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    RSV - Mild or menacing?

    Devan Lore’s first RSV infection made him cough. The second one sent him to the ICU. What accounted for the drastic difference?

    Devan Lore’s first bout with a common wintertime virus gave the toddler a weeklong runny nose and cough. While the illness was an added burden for the child, who was undergoing treatment for acute lymphoblastic leukemia, the virus soon cleared.

    At age 6, Devan again caught the respiratory syncytial (pronounced sin-SISH-ul) virus, or RSV. This time the results were terrifying.

    Within days, the virus moved deep into Devan’s lungs, causing pneumonia, necessitating a move to the Intensive Care Unit at St. Jude Children’s Research Hospital. The boy spent 12 hours a day in an oxygen tent, where he inhaled an antiviral drug.

    “From 8 p.m. to 8 a.m. for five days,” recalls Gail Lore, Devan’s mother. “I wanted to reach out, hold him, cuddle him—and couldn’t.”

    Following this regimen, Devan continued around-the-clock breathing treatments.

    “It was two weeks before he was well enough to be taken off oxygen, and he was still so weak afterwards,” Gail says. “It was easily our roughest patch at St. Jude.”

    Although usually associated with cold-like symptoms, RSV is the most common cause of bronchiolitis and pneumonia among children under 1 year of age. Repeated RSV infections can occur throughout life in otherwise healthy people. The virus can present severe problems in those who are extremely young, elderly or in people who have compromised cardiac, pulmonary or immune systems. For children with cancer, especially those who have had recent bone marrow transplants, the virus can be deadly.

    More than a cold

    Devan’s two brushes with the virus typified how RSV infection can develop in completely different ways. In both instances, Devan’s immune system was weakened from chemotherapy, but his first round with the virus produced cold-like symptoms, while the second threatened his life.

    To better understand the difference in response, investigators reviewed the cases of St. Jude patients who had experienced RSV infections. The researchers sought a common thread that would help them identify which children were at greatest risk.

    “Before our study, most information about RSV infection in patients with cancer came from adult patients—information that was not necessarily applicable to the children we treat,” says Aditya Gaur, MD, of St. Jude Infectious Diseases. “We needed data from children and adolescents with cancer to be able to put together RSV management guidelines. We wanted to know if there were characteristics that would tell us up front which patients might have a particularly severe course of RSV infection.”

    Lymphocytes are key

    The research team studied the St. Jude records of 58 children with cancer who had tested positive for RSV between 1998 and 2005.

    The investigators found that children under 2 years old and those with low levels of lymphocytes—infection-fighting white blood cells—are at high risk for more severe RSV-related disease.

    “The new information is important because it helps identify children with cancer who are most at risk for severe disease by using easily available clinical information,” Gaur says. “The findings don’t imply that all patients with one or both risk factors will develop a serious RSV infection, but they tell us who needs to be considered for antiviral therapy, which is costly and often inconvenient to receive from a child’s perspective.”

    Investigators also found that they could predict risk more accurately by evaluating a child’s lymphocyte count instead of the neutrophil count. Neutrophils are immune system cells that engulf and digest germs.

    “With cancer patients, clinicians are used to identifying those at risk for infections based on patients having abnormally low levels of neutrophils,” Gaur says. “But our study shows that for RSV, low levels of lymphocytes and not neutrophils identify those at risk for severe disease.” Total neutrophil count and total lymphocyte count are both available as part of routine blood tests for patients with cancer.

    Asking the right questions

    The project began three years ago, when Gaur and former St. Jude fellow C. M. El Saleeby, MD, treated two children who had life-threatening RSV infections.

    “When you have someone who is very sick, you try your best to find the answer that will help and to ask yourself whether the severity of sickness could have been predicted,” Gaur recalls. “There was information about adults, but the information wasn’t there for the children we were trying to treat.”

    El Saleeby and Gaur started to ask questions that were not being posed about pediatric patients; in so doing, they found new answers that promise to improve care for these children.

    “While the RSV management guideline that has been developed based on our study’s findings is a good first step toward optimizing treatment of this infection, further research is necessary,” Gaur says. “Ultimately, good, consistent hand hygiene at home and in the hospital is the most cost-effective way of preventing not only RSV but many other viral infections.”

    All of these findings by Gaur and his colleagues are sure to make kids—as well as moms like Gail Lore—breathe much more easily.

    Editor's Note: Devan Lore passed away September 2010.

    Reprinted from Promise, Summer 2008

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