Fifth disease spreads easily from person to person through the fluids in the mouth, nose, and throat of an infected person. It occurs everywhere in the world, usually in late winter or early spring. Most people have no symptoms, but those who do often mistake them for a mild cold or flu, with a low-grade fever and a runny and stuffy nose. Fifth disease begins so much like a mild cold, in fact, that there is no way to clearly identify it during the early stages when it is contagious, and the only prevention is good hygiene, such as constant hand washing and avoiding the sharing of glasses and utensils. There is no vaccine against parvovirus B19, and no treatment apart from the alleviation of symptoms.
Fifth disease is sometimes called slapped cheek syndrome because of its telltale red rash, which usually occurs in children ten and under. The rash begins on the face and spreads across the cheeks in a way that gives the child the appearance of having been slapped. Although it can be alarming for parents, by the time the rash appears the previous symptoms have subsided and the child usually feels much better. The virus is no longer contagious at this point, and the rash gives no other discomfort apart from a mild itch that does not occur in all cases.
The rash generally spreads over the next few days in a lacelike pattern from the face down the trunk, arms, legs, and buttocks. It can last three weeks or even longer in some cases, and can reappear long after it has gone with exposure to heat, sun, exercise, or stress. Fifth disease is usually diagnosed by an examination of the rash, but in its absence a blood test can be performed on a child who is ill to confirm or rule out the virus.
Other symptoms can occur, such as swollen glands, red eyes, a sore throat, diarrhea, and joint swelling or pain. The joint pain is usually experienced by older children or teenagers, and occurs in the hands, wrists, knees or ankles, lasting anywhere from a few days, to a few weeks, to several years.
Though considered a mild illness, serious complications can occur if the virus is contracted by children with cancer, HIV, or sickle-cell anemia. Fifth disease temporarily slows down or stops the production of red blood cells. In a healthy child this poses little risk, but in a child with a compromised immune system it can cause severe anemia that may lead to the need for a blood transfusion.
Similarly, fetal anemia can occur if a pregnant woman contracts fifth disease and transmits it to her fetus. This can be severe enough lead to death of the fetus or require an intra-uterine fetal blood transfusion. Pregnant women who have been recently exposed to the virus should be tested to see if they have immunity due to a previous infection. If they do not, they should be periodically tested to ensure they have not contracted the illness.