Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SATURDAY, July 28, 1990 TAG: 9007280330
SECTION: EXTRA PAGE: 3 EDITION: METRO
SOURCE: Jane E. Brody
DATELINE: LENGTH: Long
A little-known virus that causes mini-epidemics among elementary schoolchildren in April, May and June also takes a break.
The virus, known as parvovirus B19, usually causes a mild, flu-like illness called fifth disease, well known to physicians who treat children.
But hardly anyone has ever heard of it, either by its common name or its scientific name, erythema infectiosum. Yet, 60 percent of Americans are infected by it at some time in their childhood, usually from the ages of 5 to 9.
Fifth disease is an old illness, but until recently it was all but ignored in medical circles.
Then, in the 1980's, parvovirus B19 was linked to sometimes fatal problems in certain people, including unborn children, people with incurable anemia and patients with deficient immune systems.
The common name of the disease reflects its history. According to Dr. Michael Ryan, director of pediatric specialties at Geisinger Medical Center in Danville, Pa., around the turn of the century physicians gave numerical names to common diseases that caused fever and rash.
Measles was first disease, scarlet fever was second disease, rubella was third disease, a nondisease called Duke's disease was fourth disease, and roseola was sixth disease.
But only for erythema infectiosum did the numerical appellation of fifth disease stick.
The virus now known to cause fifth disease was not discovered until 1975. It was picked up accidentally in two healthy blood donors who were being screened for hepatitis B virus.
It was not until 1983 that the virus was shown to be the cause of erythema infectiosum.
Rarely is there any cause for concern about parvovirus infections in children. Many never even realize they are sick, just a little out of sorts for a few days, sometimes with a slight fever.
In fact, many infected children continue to go to school, where they spread the virus by airborne droplets to others not yet immune.
The most telling sign of fifth disease is a rash on the cheeks and sometimes the arms that resembles the red mark left by a slap.
But by the time the rash appears, the contagious period is long gone and the child feels well.
The main trouble with parvovirus is that it manages to miss infecting 40 percent of children before they become adults. When otherwise healthy adults acquire the infection, their symptoms tend to be more serious.
Arthritic-like pain in the joints is common and sometimes persists for weeks or months. Until tests prove otherwise, the ailment can be mistaken for arthritis or Lyme disease.
But the most serious problem with parvovirus involves people with immune deficiences, those with acquired anemia or hereditary anemia like sickle cell disease, and pregnant women who never had the disease as children.
In 1981 researchers discovered that people with serious anemia can develop profound, life-threatening anemia from a parvovirus infection.
The virus attacks the bone marrow cells where new red blood cells are produced. Since red blood cells are the ones that carry oxygen to body tissues, the heart must work overtime to deliver needed oxygen, and congestive heart failure, sometimes fatal, can result.
A similar crisis can occur when the virus infects people with compromised immune systems. Such immune deficiencies may be caused by diseases like AIDS or by immunosuppressive medical treatments like chemotherapy for cancer.
Not until 1984 was parvovirus B19 linked to miscarriage and stillbirth. Pregnant women who had escaped the infection in childhood can become infected by the virus and may not even be aware of their infection.
In a small percentage of cases the virus attacks their unborn babies, causing a shutdown of red blood cell production in the fetal bone marrow. It can cause problems in the child later in life or even result in a stillbirth or miscarriage.
The fetal heart goes into congestive failure, the fetal tissues become severely swollen (a condition called hydrops fetalis) and the fetus dies. A miscarriage or stillbirth is the result.
What can a woman do to protect herself and her unborn child from possible harm by parvovirus? First, she has little reason for concern unless the disease is occurring in her community and she is likely to be exposed to young children.
Again, the most likely time for such an outbreak is in the spring. Schoolteachers, school cafeteria workers and day care workers are at greatest risk, along with women who are mothers of school-age children.
A woman can find out if she is susceptible to fifth disease through a blood test that checks for antibodies to the virus. The tests can tell if she has recently been infected, if she was infected long ago or if she has never had the disease and is therefore still susceptible to infection.
Ryan said that only two laboratories now do the test: the Centers for Disease Control in Atlanta and the Microbiology References Laboratory in Cypress, Calif. Physicians can send blood samples for analysis.
by CNB