Oct. 11, 2007
Researchers show clinical value of fingerprinting common respiratory viruses
Research conducted by University of Iowa investigators is providing valuable knowledge about adenoviruses, a family of viruses responsible for a number of human illnesses ranging from respiratory illness to gastroenteritis, conjunctivitis, cystitis, encephalitis and sometimes death. Their research involves use of a new molecular technique that reduces the time it takes to identify adenovirus types from weeks to two days.
Recent epidemiological and clinical data have revealed that such typing has great value in understanding adenovirus outbreaks that occur in communities, hospitals and especially in long-term care facilities, where new strains have proven deadly. For instance, in 1999 a new adenovirus strain caused illness in 84 percent of 50 long-term care facility residents, leading to 26 hospitalizations and seven deaths. Adenoviruses are also a major cause of severe illness among bone marrow transplant patients, where as many as 50 percent who are infected may die from adenovirus disease.
Typing is further valuable in that it shows clinicians how their patients are acquiring adenovirus infections and, as some adenovirus types respond better to specific therapies, also helps clinicians determine if a specific patient warrants antiviral therapy for his or her adenovirus infection.
"Before the National Institute of Allergy and Infectious Diseases funded this study, our best understanding of circulating adenovirus was from studies conducted in the 1970s, when molecular tools were not available," said Gregory Gray, M.D., the study's principal investigator and professor of epidemiology in the UI College of Public Health. "Modern molecular tools allow us to greatly reduce the time from virus detection to specific viral type identification, making molecular typing very valuable to epidemiologists and clinicians. Also, new strains of adenovirus have emerged, and these tools are helping us better understand why they are associated with more severe disease."
Employing new molecular typing techniques, researchers from the Center for Emerging Infectious Diseases, based in the UI College of Public Health, conducted a large epidemiologic study of human adenovirus infection in the United States.
During a 25-month period, they analyzed the strains of 2,237 adenovirus-positive specimens from 22 military and civilian medical facilities, and compared their gene sequences with those of the 51 currently recognized human adenovirus strains. Among their findings was an increasing trend over time in the detection of adenovirus type 21 in both civilians and military trainees and its association with more severe disease.
The results of their research appear in the Nov. 1 issue of the journal Clinical Infectious Diseases, now available online at http://www.journals.uchicago.edu/CID/journal/latest.html.
Speed is crucial when combating some adenovirus infections. Multiple outbreaks of adenoviral infection are presently occurring in the United States, resulting in significant morbidity and mortality among patients and medical staff.
"Rapidly establishing the type of virus causing an adenovirus infection is key to limiting the severity and scope of outbreaks, especially in patients with hospital-acquired infections and in immuno-compromised individuals," said Troy McCarthy, study coordinator at the UI Center for Emerging Infectious Diseases. "It isn't enough to know a person has an adenovirus infection. Physicians need to know what type is causing the infection in order to use the best antiviral treatment."
Gray and his colleagues are currently using the molecular typing technique to assist clinicians in evaluating and treating certain patients with adenovirus infection and to help public health officials investigate adenovirus infection epidemics.
"Almost every week we receive requests to help a hospital or laboratory with emergency adenovirus typing," Gray said.
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