Fifth Disease (Parvovirus B19)
Parvovirus B19 can happen all year round, but the late winter and springtime are the peak times for the infection. It's better known as "fifth disease," with its characteristic "slapped cheek" appearance, and causes a rash, cold symptoms, fatigue and sometimes joint pains.
It's passed from one person to another though respiratory secretions. If someone in your family has it, there is a 15-30% in-household transmission rate. If someone in your child's school or day care has it, there is a 10-60% transmission rate.
The rash is the most recognizable symptom of the infection. It starts as red facial flushing - the "slapped cheek" appearance. It then moves to the trunk, arms, and legs as a red lacy rash, without affecting the palms of the hands or the soles of the feet. The original rash can last from 3-5 days. This rash can come and go for weeks, especially when the skin is exposed to sunlight or the child participates in vigorous exercise.
This virus can also cause joint pain, in girls more than boys, and in adults more than kids. The joints affected the greatest percentage of the time are the hands, wrists, knees and ankles. These pains should be gone in 1-2 weeks. If they're not, we need to think of other disease processes besides this virus.
There isn't anything in the way of labs that we do for this virus. In fact, by the time the rash shows up the kids aren't likely to be infectious anymore. Isolation at, and exclusion from day care are completely unnecessary.
This infection is dangerous in children with underlying immune deficiency or other immune system problems from things like chemotherapy. Other children with sickle cell disease, thalassemia, herditary spherocytosis, pyruvate kinase deficiency and other causes of chronic red blood cell destruction are susceptible to bone marrow suppression from this virus.
I get a bunch of questions about pregnancy parvovirus B19. It's true that this virus can be extremely harmful in all stages of pregnancy because it crosses the placenta. It can cause miscarriage in each trimester. However, most infections in pregnancy result in normal deliveries at term. The incidence of bad outcome with maternal infection is less than 5% of all infections. At this point, there is no recommendation to exclude women from places where children infected with parvovirus are also at because it is unlikely to reduce the risk of infection. It's the pregnant mom who have never had the disease who is the most at risk. There is no vaccine available.