"If they are bitten by a mosquito that is infected with any one of the viruses, Encephalitis virus, or what we call arbo viruses, the chicken will produce antibodies to that virus and we can detect those antibodies in the test," says environmental specialist Marce'e Toliver.
The chickens are kept all across the state to act as an early warning devise.
"We put our Sentinel flocks where humans are at risk. We are not trying to detect things that are not going to affect humans. If it is in the middle of the Great Swamp, there can be a lot of Eastern Equine (disease) out there (which doesn't concern us), because there are not any humans. Our concern is protecting human health," says Tolliver.
The chickens can reveal the presence of Equine infectious Encephalitis, which infects both horses and humans, St. Louis Encephalitis, and although not the primary target, they can also reveal the West Nile virus.
"The chicken is not harmed, the chicken is not hurt by getting the virus, it will naturally fight off that virus so all we do is go back in and using the blood sample, we look for antibodies to those virus and then we find out that yes, the virus is present in that community," says Tolliver.
So does Tolliver get bitten, too?
"Yes, so what we recommend to the public is wear long sleeves, wear long pants, and wear repellents if you are going to be out for long," she says.
One of the perks of maintaining the Sentinel flock is the care-taker gets to keep all of the eggs. So far, the flock has not detected the West Nile Virus in North Carolina.