A Look at Parvovirus in Humans

Human parvovirus is a single-stranded DNA virus that was discovered in the 1970s by Australian virologist Yvonne Cossart and was called B19 because it was found in serum samples labelled B19.

The human parvovirus is a highly infectious organism that is spread by respiratory droplets or sometimes by blood-borne transmission or from a mother to her unborn child. It can trigger a sharp decline in the production of red blood cells and causes a mid rash in children in several parts of the body. On the face the rash looks like someone has slapped the child which is why fifth disease is sometimes known as "slapped cheek syndrome". By the time the rash appears the virus is no longer infectious.

B19 outbreaks tend to occur in late winter/early spring and they affect males and females equally.

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• Mild fever
• Nausea
• Headache
• Red facial rash
• Mild itchy rashes on arms, legs and trunk
• Scaly dermatitis - an inflammation of the skin

In adults infected by the human parvovirus the symptoms can be more severe and include: -

• Pain in the bones and joints
• Inflammation of the joints

There is no long term damage to otherwise healthy adults and children who have been infected with B19.

Some people infected with the human parvovirus will not show any symptoms of disease. According to the Centers for Disease Control about 20% of children and adults with the virus will be symptomless.

Human parvovirus behaves like many other virus molecules. It attaches to host cells before sending its contents shooting into the nucleus where it hijacks the genetic machinery to produce new virus particles. The host cell is destroyed as the newly minted virus particles leave it to infect other cells, tissues, and organs in the body.

This particular virus targets erythroid progenitor cells, which are found in bone marrow, fetal liver, the umbilical cord, and peripheral blood.

The B19 virus has also been implicated in other diseases. For example, it can cause chronic anaemia in people who have AIDS and it can lead to arthritis in adults, and also in some children. People who have sickle cell anaemia and become infected with B19 may suffer an aplastic crisis. This is a drastic cessation of the production of red blood cells, and it can be treated with a blood transfusion.

Fifth disease is known as a self-limiting illness which means that it usually resolves itself without complications, though blood transfusions may need to be given to those with severe or chronic cessation of red blood cell production. For most people home treatments such as plenty of rest, pain relief and fluids are sufficient.