The federal Occupational Safety and Health Administration has released a bulletin providing information on workplace precautions against West Nile virus, an illness transmitted primarily by mosquitoes. This year, hundreds of cases of the virus have been reported in 33 states. And while the virus had so far bypassed California, as we went to press a Riverside County man became the first person in the state to contract the virus without having recently traveled to affected areas of the country. According to OSHA, employees who work outside are most at risk, especially in warmer weather. Preventive measures you can take include inspecting work areas and eradicating sources of standing water where mosquitoes may breed. And when mosquitoes are present, workers can prevent bites by wearing lightweight loose clothing and applying insect repellent.