Polycythemia vera (PV) is a blood disease in which the bone marrow makes too many red blood cells, causing a thickening of the blood.

PV usually takes years to develop. Most people are diagnosed with PV later in life, most often around age 60 or older. People with PV might experience headaches, tiredness and shortness of breath. They are also at risk for getting blood clots, which can lead to heart attacks and stroke.

At this time, there is no cure for PV. But treatment can control symptoms and avoid heart problems. Some people with PV do not need treatment but should see their doctor regularly to stay as healthy as possible and to catch problems early, according to information provided by the federal Agency for Toxic Substances and Disease Registry (ATSDR).

In 2008, the Pa. Department of Health and the ATSDR confirmed more PV cases than expected in parts of Schuylkill, Carbon and Luzerne counties.

The Department of Health and ATSDR are tracking patterns of PV and working with research partners in looking for trends and risk factors. In addition, the Center for Disease Control is working to improve reporting systems for PV.