Human parvovirus B19 infections, also known as fifth disease, is an infection by a specific virus that only affects humans. Parvovirus is highly contagious in children and causes a rash on the face which due to its appearance is called a "slap rash". Usually infections in children do not last very long and the associated rash can be treated at home with over the counter anti-rash remedies. Adults may also get parvovirus but their symptoms are usually limited to joint pain and immobility. People with weakened immune systems caused by leukemia, cancer, organ transplants, or HIV infection are at risk for serious complications from fifth disease. It can cause chronic anemia that requires medical treatment.