Hi Thanks for posting your query on HCM. Incomplete data may be some typing error. It is apparent that your boyfriend is having a contagious viral infection caused by Parvovirus which is also referred to as slapped-cheek disease because of the rash that develops on the face. In most patients, the infection is mild and requires little treatment. It can cause serious complications in patients with anemia or with weak immune system like it may stop the production of red blood cells and cause an anemia crisis. Patients with sickle cell anemia are at particular risk. For a noncomplicated parvovirus infection, self-care treatment at home is generally sufficient. People with severe anemia may need to be hospitalized and receive blood transfusions. Those with weakened immune systems may receive antibodies, via immune globulin injections, to treat the infection Since it is a highly contagious disease, the transmission can be prevented by washing hands frequently, and not sharing food or drinks. Hope this answers your query.