What is the organism (if any) of fifth disease (erythemia infectiosum)?

Especially common in children between the ages of 5 and 15, fifth disease typically produces a distinctive red rash on the face that makes the child appear to have a slapped cheek. The rash then spreads to the trunk, arms, and legs. Despite being called a "disease," fifth disease is actually just a viral illness that most children recover from quickly and without complications.

Fifth disease (also called erythema infectiosum) is caused by parvovirus B19. A human virus, parvovirus B19 is not the same parvovirus that veterinarians may be concerned about in pets, especially dogs, and it cannot be passed from humans to animals or vice versa.

Studies show that although 40% to 60% of adults worldwide have laboratory evidence of a past parvovirus B19 infection, most of these adults can't remember having had symptoms of fifth disease. This leads medical experts to believe that most people with a B19 infection have either very mild symptoms or no symptoms at all.

Fifth disease occurs everywhere in the world. Outbreaks of parvovirus tend to happen in the late winter and early spring, but there may also be sporadic cases of the disease any time throughout the year.

Signs and Symptoms

Fifth disease begins with a low-grade fever, headache, and mild cold-like symptoms (a stuffy or runny nose). These symptoms pass, and the illness seems to be gone until a rash appears a few days later. The bright red rash typically begins on the face. Several days later, the rash spreads and red blotches (usually lighter in color) extend down to the trunk, arms, and legs. The rash usually spares the palms of the hands and soles of the feet. As the centers of the blotches begin to clear, the rash takes on a lacy net-like appearance. Children younger than 10 years of age are most likely to get the rash.

Older children and adults sometimes complain that the rash itches, but most children with a rash caused by fifth disease do not look sick and no longer have fever. It may take 1 to 3 weeks for the rash to completely clear, and during that time it may seem to worsen until it finally fades away entirely.

Certain stimuli (including sunlight, heat, exercise, and stress) may reactivate the rash until it completely fades. Other symptoms that sometimes occur with fifth disease include swollen glands, red eyes, sore throat, diarrhea, and unusual rashes that look like blisters or bruises.

In some cases, especially in adults and older teens, an attack of fifth disease may be followed by joint swelling or pain, often in the hands, wrists, knees, or ankles.

Contagiousness
A person with parvovirus infection is most contagious before the rash appears - either during the incubation period (the time between infection and the onset of symptoms) or during the time when he or she has only mild respiratory symptoms. Because the rash of fifth disease is an immune reaction (a defense response launched by the body against foreign substances like germs) that occurs after the infection has passed, a child is usually not contagious once the rash appears.

Parvovirus B19 spreads easily from person to person in fluids from the nose, mouth, and throat of someone with the infection, especially through large droplets from coughs and sneezes. It can also be spread through shared drinking glasses and utensils.

In households where a child has fifth disease, another family member who hasn't previously had parvovirus B19 has about a 50% chance of also getting the infection. Classmates of children with fifth disease have about a 60% chance of getting the virus. Once someone is infected with parvovirus B19, they develop immunity to it and won't usually become infected again.

http://www.kidshealth.org/parent/infecti...

Parvovirus B19.

See the link below for more info:
http://www.emedicine.com/derm/topic136.h...

Darn, someone else answered before I got to say "human parvo"...but they got it right!