1, 2, 3, 4, Fifth Disease!
If you have ever seen the rash called fifth disease (or erythema infectiosum), then you have probably never forgotten it. Fifth disease is also called “slapped-cheek syndrome” because children with this virus have a very characteristic red rash on their cheeks.
I used to think that fifth was caused by a herpes virus, but I was wrong! In fact, fifth is caused by parvovirus B19. Parvoviruses are some of the smallest viruses and they are very resilient. They can survive up to a year in the environment. There are different parvoviruses that can infect many mammalian species, however it is not usual for parvoviruses to be passed from animals to humans.
Symptoms. Fifth disease is common in kids aged 5-15 years old. Similar to a lot of viral infections, fifth disease often starts with a mild headache, low-grade fever and stuffy or runny nose. You know it is fifth disease and not some other random viral illness when the characteristic rash appears on the face a few days later. Although the rash starts in the face, it often extends down the trunk, arms and legs within a couple of days. The rash on the extremities is very lacy. Unlike hand, foot and mouth disease, the rash caused by fifth disease usually does not appear on the palms or soles of the feet.
Fifth disease is often very mild in kids. Although you may be perturbed by the rash, by the time it appears, your kids are usually up and running again. One curious thing about the rash – it can disappear and reappear again when your child becomes heated – like after a bath or being out in the sun. It can be very frustrating when you are trying to convince your spouse that your child has a rash and it disappears before you can show him/her!
Parvovirus B19 is pretty contagious. It is spread through fluids, particularly in coughs and sneezes. It can be hard to control because it is most contagious before any symptoms appear. In fact, kids are usually not considered contagious once the rash appears. Unlike herpes viruses, once you are infected with parvovirus B19 you develop immunity and won’t have any trouble with the virus again.
When parvovirus is more dangerous. Although parvovirus B19 is usually benign, it is more troublesome in certain populations. The virus can slow down or halt the production of red blood cells causing a temporary anemia. In healthy children this goes unnoticed, but in children with weakened immune systems or those already suffering from other types of anemia, it can be life-threatening.
Parvovirus B19 also causes fetal distress and miscarriage due to severe anemia. This is unusual however and occurs in less than 5% of pregnant women who become infected and are not immune to the virus (30-50% of people are immune to the virus due to previous infection).
More commonly (although still rare) parvovirus can cause an arthritis when people are infected as adults (and sometimes older children). Joint pain usually lasts 1-3 weeks, but in some instances can last several months. Arthritis caused by parvovirus B19 is temporary and does not progress to other forms of arthritis.
Why is it called fifth? The rash associated with parvovirus B19 was named fifth disease because it was originally classified as one of the 6 common childhood rashes. These rashes are:
- First disease: measles
- Second disease: scarlet fever
- Third disease: Rubella (German measles)
- Fourth disease: Duke’s disease (not considered a separate illness any longer)
- Fifth disease: erythema infectiosum
- Sixth disease: roseola
Thanks to vaccines and modern medicine, only 2 of these are still common!