Mild Viral Rashes in Children
Immunizations Aren’t Indicated for Many Childhood Diseases
Oct 2, 2009
Vaccines are intended to prevent the spread of contagious illnesses that cause significant morbidity or mortality in any segment of a population that might be exposed to the disease.
Due to widespread immunization programs, complications from measles, chickenpox, and rubella are much less common now than in years past, and smallpox has been eradicated.
However, any number of viruses can cause rashes, and any rash on a child evokes anxiety in concerned parents, often prompting a call to a doctor.
Dealing with a Child's Rash
Usually, a previously immunized child who develops a rash but is otherwise acting normally can simply be observed – even if a low-grade fever (up to 101.5ºF) is present. Of course, any child whose condition deteriorates should be immediately evaluated.
Conversely, unimmunized children serve as a potential reservoir for communicable viral illnesses within a community. Even though a non-immune child appears otherwise normal, the appearance of a rash may signal the onset of a disease that is dangerous to the child or to those around the child.
For example, rubella – a disease that is typically mild for most children – can cause serious birth defects, spontaneous abortions, or stillbirths in any unimmunized pregnant woman who comes in contact with the infected child.
Thus, an unimmunized child who develops a rash should probably be seen by a health care provider. A phone call prior to taking the youngster to a clinic will help to ensure that other patients in the waiting room will not be exposed.
Some Viruses that Cause Rashes Are Relatively Benign
Many of the myriad viruses that cause rashes haven’t even been characterized. Thus, a pediatrician examining a child’s rash may simply pronounce it a “viral exanthem” without attempting to identify it.
The usual advice about fever control, fluids, and observation will be dispensed, and the child (along with a still-worried parent) will be sent on his or her way.
Occasionally, though, a physician is confronted by a familiar-looking rash, and everyone concerned is reassured when it can be given a name:
Human Parvovirus B19
- Also known as “fifth disease” or erythema infectiosum, human parvovirus B19 often causes mild springtime outbreaks in 5- to 7-year-old children. It is spread by respiratory droplets and is easily transmitted to household contacts.
- Asymptomatic infection can occur, allowing the virus to spread silently (i.e., without known sick contacts).
- The incubation period lasts from 4 to 14 days, after which mild flu-like symptoms appear. Fever is typically low, and activity levels are usually unaffected.
- Several days after the onset of initial symptoms, a classic, reddened, confluent rash appears over the cheeks, giving the child a “slapped-cheek” appearance. The rash – which is most prominent on exposed skin – then spreads to the trunk and extremities, usually sparing the palms and soles.
- As it spreads, the rash develops a lacy or net-like appearance. Although the rash may wax and wane for several weeks, the illness usually resolves within 5 – 10 days.
- Because human parvovirus B19 has been associated with fetal death in women who acquire the infection during pregnancy, and because the virus occasionally causes serious suppression of red blood cell production, a vaccine may one day become available.
Roseola Infantum
- Often called “pseudorubella” because of its resemblance to that disease, roseola infantum is caused by a virus from the herpes virus family. It, too, causes localized springtime outbreaks, mostly in infants and very young children.
- A 5- to 15-day incubation period is followed by an abrupt fever (sometimes over 104º F) without any other clinical signs of infection. The child often continues to act normally despite the fever. The lymph nodes behind the ears and on the neck may swell.
- On the 4th or 5th day the fever falls rapidly, and the child may develop a reddened, patchy or pimply rash that is most prominent on the chest and abdomen. 70% of infected children never develop a rash, so many of these patients undergo extensive medical workups to determine the cause of the fever.
- If the rash does develop, it usually lasts a few hours to 2 days, and then the illness resolves.
Other Rash-Provoking Viruses
- Coxsackie A4 – 6, A9, B1, 3, 4, 5, 16
- Echovirus 2, 4, 9, 11, 14, 16, 19, 25
- Molluscum contagiosum virus
- Alphavirus (some)
- Rashes can erupt on the head, face, neck, trunk, extremities, or mucus membranes and can be patchy, pimply, pinpoint, blistered, hemorrhagic (i.e., raised, blood-filled blisters), or petechial (flat “blood blisters”).
- Other symptoms may or may not occur.
As more viruses are characterized – along with their associated rashes and complications – new vaccines will probably be added to the array of immunizations that are already presented to children. Hopefully, improvements in vaccine administration and safety will parallel advancements in epidemiology.
(Adapted from Infectious Diseases and Infections in Infants and Children in The Merck Manual, 18th Edition. 2006)
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