Fifth Disease (Parvovirus, Erythema Infectiosum)

• A virus causesfifth disease.
• Symptoms include lowfever,fatigue, a "slapped cheeks"rash,joint pains, and a whole bodyrash.
• Doctors make a diagnosis of fifth disease based on clinical features.
• Rarely, fifth disease can become complicated.
• Fifth disease can causemiscarriageinpregnantwomen.

Fifth disease is a viral illness caused by human parvovirus B19.Erythema infectiosumandslapped cheek syndromeare other names for fifth disease. Health care professionals first described fifth disease in 1896 and named the illness fifth disease because of its fifth position in the numerical classification of sixchildhood illnesses与rashes(exanthems). Other numbered viral exanthems includedmeasles(rubeolaor first disease),rubella(Germanmeaslesor third disease), and红疹infantum (sixth disease). The bacteriumStreptococcuspyogenescausesscarlet fever, or "second disease." Doctors no longer classify fourth disease as a clinical entity. Health care providers did not rename these illnesses until the molecular era, when it became possible to isolatevirusesand bacteria. Parvovirus infection is very common. Almost 50% of adults have had a parvovirus B19 infection but often do not remember having it because this infection frequently does not cause symptoms.

Fifth disease generally occurs in school-age children between 4-10 years of age, but it can affect any age group. Parvovirus infection most commonly occurs during the winter and spring. The illness classically begins with a low-gradefever,headache,runny nose,sore throat, and malaise (a sense of not feeling well). Of course, thesecold-like symptomsmimic any other viral illness, so it is impossible to determine the cause early in the illness. After about a week, a characteristic bright red rash on the cheeks (the so-called "slapped cheeks") follows the initial symptoms. Finally, after three to four days, a fine, red, lace-like rash can develop over the rest of the body. This rash may last for five to seven days and occasionally comes and goes for several weeks. The other symptoms are usually gone by the time the rash appears. Patients with the rash are usually notcontagious. Unfortunately, as with many other viral illnesses, the features and timing of the different stages of illness are often unpredictable.

Unlike other viral infections that usually causehand, foot, and mouth disease(namely coxsackievirus A16 andenterovirus71), fifth disease does not typically involve the palms and soles. However, some adults infected with parvovirus B19 can develop redness and swelling of hands andfeet.

Around 5% of children and about half of adults with fifth disease experience joint pains. Thisarthritisor arthropathy is more common in females than males, is usually temporary, lasting for a few days to weeks, and may become a long-term problem for months. People witharthritisfrom fifth disease usually havestiffnessin the morning, with redness and swelling of the same joints on both sides of the body ("symmetrical" arthritis). The joints most commonly involved are the knees, fingers, and wrists.

Rarely, these patients develop erythrocyte aplasia, meaning the bone marrow stops forming a normal number of红细胞(anemia). This complication is rare and usually transient, butanemiacan be life-threatening. Patients who have compromised immune systems (by disease or treatment) are at high risk of this complication.

Pregnant women (who have not previously had the illness) should avoid contact with patients who have fifth disease. The fifth disease virus can infect the fetus prior to birth. Although no birth defects have been reported because of fifth disease, for 2%-10% of B19-infected pregnant women, fifth disease can cause severe anemia and even the death of the unborn fetus (by hydrops fetalis). Blood tests for parvovirus B19 are not routinely included in preconception or antenatal screenings.

The only available treatment is supportive. Fluids,acetaminophen(Tylenol), and rest provide relief. Antibiotics are useless against fifth disease, because it is a viral illness. People with persistent arthritis can use anti-inflammatory medications such asibuprofen(Advil) ornaproxen(Aleve), though children should not takeaspirindue to the risk of developing Reye syndrome.

细小病毒B19通常通过飞沫传播。virus spreads whenever an infected personcoughsor sneezes. However, once the rash is present, that person is usually no longer contagious and need not be isolated.

Similar to most viral illnesses, the best way to prevent the spread of the disease is by proper hand washing, by covering your mouth and nose when you sneeze orcough, and by staying home when you become sick.