Fifth disease, also called erythema infectiosum, is a viral infection caused by human parvovirus B19. It occurs most commonly in children with up to 70% of all cases occurring in children 5 to 15 years old.
Called fifth disease because it was historically the fifth childhood infectious rash to be named, this viral infection occurs worldwide but is more common in temperate climates. Epidemics are seasonal with most outbreaks occurring in the winter and spring. The infection seems to be more common in girls than boys.
There is no vaccine for fifth disease. However, once you're infected with the virus, you're immune for life against future infections.
Fifth disease is caused by human parvovirus B19, a virus that only affects humans. It is transmitted from person to person the same way as any viral cold is spread. The infection is most commonly spread by inhaling air containing viral particles after an infected person has coughed or sneezed, or by sharing drinking vessels or eating utensils. It can also be passed from an infected pregnant woman to an unborn child and through blood transfusions.
Coming in contact with the virus doesn't necessarily mean that you'll get infected. About 50% of people living with someone infected with fifth disease will get the infection and 10% to 60% of students will get infected during school or daycare outbreaks.
Symptoms and Complications
The symptoms of fifth disease are usually mild, and up to 25% of adults and children infected with the virus will not develop symptoms at all.
If symptoms do develop, they usually start to appear about 4 to 14 days after becoming infected with the virus. The first symptom of fifth disease is usually a mild, red rash on the cheeks that looks like the face has been slapped. This is followed by a red, lacy rash on the arms, legs, stomach, and back. The rash occurs in 75% of children and 50% of adults. The rash will disappear on its own in 7 to 10 days, but may rarely reappear and clear for several weeks.
Other symptoms associated with fifth disease include:
- low-grade fever a few days prior to the rash (more common in adults)
- sore throat
- stomach pain
- joint pain lasting 2 to 3 days (more common in adults)
Infection during pregnancy can cause severe anemia in the unborn child. However, the chance of this occurring is very small. There is also a small chance of miscarriage when infection occurs during pregnancy, especially in the first trimester. If you are pregnant and are exposed to someone with fifth disease, contact your doctor.
Severe complications are rare with fifth disease. However, if you have certain medical conditions (e.g., immune system problems, cancer, leukemia, or have had an organ transplant), you may become more seriously ill with fifth disease. Talk to your doctor if you have any of these medical conditions and think you may have been exposed or infected.
Making the Diagnosis
Fifth disease often goes undiagnosed because some people do not have symptoms. When symptoms do occur, a doctor can usually make the diagnosis based on the symptoms, especially the characteristic rash.
Blood tests may be done to check for antibodies to confirm the diagnosis or to check for immunity in a pregnant woman who has been exposed to the virus.
Treatment and Prevention
Fifth disease is usually a mild illness and goes away without medical treatment in children and adults who are otherwise healthy. There is no specific treatment for fifth disease.
Doctors usually treat symptoms such as fever, pain, and headache with non-prescription medications such as acetaminophen* or ibuprofen. Remember never to give acetylsalicylic acid (ASA) to children with a viral infection, as its use in these circumstances is linked to a dangerous condition called Reye's syndrome. If you or your child develop a rash, try to avoid excessive heat or sunlight as this may cause to rash to worsen or recur.
Fifth disease is only contagious at the beginning of the infection. Once the rash appears, the infection is no longer contagious. Therefore, there is no need to keep infected children home from school or daycare once the rash has appeared.
There is no vaccine to prevent fifth disease. However, good hygiene including proper hand-washing can help prevent the spread of the virus.