalitis as a result of being infected with West Nile virus tend to be 50 years of age and older, health officials said.

West Nile virus has been moving across the United States from east to west since first striking New York City in the summer of 1999.