Parvovirus B19 is a common virus. Nearly 50% of all adults have been infected sometime during childhood or adolescence. Parvovirus B19 infects only humans. There are also animal parvoviruses, but they do not infect humans. Therefore, a person cannot catch parvovirus B19 from a dog or cat.

The most common illness caused by parvovirus B19 infection is "fifth disease," a mild rash illness that occurs most often in children. The ill child typically has a "slapped-cheek" type of rash on the face and  “lacy” red rashes on the trunk and limbs. Sometimes, the rash can itch. The child is usually not very ill, and the rash goes away in about a week. Once a child recovers from parvovirus infection, there is lasting immunity, which means that the child is protected.

An adult who has not previously been had parvovirus B19 can become ill, and develop a rash, or joint pain or swelling, or all of these symptoms. The joint symptoms usually go away in a week or two, however they can last several months. It resolves without medical treatment among children and adults who are otherwise healthy.

Typically, there is no serious complication for a pregnant woman or her baby because of exposure to fifth disease. About half of all women are already immune to parvovirus B19.  These women and their babies are protected from infection and illness. Even if a woman gets infected with parvovirus B19, she usually feels mild symptoms. Her unborn baby usually does not have any problems associated with the parvovirus B19 infection.

Occasionally, the parvovirus B19 infection will cause severe anemia in the unborn baby and the woman may have a miscarriage. This occurs in less than 5% of all pregnant women who are infected with parvovirus B19 and occurs more commonly during the first half of pregnancy.

If you have been in contact with someone who has fifth disease, or if you have an illness that might be caused by parvovirus B19, you may wish to discuss your situation with your obstetrician or midwife. They may perform a blood test to see if you have become infected with parvovirus B19. The blood test for parvovirus B19 may show that you are immune to parvovirus B19 and have no sign of recent infection; that you are not immune and have not yet been infected; or that you have had a recent infection. If you are immune, then you have nothing further to be concerned about. If you are not immune and not yet infected, then you may wish to avoid further exposure during your pregnancy. If you have had a recent infection, you should discuss with your obstetrician or midwife what to do next.

There is no vaccine that protects against parvovirus B19 infection. Frequent hand washing (with warm water and soap) is recommended asan effective method to reduce the spread of parvovirus.