APPLETON, Wis. (WFRV) - Wisconsin health officials confirmed two elderly women died, after they had probable cases of the West Nile virus.

The victims were a 78-year-old Greenfield woman from Milwaukee County, and a 71-year-old woman from Waukesha County.

More tests are needed before federal officials can confirm that West Nile caused the deaths.

If that's the case, they would be Wisconsin's first deaths from the mosquito-borne West Nile virus since 2008.

As of Wednesday, the state had one confirmed case and 12 probable cases - the most since 2007.

Because not everyone shows symptoms some cases have been caught at blood donation centers.

"We go to all ends to make sure that the blood supply is safe" says Rick Hart, President / CEO of the Community Blood Center.

While tainted blood has not shown up anywhere in Northeast Wisconsin, The Community Blood Center is prepared if a test comes back positive.

"We immediately intercede and pull the product, quarantine it and ultimately do additional  testing so we know what we are dealing with" explains Hart.

Blood is tested in several different ways, using state of the art equipment. The process takes 6 hours for each tube of blood.

According to Hart "We test every donor, every donation, every unit for West Nile Virus to make sure that is not happening".

Even before rolling up their sleeve donors get a mini physical and questionnaire to make sure they are in good health.

It is important to note you cannot contract the virus by donating blood.

There are some symptoms to watch for according to Katie Franklin, MD who practices Family Medicine for Prevea Health.

"A low grade fever, body aches, an overall feeling of fatigue, sometimes headaches".

Doctors say bug spray and keeping skin covered is your best defense. 

Find more tips for preventing West Nile Virus here.