Measles outbreak in a pediatric practice: airborne transmission in an office setting.

In February 1981, a measles outbreak occurred in a pediatric practice in DeKalb County, GA. The source case, a 12-year-old boy vaccinated against measles at 11 1/2 months of age, was in the office for one hour on the second day of rash, primarily in a single examining room. On examination, he was noted to be coughing vigorously. Seven secondary cases of measles occurred due to exposure in the office. Four children had transient contact with the source patient as he entered or exited through the waiting room; only one of the four had face-to-face contact within 1 m of the source patient. The three other children who contracted measles were never in the same room with the source patient; one of the three arrived at the office one hour after the source patient had left. The risk of measles for unvaccinated infants (attack rate 80%, 4/5) was 10.8 times the risk for vaccinated children (attack rate 7%, 2/27) (P = .022, Fisher exact test, two-tailed). Airflow studies demonstrated that droplet nuclei generated in the examining room used by the source patient were dispersed throughout the entire office suite. Airborne spread of measles from a vigorously coughing child was the most likely mode of transmission. The outbreak supports the fact that measles virus when it becomes airborne can survive at least one hour. The rarity of reports of similar outbreaks suggests that airborne spread is unusual. Modern office design with tight insulation and a substantial proportion of recirculated ventilation may predispose to airborne transmission.

Potable water as a source of Legionnaires' disease.

A three-year epidemic of legionnaires' disease in a hospital was dramatically curtailed following hyperchlorination of the potable water supply. The hypothesis that potable water was the source for the outbreak was further supported by isolation of Legionella pneumophila (the agent of legionnaires' disease) from the hospital water supply, observation that a sudden upsurge had occurred in the number of cases following a peculiar manipulation of the hospital water system, and documentation of a 30-fold increase in concentration of organisms in the water when this manipulation was artificially recreated. Thus, potable water may be an important source of epidemic legionnaires' disease and continuous hyperchlorination a method of control.

Ventilation and air conditioning--a primer for nonengineers.

Some aspects of ventilation and air conditioning have been explained for infection control personnel who are not engineers. With more understanding of ventilation, infection control personnel may be able to communicate better with engineering personnel on this subject.

Improved system for floor cleaning in health care facilities.

A new system has been developed for sanitizing floors in hospitals; this system replaces the traditional procedure of daily dusting and wet mopping with a disinfectant-detergent solution and periodic buffing . This new system relies on a sequence of procedures consisting of dust mopping using a chemically treated dust mop, machine buffing of a sprayed-on polymer treatment, and a second dust mopping . The effectiveness of the procedures was evaluated by means of surface sampling for bacterial contamination and air sampling for airborne bacteria and dust. The level of bacterial contamination on the floors was reduced by 93.6% by using the new system, compared with 79.8% by using the conventional process of dust mopping and wet mopping with a disinfectant solution. The levels of airborne bacteria during and after the individual procedures did not vary significantly from the initial level (123.6 CFU/per m3 of air). A survey of representative colonies from air samples revealed staphylococci, gram-positive bacilli, gram-positive diplococci, yeast cells, and infrequent gram-negative rods. The distribution at the conclusion of the sanitizing process was similar to that at the outset. Similarly, the levels of airborne dust measured during and after the individual procedures did not vary significantly from the initial level. When compared with the traditional method of cleaning by wet mopping , the new method was significantly more effective in removal of microbial contamination and required less labor.

Carpeting in hospitals: an epidemiological evaluation.

Epidemiological and microbiological studies were conducted in a hospital room with carpet (CR) and in one with carpet (NCR). Microbiological profiles were determined with specimens obtained from patients admitted to these rooms. Patient records were reviewed to note infection status and other case identities. Eleven-millimeter cylindrical core samples of carpet were obtained, and swab template techniques were used on the bare floor for subsequent enumeration and identification of contaminating microorganisms. In each sampling period, higher microbial counts per square inch (1 in(2) = ca 6.452 cm(2)) were measured for the carpet than for the bare floor. Recovery rates of Enterobacter spp., Klebsiella pneumoniae, and Escherichia coli were higher from carpet samples than from bare floor samples. Typable organisms (such as E. coli, Pseudomonas aeruginosa, K. pneumoniae, and Staphylococcus aureus) obtained from patients were also more frequently recovered from the carpet than from the bare flooring. Patients who stayed in the CR were shown to be colonized with the same types of organisms as those initially recovered from the carpet. However, no statistically significant differences were found in patients in the CR versus NCR in colonization with all typable and nontypable organisms first found on the floor. Disease in patients was found not to be associated with organisms found as contaminants of the carpet or the bare floor. Air above carpeting contained more consistent concentrations of organisms than air above the bare flooring.

Failure of Legionella pneumophila sensitivities to predict culture results from disinfectant-treated air-conditioning cooling towers.

The disinfection of cooling towers based on manufacturers' treatment protocols, as employed in units installed at various public gathering places in Dallas, Tex. (hotels, municipal auditorium), and at the city health department, was evaluated for effectiveness in controlling Legionella pneumophila and compared with previous laboratory studies. In specimens collected in September and December, 1978, L. pneumophila was isolated from 2 of 4 specimens from untreated cooling towers, 2 of 4 specimens from towers treated with agents deemed ineffective in earlier laboratory tests, 6 of 11 specimens from towers treated with putatively effective agents, and 0 of 4 specimens from towers treated with an agent unknown efficacy. These results suggest the need for further studies to identify biocidal agents effective in eliminating L. pneumophila from air-conditioning cooling towers.

Epidemic Legionnaires' disease. Airborne transmission down a chimney.

Between June 18 and July 9, 1979, Legionnaires' disease (LD) developed in 13 persons who had visited a hotel complex in Wisconsin. All had visited the part of the hotel that contains the restaurants and meeting rooms (building A). Legionnaires' disease occurred in 1% who had been exclusively in the meeting rooms and in 0.1% who had eaten only at the hotel restaurants. Furthermore, 1.5% exposed to meeting room 1 and none of those exposed only to the other meeting rooms had LD. Legionella pneumophila was isolated from water in the cooling tower on top of building A. Located within 5 m downwind of the cooling-tower exhaust, a chimney with an open damper allowed cooling-tower exhaust (as demonstrated by air tracer studies) to enter meeting room 1 via the fireplace. Although cases did not occur after the cooling-tower water was treated by continuous hyperchlorination and the chimney was sealed, a seven-day lag occurred between treatment and elimination of the organism from the tower water.

Microbiologic sampling of the inanimate environment in U.S. hospitals, 1976-1977.

Data obtained in the first two phases of the Study on the Efficacy of Nosocomial Infection Control (SENIC Project) indicate that in 1975 three-quarters of U.S. hospitals performed environmental culturing on a routine basis; however, between 1970 and 1975, one-quarter had reduced the extent of environmental culturing permanently. Large hospitals (greater than or equal to 200 beds) and those with an infection control nurse who had completed a training course in hospital epidemiology were more likely to have reduced the extent of culturing. In 1976-1977 hospitals that performed such culturing collected an average of 500 environmental cultures per year, whereas larger hospitals and those with an infection control nurse collected significantly fewer cultures. Only 28 percent of the approximately two million environmental cultures collected in U.S. hospitals in 1975 were indicated by recommendations of the Centers for Disease Control and the American Hospital Association current at the time.

Recommendations for reducing risks of infection associated with suction collection procedures.

It is recognized that risks are incurred when health care workers contact various body fluids. The handling of suction collection equipment poses a risk because it is one way workers may come in contact with these fluids. Minimizing the risks associated with suction procedures can be accomplished if appropriate policies and procedures can be developed in health care facilities.

Legionnaires' disease outbreak at an Atlanta, Georgia, Country Club: evidence for spread from an evaporative condenser.

During July 1978 an outbreak of Legionnaires' disease characterized by high fever, prostration, and pneumonia occurred at an Atlanta, Georgia, country club. All eight cases involved club members whose primary club activity was golfing. The degree of golfing activity during the likely exposure period was a risk factor for acquiring the illness. Legionella pneumophila was isolated from the evaporative condenser within the clubhouse. The fact that the stream of air blowing from the exhaust duct of the evaporative condenser was directed toward a nearby practice green and the 10th and 16th tees supports the hypothesis that this outbreak represents airborne dissemination of L. pneumophila from the evaporative condenser to an outdoor site where susceptible golfers contracted the illness.

An outbreak of Legionnaires' disease associated with a contaminated air-conditioning cooling tower.

In August and September 1978, an outbreak of Legionnaires' disease occurred in Memphis, Tennessee. Of the 44 ill, 39 had been either patients, employees, visitors, or passers-by at one Memphis hospital (Hospital A) during the 10 days before. Assuming an incubation period of between two and 10 days, the onset of cases correlated precisely with the use of Hospital A's auxiliary air-conditioning cooling tower. L. pneumophila was recovered from two samples of water from the tower. Infection appeared to have occurred both outside and within the hospital. A significant association was demonstrated between acquisition of Legionnaires' disease and prior hospitalization in those areas of Hospital A that received ventilating air from air intakes near the auxiliary cooling tower. Tracer-smoke studies indicated that contaminated aerosols from the tower could easily reach these air intakes, as well as the street below, where four passers-by had been before they contracted Legionnaires' disease. This represents a common-source outbreak in which the source of L. pneumophila infection and airborne transmission were identified.