The West Nile Virus is randomly popping up all over the Brazos Valley.
And according to the Centers for Disease Control, 80 percent of humans that contract the virus never show any symptoms.
But just because there are no symptoms doesn't mean the virus can't be passed on to others. And now blood centers are on the look-out.
"We became more aware of West Nile and that it was transferred and carried in the blood. So anything that's blood related we get actively involved and begin testing," said Theresa Evangelista with the American Red Cross.
West Nile has infected people through blood transfusions in the past, even though the donor showed no symptoms.
Now the FDA requires that all blood centers screen for West Nile year round, not just in the summer when the virus is most common.
"Every unit that is drawn is also tested for the West Nile virus, if the test comes up positive that unit is destroyed and the donor is contacted," said Evangelista.
West Nile contaminated blood is not very common in the Brazos Valley, but the local Red Cross has had at least two reported cases.
"We did some research on it and in the State of Texas they've actually come up with 16 cases, but only two in our area," said Evangelista.
The National Center for Infectious Diseases estimates that screening for West Nile has prevented about 1,500 infections since 2003.
And although the number of infections that occurred via transfusions is unknown, experts believe there have been several hundred.