The risk of acquiring the viral illness increases when exposed to an infected person or contaminated blood. Individuals who have an occupation that requires close contact with infected people such as healthcare workers and teachers are at an increased risk of acquiring the viral illness. Another risk factor of fifth disease are immunocompromised individuals, those with anemia are at a higher risk of developing complications. Pregnant women are at risk for acquiring viral illness, especially during the first half of pregnancy. Though, complications are very rare and less than 5% of these cases will experience serious complications. The most common complication among pregnant women is anemia. In rare cases, severe anemia can occur, and a buildup of fluid can develop. A buildup of fluid can cause congestive heart failure or death. A blood infusion or induction may be necessary. No vaccine is available for human parvovirus B19, though attempts have been made to develop one. History
Parvovirus, the virus causing the fifth disease, was first discovered in 1975 by Yvonne Cossart. It,  or a disease presenting similarly, was first described by Robert Willan in his book called On Cutaneous Diseases in 1808 as "rubeola, sine catarrho". It was better defined by Anton Tschamer in 1889 as a rubella variant (Ortliche Rotheln) and described it as abortive rubella, identified as a distinct condition in 1896 by Theodor Escherich, and given the name "erythema infectiosum" in 1899.
In addition, individual intervals have been established:

For children, the cutoffs for splenomegaly are given in this table, when measuring the greatest length of the spleen between its dome and its tip, in the coronal plane through its hilum while breathing quietly.At autopsy, splenomegaly can be defined as a spleen weight above the upper limit of the standard reference range of 230 g (8.1 oz).Splenomegaly refers strictly to spleen enlargement, and is distinct from hypersplenism, which connotes overactive function by a spleen of any size. Splenomegaly and hypersplenism should not be confused. Each may be found separately, or they may coexist. Clinically, if a spleen is palpable (felt via external examination), it means it is enlarged as it has to undergo at least twofold enlargement to become palpable. However, the tip of the spleen may be palpable in a newborn baby up to three months of age. Signs and symptoms
Symptoms may include abdominal pain, chest pain, chest pain similar to pleuritic pain when stomach, bladder or bowels are full, back pain, early satiety due to splenic encroachment, or the symptoms of anemia due to accompanying cytopenia. Signs of splenomegaly may include a palpable left upper quadrant abdominal mass or splenic rub. It can be detected on physical examination by using Castells sign, Traubes space percussion or Nixons sign, but an ultrasound can be used to confirm diagnosis.