fifth disease

Fifth disease is a mild childhood illness caused by the human parvovirus B19 that causes flu-like symptoms and a rash. It is called fifth disease because it was fifth on a list of common childhood illnesses that are accompanied by a rash, including measles, rubella or German measles, scarlet fever (or scarlatina), and scarlatinella, a variant of scarlet fever.

The Latin name for the disease is erythema infectiosum, meaning infectious redness. It is also called the "slapped cheek disease" because, when the bright red rash first appears on the cheeks, it looks as if the face has been slapped. Anyone can get the disease, but it occurs more frequently in school-aged children. The disease is usually mild, and both children and adults usually recover quickly without complications. In fact, some individuals exhibit no symptoms and never even feel ill. Outbreaks most often occur in the winter and spring.

Fifth disease is caused by the human parvovirus B19, a member of the Parvoviridae family of viruses, that lives in the nose and throat of the infected person. The virus is spread through the air by coughing and sneezing. Because the virus needs a rapidly dividing cell in order to multiply, it attacks the red blood cells of the body. Once infected, a person is believed to be immune to reinfection.

Symptoms may appear four to 21 days after being exposed to the virus. Initial symptoms are flu-like and include headache, body ache, sore throat, a mild fever of 101 °F (38.3 °C), and chills. It is at this time, prior to the development of the rash, that individuals are contagious. These symptoms last for two to three days. In children, a bright red rash that looks like a slap mark develops suddenly on the cheeks. The rash may be flat or raised and may or may not be itchy. Sometimes, the rash spreads to the arms, legs, and trunk, where it has a lace-like or net-like appearance. The rash can also involve the palms of the hands and soles of the feet. By the time the rash appears, individuals are no longer infectious. On average, the rash lasts for 10-11 days, but may last for as long as five to six weeks. The rash may fade away and then reappear upon exposure to sunlight, hot baths, emotional distress, or vigorous exercise.

Adults generally do not develop a rash, but instead may have swollen and painful joints, especially in the hands and feet. In adults, symptoms such as sore throat, headache, muscle and joint pain, abdominal pain, diarrhea, and vomiting occur more frequently than in children and are usually more severe. The joint pain can be arthritis-like and last for several months, especially in women, but the disease does not appear to progress to rheumatoid arthritis.

The virus causes the destruction of red blood cells and, therefore, a deficiency in the oxygen-carrying capacity of the blood (anemia) can result. In healthy people, the anemia is mild and only lasts a short while. In people with weakened immune systems, however, either because they have a chronic disease like AIDS or cancer (immunocompromised), or are receiving medication to suppress the immune system (immunosuppressed), such as organ transplant recipients, this anemia can be severe and last long after the infection has subsided. Symptoms of anemia include fatigue, lack of color, lack of energy, and shortness of breath. Some individuals with sickle cell anemia, iron deficiency, a number of different hereditary blood disorders, and those who have received bone marrow transplantations may be susceptible to developing a potentially life-threatening complication called a transient aplastic crisis where the body is temporarily unable to form new red blood cells.

In very rare instances, the virus can cause inflammation of different areas of the body, including the brain (encephalitis), the covering of the brain and spinal cord (meningitis), the lungs (pneumonitis), the liver (hepatitis), and the heart muscle (myocarditis). The virus can also aggravate symptoms for people with an autoimmune disease called systemic lupus erythematosus.

There is some concern about fifth disease in pregnant women. Although no association with an increased number of birth defects has been demonstrated, there is concern that infection during the first three months of pregnancy may lead to a slight increase in the number of miscarriages. There is also some concern that infection later in pregnancy may involve a very small risk of premature delivery or stillbirths. As a result, women who get fifth disease while they are pregnant should be monitored closely by a physician.

Fifth disease is usually suspected based on a patient's symptoms, including the typical appearance of the bright red rash on the cheeks, patient history, age, and the time of year. The physician will also exclude other potential causes for the symptoms and rash, including rubella, infectious mononucleosis, bacterial infections like Lyme disease, allergic reactions, and lupus.

In addition, there is a blood test for fifth disease, but it is generally used only for pregnant women and for people who have weakened immune systems or who suffer from blood disorders, such as sickle cell anemia. The test involves measuring for a particular antibody or protein that the body produces in response to infection with the human parvovirus B19. The test is 92-97% specific for this disease.

Because fifth disease can pose problems for an unborn fetus exposed to the disease through the mother, testing may also be conducted while a fetus is still in the uterus. This test uses fluid collected from the sac around the fetus (amniotic fluid) instead of blood to detect the viral DNA.

In general, no specific treatment for fifth disease is required. The symptoms can be treated using over-the counter medications, such as acetaminophen (Tylenol) or ibuprofen (Motrin, Advil). If the rash itches, calamine lotion can be applied. Aspirin is usually not given to children under the age of 18 to prevent the development of a serious illness called Reye's syndrome.

Patients who are receiving medications to suppress the immune system in the treatment of some other condition may be allowed to temporarily decrease the medications in order to allow the immune system to combat the infection and recover from the anemia. Those with weakened (not suppressed) immune systems, such as AIDS patients, may be given immunoglobulin intravenously to help the immune system fight the infection. People with severe anemia or who experience an aplastic crisis may require hospitalization and blood transfusions.

Generally, fifth disease is mild, and patients tend to improve without any complications. In cases where the patient is either immunocompromised or immunosuppressed, a life-threatening aplastic crisis can occur. With prompt treatment, however, the prognosis is good. Mothers who develop the infection while pregnant can pass the infection on to their fetus, and as such, stand an increased risk of miscarriage and stillbirth. There are tests and treatments, however, that can be performed on the fetus while still in the uterus that can reduce the risk of anemia or other complications.

Currently, there is no vaccine against fifth disease. Avoiding contact with persons who exhibit symptoms of a cold and maintaining good personal hygiene by regularly washing hands may minimize the chances of an infection. Pregnant women should avoid exposure to persons infected with the disease and notify their obstetrician immediately if they are exposed so that they can be tested and monitored closely.

Berktow, Robert, et al., editors. Merck Manual of Diagnosis and Therapy. Rahway, NJ: Merck Research Laboratories, 2004.

Anemia — A congenital or acquired deficiency in the iron-carrying capacity of the blood.

Antibody — A specific protein produced by the immune system in response to a specific foreign protein or particle called an antigen.

Immunocompromised — A state in which the immune system is weakened or is not functioning properly due to chronic disease.

Immunosuppressed — A state in which the immune system is suppressed by medications during the treatment of other disorders, like cancer, or following an organ transplantation.

Reye's syndrome — A very serious, rare disease, most common in children, that involves an upper respiratory tract infection followed by brain and liver damage.

Sickle cell anemia — A hereditary blood disorder in which the red blood cells are misshapen into crescent or sickle shapes resulting in the reduced oxygen-carrying capacity of the lungs.

erythema chro´nicum mi´grans a ring-shaped erythema due to the bite of a tick of the genus Ixodes; it begins as an erythematous plaque several weeks after the bite and spreads peripherally with central clearing. Often there are also systemic symptoms, including chills, fever, headache, vomiting, backache, and stiff neck. See also lyme disease.

gyrate erythema (erythema gyra´tum) erythema multiforme characterized by the development of lesions that tend to migrate and spread peripherally with central clearing.

erythema ab ig´ne permanent erythema produced by prolonged exposure to excessive nonburning heat. It is seen most often on the legs of women, but under appropriate environmental circumstances, it can occur anywhere on the body in either sex.

erythema indura´tum a chronic necrotizing vasculitis, usually occurring on the calves of young women; see also bazin's disease.

erythema infectio´sum a mild, self-limiting disease of childhood characterized by a lacelike skin rash symmetrically distributed on the hands, arms, and legs, with few or no other symptoms; occasionally there is a low grade fever, and the condition often clears up without specific treatment. The incubation period is six days to two weeks. This disease is contagious and originally was believed to be a form of rubella; because the rash can resemble that of scarlet fever and German measles, it is important to differentiate this mild condition from those more serious ones. Called also fifth disease.

erythema margina´tum a type of erythema multiforme in which the reddened areas are disk-shaped, with elevated edges.

erythema margina´tum rheuma´ticum a superficial, often asymptomatic, form of gyrate erythema associated with some cases of rheumatic fever, which is characterized by the presence on the trunk and extensor surfaces of the extremities of a transient eruption of flat to slightly indurated, nonscaling, and usually multiple lesions.

erythema mi´grans geographic tongue.

erythema multifor´me a symptom complex representing a reaction of the skin and mucous membranes secondary to various known, suspected, and unknown factors, including infections, ingestants, physical agents, malignancy, and pregnancy. The conditions in the complex are characterized by the sudden onset of a reddened macular, bullous, papular, or vesicular eruption, the characteristic lesion being the iris, bull's eye, or target lesion, which consists of a central papule with two or more concentric rings. The complex includes a mild self-limited mucocutaneous form (erythema multiforme minor) and a severe, sometimes fatal, multisystem form (stevens-johnson syndrome).

erythema nodo´sum a type of panniculitis occurring usually as a hypersensitivity reaction to multiple provoking agents, including various infections, drugs, sarcoidosis, and certain enteropathies. It may also be of idiopathic origin. It most often affects young women and is characterized by the development of crops of transient, inflammatory, nonulcerating nodules that are usually tender, multiple, and bilateral, and most commonly located on the shins; the lesions involute slowly, leaving bruiselike patches without scarring. The acute disease is often associated with fever, malaise, and arthralgias. A chronic variant sometimes occurs without any serious associated systemic disease.

toxic erythema (erythema tox´icum) a generalized erythematous or erythematomacular eruption due to administration of a drug or to bacterial or other toxins or associated with various systemic diseases.

erythema tox´icum neonato´rum a benign, idiopathic, very common, generalized, transient eruption occurring in infants during the first week of life, usually consisting of small papules or pustules that become sterile, yellow-white, firm vesicles surrounded by an erythematous halo and some edema.

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