Fifth’s Disease, also known as erythema infectiosum, is a common viral illness that frequently affects children. While symptoms might sometimes resemble a previous episode, true reinfection with Fifth’s Disease is generally not expected. This article clarifies the concept of immunity following infection.
What is Fifth’s Disease
Fifth’s Disease is a mild, contagious illness caused by the human parvovirus B19. It is recognized by its distinctive rash, which begins with a bright red appearance on the cheeks, earning it the nickname “slapped cheek disease.” A few days later, a lacy, reticulated rash can develop on the arms, legs, and trunk, sometimes lasting for several weeks. The virus spreads primarily through respiratory droplets when an infected person coughs or sneezes.
Initial symptoms, which may appear before the rash, include a low-grade fever, headache, and cold-like symptoms like a runny nose or sore throat. These early symptoms are mild and can be easily mistaken for other common illnesses. The infection is most contagious during this initial phase, even before the characteristic rash becomes visible.
Immunity to Fifth’s Disease
After a person has been infected with parvovirus B19 and recovered, they develop lasting immunity to Fifth’s Disease. The body’s immune system produces specific antibodies, which provide protection against future infections from the same virus. These antibodies remain detectable in the blood for the rest of a person’s life, indicating a past infection and ongoing immunity.
True reinfection with parvovirus B19 is exceptionally rare for individuals with a healthy immune system. Once protective antibodies are established, the body is equipped to neutralize the virus if re-exposed. Approximately 50% of children and 70% to 85% of adults have evidence of prior parvovirus B19 infection, indicating widespread natural immunity within the population.
Why Symptoms Might Reappear
If someone experiences symptoms similar to Fifth’s Disease again, it is not a result of true reinfection with parvovirus B19. One possibility is that the initial illness was another viral infection with similar, non-specific symptoms. Many viruses can cause rashes and flu-like symptoms that might be confused with parvovirus B19 infection.
A common reason for apparent recurrence is the re-manifestation of the rash. The lacy rash associated with Fifth’s Disease may reappear weeks or even months after the initial infection, even though the person is immune to new infection. This can be triggered by factors such as heat, sun exposure, exercise, fever, or emotional stress. This phenomenon is a reactivation of the rash from the original infection, not a new viral infection.
In rare cases, individuals with weakened immune systems may not clear the parvovirus B19 infection, leading to persistent or recurrent symptoms. This can result in chronic anemia or other complications because their body struggles to produce enough antibodies to control the virus. However, this occurs in specific circumstances and is not typical for healthy individuals.
Important Considerations and Management
For most healthy individuals, Fifth’s Disease is a mild illness that resolves without specific medical intervention. Management focuses on easing symptoms, which may include rest, adequate fluid intake, and over-the-counter medications like acetaminophen or ibuprofen for fever or joint pain. It is important not to give aspirin to children due to the risk of Reye syndrome.
Certain populations need to be aware of Fifth’s Disease due to potential complications, even if they develop immunity after one infection. Pregnant women face a risk of fetal complications if infected during pregnancy, especially in the first half. This can lead to severe anemia in the fetus or, in some cases, hydrops fetalis, a condition involving fluid buildup. Individuals with chronic anemia, such as sickle cell disease, are also susceptible to transient aplastic crisis, a temporary but severe drop in red blood cell production, if they contract parvovirus B19. Immunocompromised individuals, including those with HIV or cancer, may experience more severe or persistent infections. These groups should seek medical advice promptly if exposed to or suspect they have Fifth’s Disease.