LOW OUTDOOR AIR SUPPLY IN BUILDINGS INCREASES EXPOSURE RISK TO COLD VIRUSES
In contrast to prior studies showing that hand contact transmitted cold viruses, investigators who sampled air from 3 buildings over 20 months found that occupants in buildings with a low outdoor air supply appeared to be at increased exposure risk to infectious cold droplets from fellow workers through the building's ventilation system. Researchers sampled air in 3 different office buildings from 9 a.m. to 5 p.m. each work day, detecting airborne viruses in 32 percent of air sampling filters in the offices, using molecular methods. The investigators said that their data demonstrated a significant positive relationship between frequency of virus detection in air filters and degree of building ventilation. Outdoor air levels were measured by carbon dioxide concentrations greater than 100 parts per million above the background level. Consequently, the data suggested that lower ventilation rates and resulting higher carbon dioxide concentrations are associated with an increased risk of exposure to potentially infectious droplet nuclei from persons with colds. In addition to the positive relationship associated with building ventilation and outside air, the researchers discovered that one rhinovirus from a nasal lavage taken from a volunteer with a cold contained an identical nucleic acid sequence similar to that in the building air sample collected during the week. According to the researchers, cold viral respiratory infections are the most common infectious disease in the U.S., are associated with an annual cost of $25 billion in direct and indirect costs, cause excessive and inappropriate antibiotic prescribing, and lead to 20 million days of work loss each year. The study appears in the first issue for June 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
PHYSICIANS AND NURSES TREATING SARS PATIENTS ARE AT HIGH RISK OF DEVELOPING THE DISEASE
Physicians and nurses who become involved in the early critical care phase of treatment directed at patients with severe acute respiratory syndrome (SARS), along with health care workers who performed endotracheal intubation on these patients, were at substantially increased risk of contracting the illness, according to Canadian clinical investigators. The researchers studied 122 critical care staff that were at risk during the outbreak period, April 1 through 22, 2003. The group included 66 nurses, 18 nursing aids/patient assistants, 15 physicians, 18 respiratory therapists, and 2 other health care workers. All 122 members of the staff had exposure to 7 SARS patients. Ten critical care workers (5 critical care nurses, 2 respiratory therapists, and 3 physicians) were later diagnosed with the disease. The researchers pointed out that physicians performing endotracheal intubation had a 3.8-fold greater likelihood of subsequently developing SARS than did physicians caring for patients with SARS who did not perform the procedure. (Endotracheal tubes are catheters inserted through the mouth or nose into the trachea to maintain an open airway and to deliver oxygen.) According to the authors, all healthcare workers with SARS were subsequently hospitalized. They said that most received supplemental oxygen and antimicrobial therapy, but that none became critically ill. In an editorial in the same issue Stéphane Hugonnet, M.D., M.Sc., and Didier Pittet, M.D., M.S., of the Infection Control Program, University of Geneva Hospital, Geneva, Switzerland, noted that, in SARS transmission to healthcare workers, adequate use of standard personal protective equipment appeared to be the cornerstone of the problem. Unfortunately, they said, more precise data on the use of the personal protective equipment was not provided by the authors of this study. The research and editorial appear in the first issue for June 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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