Parvovirus B19 is a common childhood illness also known as Fifth’s Disease. Its other names are “slapped cheek” illness and erythema infectiosum. It is characterized by a pink splotchy rash usually starts on the face and looks like a slapped cheek. The rash can then spread to the trunk and limbs as a pinkish spots and splotches. The splotches can take on a lacy appearance as the center area clears. The rash can wax and wane over a week or two, Heat, exercise and excitement can make the rash more intense. In many cases the rash is very faint. The reason the illness was called Fifth disease is that it was grouped with the other childhood illnesses: Measles, Mumps, Rubella and Scarlet fever.
When a child develops the rash of Fifth’s disease he/she is actually recovered from the illness and is no longer contagious. He/she may go to school.
The child had been contagious about 7-10 days before the rash appears. During the actual illness, when the virus is circulating in the blood stream, symptoms can be very mild; upper respiratory congestion, and perhaps a low grade fever or headache. In most children the symptoms are so mild that when the rash appears a week or two later, the parents hadn’t realized the child had been sick and wonder what the rash is.
The virus is spread through respiratory droplet and the incubation period is about a week or week and a half between contact with the virus, and development of the symptoms when the child is ‘viremic’. The slapped cheek rash then appears about a week and a half after the illness, hence the illness is usually diagnosed about two and a half weeks after the child was exposed to it.
Complicated Forms of Parvovirus
For the vast majority of people, Parvorus is a mild, self-limited illness. However, it can cause serious disease in people with certain conditions such as Sickle Cell disease, Thallesemia, and those with depressed immune systems. This is because the virus actually ‘home to’ and repllicate in the red blood cell precursor of the person’s bone marrow . During the ‘viremic’ phase, those developing blood cells that are effected by the virus as destroyed by the immune system. In a healthy person, this loss of “a few thousand” red blood cell percursors are neglible and cause no symptoms. However, if a person has a condition where their red blood cells have a higher turnover – such as sickle cell disease and thallesema, parvovirus can cause an “Aplastic crisis”, in which there is such a severe anemia, that blood transfusion is required. Children with sickle cell also can experience a pain crisis due to sickling of red cells in their blood vessels.
Another possible complication of parvovirus is a transient arthritis or arthropathy (achy joints). This happens more commonly in adults and teenagers. There can be an achiness of the joints in the hands, wrists, knees and ankles due to antibodies floating through the body. The achy joint symptoms resolve spontaneously in 2 – 4 weeks. Warm baths can help minimize the achiness.
Parvovirus and pregnancy
Parvovirus can affect the fetus if the mother experiences a primary infection. Fortunately, more than half of women have had parvovirus B19 before reaching childbearing age. Also, in the majority of cases mothers who have parvovirus during pregnancy will go on to deliver a healthy, normal baby. If a pregnant woman experiences a primary parvovirus B19 infection the developing red blood cells of the fetus can be affected, leading to profound anemia and heart failure. The most susceptible period is the second trimester and there is an estimated 5% risk that the fetus will not survive. Fortunately, in most cases, the fetus will be able to withstand the virus and the mother will deliver a healthy, normal baby.
Because parvovirus is contagious through respiratory droplet about 2-3 weeks prior to any diagnosis, pregnant women should avoid kissing and hugging children who are not their own. Most parvovirus illness occurs in 5-15 year olds.