Fifth disease



Definition

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.

Description

The Latin name for fifth 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. Some individuals exhibit no symptoms and never even feel ill.

Transmission

The virus that causes fifth disease lives in the nose, mouth, and throat of an infected person; therefore, the virus can be spread through the air by coughing and sneezing. It can also be spread through shared drinking glasses and eating utensils.

Demographics

Fifth disease is very common in children between the ages of five and 15. Studies show that although 40 percent to 60 percent of adults worldwide have laboratory evidence of a past parvovirus B19 infection, most of these adults cannot remember having had symptoms of fifth disease. This fact leads medical experts to believe that most people with parvovirus B19 infection have either very mild symptoms or no symptoms at all.

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

In households where a child has fifth disease, another family member who has not previously had fifth disease has about a 50 percent chance of also getting the infection, while classmates of a child with fifth disease have about a 60 percent chance of getting the disease.

Causes and symptoms

Fifth disease is caused by the human parvovirus B19, a member of the Parvoviridae family of viruses, that lives in the nose, mouth, and throat of an infected person. 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 28 days after being exposed to the virus, with the average time to onset ranging from 16 to 17 days. Initial symptoms are flu-like and include headache , stuffy or runny nose, 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. Other symptoms that sometimes occur with fifth disease include swollen glands, red eyes, and diarrhea . In older teens and adults, fifth disease may be followed by joint swelling or pain in the hands, wrists, knees, and ankles, lasting from a few months to several years.

In children, especially those under the age of ten, a bright red rash that looks like a slap mark develops suddenly on the cheeks a few days after the original symptoms were experienced. 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 as the centers of the blotches fade. By the time the rash appears, individuals are no longer infectious. On average, the rash lasts for ten to 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 .

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 children, the anemia is mild and only lasts a short while. In children 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 in which 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

Infant with a rash caused by fifth disease, or erythema infectiosum. (Custom Medical Stock Photo, Inc.)
Infant with a rash caused by fifth disease, or erythema infectiosum.
(Custom Medical Stock Photo, Inc.)
also aggravate symptoms for people with an autoimmune disease called systemic lupus erythematosus.

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 due to the fetus developing severe anemia. There is also some concern that infection later in pregnancy may involve a very small risk of premature delivery or stillbirth. As a result, women who get fifth disease while they are pregnant should be monitored closely by a physician.

When to call the doctor

Parents should call their child's doctor if their child develops a rash, especially if the rash is widespread over the child's body or if the rash is accompanied by other symptoms.

KEY TERMS

Anemia —A condition in which there is an abnormally low number of red blood cells in the bloodstream. It may be due to loss of blood, an increase in red blood cell destruction, or a decrease in red blood cell production. Major symptoms are paleness, shortness of breath, unusually fast or strong heart beats, and tiredness.

Antibody —A special protein made by the body's immune system as a defense against foreign material (bacteria, viruses, etc.) that enters the body. It is uniquely designed to attack and neutralize the specific antigen that triggered the immune response.

Immunocompromised —A state in which the immune system is suppressed or not functioning properly.

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 serious, life-threatening illness in children, usually developing after a bout of flu or chickenpox, and often associated with the use of aspirin. Symptoms include uncontrollable vomiting, often with lethargy, memory loss, disorientation, or delirium. Swelling of the brain may cause seizures, coma, and in severe cases, death.

Sickle cell anemia —An inherited disorder in which red blood cells contain an abnormal form of hemoglobin, a protein that carries oxygen. The abnormal form of hemoglobin causes the red cells to become sickle-shaped. The misshapen cells may clog blood vessels, preventing oxygen from reaching tissues and leading to pain, blood clots and other problems.

Diagnosis

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 such as 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 percent specific for this disease.

Because fifth disease can pose problems for an unborn fetus exposed to the disease through the mother, testing for the disease may 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.

Prognosis

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 thus 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.

Prevention

As of 2004, there was 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 obstetricians immediately if they are exposed so that they can be tested and monitored closely.

Parental concerns

Generally parents should not be concerned if their child contracts fifth disease. However, if the mother is pregnant, she should contact her doctor.

Resources

BOOKS

Laskey, Elizabeth. Fifth Disease. It's Catching Series. Oxford, UK: Heinemann Library, 2003.

PM Medical Health News. 21st Century Complete Medical Guide to Fifth Disease, Parvovirus: Authoritative Government Documents, Clinical References, and Practical Information for Patients and Physicians. Washington, DC: Progressive Management, 2004.

WEB SITES

Eppes, Stephen. "Fifth Disease." KidsHealth , April 2004. Available online at http://kidshealth.org/parent/infections/bacterial_viral/fifth.html/ (accessed November 18, 2004).

"Fifth Disease." Centers for Disease Control (CDC) , September 7, 2004. Available online at http://www.cdc.gov/ncidod/diseases/parvovirus/B19.htm (accessed November 18, 2004).

Judith Sims, MS Lata Cherath, PhD



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