MILWAUKEE (CBS 58) -- The City of Milwaukee Health Department says two human cases of West Nile virus (WNV) have been reported in Milwaukee. It comes after reports of several other cases in Wisconsin this year. 

The virus is transmitted through the bite of an infected mosquito - it cannot be spread directly between people, animals, or from animals to humans. 

The health department says West Nile virus cases in Wisconsin are most common during August and September, but the risk lasts until a hard frost, defined as temperatures below 28 degrees for at least four consecutive hours. 

Officials say about 80% of people infected with the virus do not develop symptoms, and those who do, may experience mild symptoms like "fever, headache, muscle aches, rash, and fatigue."

The virus can lead to severe illness in rare cases -- older adults and those with weakened immune systems are at greater risk of complications. 

The health department says residents are encouraged to minimize exposure to mosquitoes and eliminate breeding sites. 

Local health departments recommend the following prevention tips:

Avoid Mosquito Bites

• Use insect repellents containing DEET, picaridin, oil of lemon eucalyptus, or IR3535.
• Treat clothing with permethrin before going outdoors; do not apply permethrin directly to the skin.
• Reschedule outdoor activities during peak mosquito activity in the evening and early morning.
• Wear long sleeves, pants, and socks to cover exposed skin.

Mosquito-Proof Your Home

• Remove standing water to prevent mosquito breeding:
• Empty water from containers, flower pots, tires, gutters, and downspouts.
• Turn over items like wheelbarrows, kiddie pools, buckets, and boats when not in use.
• Change water in birdbaths and pet dishes every three days.
• Clean and chlorinate pools, hot tubs, and saunas, and drain pool covers.
• Ensure window and door screens are intact to keep mosquitoes out.
• Trim tall grass, weeds, and vines where mosquitoes rest during the day.