Grantees of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, have adapted a rapid and accurate new molecular typing strategy and used it to conduct one of the most comprehensive studies of adenoviruses ever performed in the United States.
Adenoviruses commonly cause respiratory illnesses and infections of the stomach, intestine, eyes and bladder. Sometimes they cause epidemics and deaths. The new findings, from the extensive adenovirus epidemiological data collected in the United States, reveal that adenoviruses are frequently associated with hospitalizations and that some of these viruses may cause more severe disease than others.
The new gene sequencing strategy, first developed by researchers at the U.S. Centers for Disease Control and Prevention, identifies the adenovirus type in two days compared with the previous method that took weeks. The method¡¯s speed will help public health officials better understand adenovirus outbreaks in communities and other settings where people are in close contact, such as hospitals and long-term care facilities. It also will help clinicians know what type is causing the infection in order to use the appropriate antiviral treatment. Some adenovirus strains, particularly those considered as emerging pathogens, are more often associated with severe disease and death.
In an effort to better understand how adenovirus infection is caused and spread in different settings and populations, Gregory Gray, M.D., of the University of Iowa, and his colleagues analyzed clinical adenovirus-positive samples and patient data from 22 military and civilian medical facilities over a 25-month period. They characterized the strains of 2,237 adenovirus-positive specimens and compared their sequences with those of the 51 recognized strains that infect humans.
Highlights of their findings include the following:
- The distribution of adenovirus types varies by patient age, disease state, and geographical location.
- Adenovirus type 21 infections, which may cause more disease, have become more common.
- Fifty percent of the clinical adenovirus isolates among civilians were associated with hospitalization, about 20 percent with a chronic disease condition, 11 percent with bone marrow or solid organ transplantation, and 4 percent with a cancer diagnosis.
- Children under seven years of age, people with an underlying chronic disease, and those with recent organ transplantation are at greater risk of adenovirus infection and disease.
- A relatively high number of transplantation patients were found to have infections with multiple adenovirus isolates over time.
Researchers say quickly recognizing the adenovirus type is key to starting the appropriate antiviral therapy, controlling outbreaks and understanding the association of adenoviruses with a number of chronic disease conditions. Dr. Gray and his colleagues are using the molecular typing technique to help clinicians do just that.